AT91SAM9G20_1

Features • Incorporates the ARM926EJ-S™ ARM® Thumb® Processor – DSP Instruction Extensions, ARM Jazelle® Technology for Java® Acceleration – 32-KByte Data Cache, 32-KByte Instruction Cache, Write Buffer – CPU Frequency 400 MHz – Memory Management Unit – EmbeddedICE™, Debug Communication Channel Support Additional Embedded Memories – One 64-KByte Internal ROM, Single-cycle Access at Maximum Matrix Speed – Two 16-KByte Internal SRAM, Single-cycle Access at Maximum Matrix Speed External Bus Interface (EBI) – Supports SDRAM, Static Memory, ECC-enabled SLC NAND Flash and CompactFlash® USB 2.0 Full Speed (12 Mbits per second) Device Port – On-chip Transceiver, 2,432-byte Configurable Integrated DPRAM USB 2.0 Full Speed (12 Mbits per second) Host and Dual Port – Single or Dual On-chip Transceivers – Integrated FIFOs and Dedicated DMA Channels Ethernet MAC 10/100 Base T – Media Independent Interface or Reduced Media Independent Interface – 128-byte FIFOs and Dedicated DMA Channels for Receive and Transmit Image Sensor Interface – ITU-R BT. 601/656 External Interface, Programmable Frame Capture Rate – 12-bit Data Interface for Support of High Sensibility Sensors – SAV and EAV Synchronization, Preview Path with Scaler, YCbCr Format Bus Matrix – Six 32-bit-layer Matrix – Boot Mode Select Option, Remap Command Fully-featured System Controller, including – Reset Controller, Shutdown Controller – Four 32-bit Battery Backup Registers for a Total of 16 Bytes – Clock Generator and Power Management Controller – Advanced Interrupt Controller and Debug Unit – Periodic Interval Timer, Watchdog Timer and Real-time Timer Reset Controller (RSTC) – Based on a Power-on Reset Cell, Reset Source Identification and Reset Output Control Clock Generator (CKGR) – Selectable 32,768 Hz Low-power Oscillator or Internal Low Power RC Oscillator on Battery Backup Power Supply, Providing a Permanent Slow Clock – 3 to 20 MHz On-chip Oscillator, One up to 800 MHz PLL and One up to 100 MHz PLL Power Management Controller (PMC) – Very Slow Clock Operating Mode, Software Programmable Power Optimization Capabilities – Two Programmable External Clock Signals Advanced Interrupt Controller (AIC) – Individually Maskable, Eight-level Priority, Vectored Interrupt Sources – Three External Interrupt Sources and One Fast Interrupt Source, Spurious Interrupt Protected Debug Unit (DBGU) – 2-wire UART and Support for Debug Communication Channel, Programmable ICE Access Prevention • • • • AT91 ARM Thumb Microcontrollers AT91SAM9G20 Preliminary • • • • • • • • • 6384D–ATARM–04-May-09 – Mode for General Purpose 2-wire UART Serial Communication • Periodic Interval Timer (PIT) – 20-bit Interval Timer plus 12-bit Interval Counter • Watchdog Timer (WDT) – Key-protected, Programmable Only Once, Windowed 16-bit Counter Running at Slow Clock • Real-time Timer (RTT) – 32-bit Free-running Backup Counter Running at Slow Clock with 16-bit Prescaler • One 4-channel 10-bit Analog-to-Digital Converter • Three 32-bit Parallel Input/Output Controllers (PIOA, PIOB, PIOC) – 96 Programmable I/O Lines Multiplexed with up to Two Peripheral I/Os – Input Change Interrupt Capability on Each I/O Line – Individually Programmable Open-drain, Pull-up Resistor and Synchronous Output – All I/O Lines are Schmitt Trigger Inputs Peripheral DMA Controller Channels (PDC) One Two-slot MultiMedia Card Interface (MCI) – SDCard/SDIO and MultiMediaCard™ Compliant – Automatic Protocol Control and Fast Automatic Data Transfers with PDC One Synchronous Serial Controller (SSC) – Independent Clock and Frame Sync Signals for Each Receiver and Transmitter – I²S Analog Interface Support, Time Division Multiplex Support – High-speed Continuous Data Stream Capabilities with 32-bit Data Transfer Four Universal Synchronous/Asynchronous Receiver Transmitters (USART) – Individual Baud Rate Generator, IrDA® Infrared Modulation/Demodulation, Manchester Encoding/Decoding – Support for ISO7816 T0/T1 Smart Card, Hardware Handshaking, RS485 Support – Full Modem Signal Control on USART0 Two 2-wire UARTs Two Master/Slave Serial Peripheral Interfaces (SPI) – 8- to 16-bit Programmable Data Length, Four External Peripheral Chip Selects – Synchronous Communications Two Three-channel 16-bit Timer/Counters (TC) – Three External Clock Inputs, Two Multi-purpose I/O Pins per Channel – Double PWM Generation, Capture/Waveform Mode, Up/Down Capability – High-Drive Capability on Outputs TIOA0, TIOA1, TIOA2 One Two-wire Interface (TWI) – Compatible with Standard Two-wire Serial Memories – One, Two or Three Bytes for Slave Address – Sequential Read/Write Operations – Master, Multi-master and Slave Mode Operation – Bit Rate: Up to 400 Kbits – General Call Supported in Slave Mode – Connection to Peripheral DMA Controller (PDC) Channel Capabilities Optimizes Data Transfers in Master Mode IEEE® 1149.1 JTAG Boundary Scan on All Digital Pins Required Power Supplies – 0.9V to 1.1V for VDDBU, VDDCORE, VDDPLL – 1.65 to 3.6V for VDDOSC – 1.65V to 3.6V for VDDIOP (Peripheral I/Os) – 3.0V to 3.6V for VDDUSB – 3.0V to 3.6V VDDANA (Analog-to-digital Converter) – Programmable 1.65V to 1.95V or 3.0V to 3.6V for VDDIOM (Memory I/Os) Available in a 217-ball LFBGA and 247-ball TFBGA RoHS-compliant Package • • • • • • • • • • • 2 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 1. Description The AT91SAM9G20 is based on the integration of an ARM926EJ-S processor with fast ROM and RAM memories and a wide range of peripherals. The AT91SAM9G20 embeds an Ethernet MAC, one USB Device Port, and a USB Host controller. It also integrates several standard peripherals, such as the USART, SPI, TWI, Timer Counters, Synchronous Serial Controller, ADC and MultiMedia Card Interface. The AT91SAM9G20 is architectured on a 6-layer matrix, allowing a maximum internal bandwidth of six 32-bit buses. It also features an External Bus Interface capable of interfacing with a wide range of memory devices. The AT91SAM9G20 is an enhancement of the AT91SAM9260 with the same peripheral features. It is pin-to-pin compatible with the exception of power supply pins. Speed is increased to reach 400 MHz on the ARM core and 133 MHz on the system bus and EBI. 3 6384D–ATARM–04-May-09 Figure 2-1. MASTER L S TD TDI TMO TC S RTK CK JT AG SE ET EX T CK EX C EN ER ERRS -E XC T ERXE -EC XE K ROR EX T 0- -ER L M X0 ER XD D- X M C ETX 3 V D 3 F1 IO 00 TST Transc. Transc. In-Circuit Emulator System Controller JTAG Selection and Boundary Scan FIQ IRQ0-IRQ2 AIC DBGU ICache 32K bytes MMU Bus Interface DCache 32K bytes ARM926EJ-S Processor USB OHCI FIFO DMA DMA DMA D FIFO BM 10/100 Ethernet MAC DRXD DTXD PCK0-PCK1 I PDC PMC PLLA AT91SAM9G20 Block Diagram Filter Filter PLLB 2. AT91SAM9G20 Block Diagram XIN XOUT OSC WDT PIT 6-layer Matrix RC 4GPREG G TW CTD T WC K RS T 0SC S0 CT S RX K0 -RT 3 -S TXD0- SCK3 D0 RX 2 -T D5 X DS D5 DCR0 D0 R DT I0 R0 M CD B0 -M CD M CD MC B3 CD A 0MB C M DA C CD 3 MA CC K NP NC PS NPCS3 NPCS2 C1 SP S0 M CK O T M SI CL IS O TI K0 O -T TI A0- CL O TK TC B0 IO 2 L -T A2 TI K3 IOB OTI A3 TC 2 L O B3-TIOK5 -T A IO 5 B5 TK TF TD RD RF RK AD 0AD AD 3 TR IG AD VR EF V DD AN A ND AN A 6384D–ATARM–04-May-09 SPI0_, SPI1_ DD DDM P AT91SAM9G20 Preliminary PIOA PIOB PIOC Peripheral Bridge 24-channel Peripheral DMA ROM 64 Kbytes Fast SRAM 16 Kbytes Fast SRAM 16 Kbytes APB SDRAM Controller PDC PDC SPI0 SPI1 TC0 TC1 TC2 TC3 TC4 TC5 SSC PDC PDC TWI PDC DPRAM OSCSEL XIN32 XOUT32 OSC RTT SHDN WKUP VDDBU SHDC POR VDDCORE POR RSTC NRST PDC MCI 4-channel 10-bit ADC USART0 USART1 USART2 USART3 USART4 USART5 IS I_ M IS CK I_ IS PC I_ K IS DO I_ -I V IS S SI I_ YN _D7 HS C YN C H D HD PA M A Image Sensor Interface EBI CompactFlash NAND Flash USB Device Static Memory Controller ECC Controller Transceiver HD P HD B M B 4 D0-D15 A0/NBS0 A1/NBS2/NWR2 A2-A15, A18-A20 A16/BA0 A17/BA1 NCS0 NCS1/SDCS NRD/CFOE NWR0/NWE/CFWE NWR1/NBS1/CFIOR NWR3/NBS3/CFIOW SDCK, SDCKE RAS, CAS SDWE, SDA10 NANDOE, NANDWE A21/NANDALE, A22/NANDCLE D16-D31 NWAIT A23-A24 NCS4/CFCS0 NCS5/CFCS1 A25/CFRNW CFCE1-CFCE2 NCS2, NCS6, NCS7 NCS3/NANDCS SLAVE AT91SAM9G20 Preliminary 3. Signal Description Table 3-1. Signal Name Signal Description List (Continued) Function Power Supplies Type Active Level Comments VDDIOM VDDIOP VDDBU VDDANA VDDPLL VDDOSC VDDCORE VDDUSB GND GNDANA GNDBU GNDUSB GNDPLL EBI I/O Lines Power Supply Peripherals I/O Lines Power Supply Backup I/O Lines Power Supply Analog Power Supply PLL Power Supply Oscillator Power Supply Core Chip Power Supply USB Power Supply Ground Analog Ground Backup Ground USB Ground PLL Ground Power Power Power Power Power Power Power Power Ground Ground Ground Ground Ground 1.65V to 1.95V or 3.0V to 3.6V 1.65V to 3.6V 0.9V to 1.1V 3.0V to 3.6V 0.9V to 1.1V 1.65V to 3.6V 0.9V to 1.1V 1.65V to 3.6V Clocks, Oscillators and PLLs XIN XOUT XIN32 XOUT32 OSCSEL PCK0 - PCK1 Main Oscillator Input Main Oscillator Output Slow Clock Oscillator Input Slow Clock Oscillator Output Slow Clock Oscillator Selection Programmable Clock Output Input Output Input Output Input Output Accepts between 0V and VDDBU. Shutdown, Wakeup Logic SHDN WKUP Shutdown Control Wake-up Input ICE and JTAG NTRST TCK TDI TDO TMS JTAGSEL RTCK Test Reset Signal Test Clock Test Data In Test Data Out Test Mode Select JTAG Selection Return Test Clock Input Input Input Output Input Input Output No pull-up resistor Pull-down resistor. Accepts between 0V and VDDBU. Low Pull-up resistor No pull-up resistor No pull-up resistor Output Input Accepts between 0V and VDDBU. 5 6384D–ATARM–04-May-09 Table 3-1. Signal Name Signal Description List (Continued) Function Reset/Test Type Active Level Comments NRST TST Microcontroller Reset Test Mode Select I/O Input Low Pull-up resistor Pull-down resistor. Accepts between 0V and VDDBU. No pull-up resistor BMS = 0 when tied to GND. BMS = 1 when tied to VDDIOP. BMS Boot Mode Select Debug Unit - DBGU Input DRXD DTXD Debug Receive Data Debug Transmit Data Input Output Advanced Interrupt Controller - AIC IRQ0 - IRQ2 FIQ External Interrupt Inputs Fast Interrupt Input Input Input PIO Controller - PIOA - PIOB - PIOC PA0 - PA31 PB0 - PB31 PC0 - PC31 Parallel IO Controller A Parallel IO Controller B Parallel IO Controller C I/O I/O I/O Pulled-up input at reset Pulled-up input at reset Pulled-up input at reset External Bus Interface - EBI D0 - D31 A0 - A25 NWAIT Data Bus Address Bus External Wait Signal I/O Output Input Low Pulled-up input at reset 0 at reset Static Memory Controller - SMC NCS0 - NCS7 NWR0 - NWR3 NRD NWE NBS0 - NBS3 Chip Select Lines Write Signal Read Signal Write Enable Byte Mask Signal Output Output Output Output Output CompactFlash Support CFCE1 - CFCE2 CFOE CFWE CFIOR CFIOW CFRNW CFCS0 - CFCS1 CompactFlash Chip Enable CompactFlash Output Enable CompactFlash Write Enable CompactFlash IO Read CompactFlash IO Write CompactFlash Read Not Write CompactFlash Chip Select Lines Output Output Output Output Output Output Output Low Low Low Low Low Low Low Low Low Low Low 6 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Table 3-1. Signal Name Signal Description List (Continued) Function Type NAND Flash Support Active Level Comments NANDCS NANDOE NANDWE NANDALE NANDCLE NAND Flash Chip Select NAND Flash Output Enable NAND Flash Write Enable NAND Flash Address Latch Enable NAND Flash Command Latch Enable Output Output Output Output Output Low Low Low Low Low SDRAM Controller SDCK SDCKE SDCS BA0 - BA1 SDWE RAS - CAS SDA10 SDRAM Clock SDRAM Clock Enable SDRAM Controller Chip Select Bank Select SDRAM Write Enable Row and Column Signal SDRAM Address 10 Line Output Output Output Output Output Output Output Low Low High Low Multimedia Card Interface MCI MCCK MCCDA MCDA0 - MCDA3 MCCDB MCDB0 - MCDB3 Multimedia Card Clock Multimedia Card Slot A Command Multimedia Card Slot A Data Multimedia Card Slot B Command Multimedia Card Slot B Data Output I/O I/O I/O I/O Universal Synchronous Asynchronous Receiver Transmitter USARTx SCKx TXDx RXDx RTSx CTSx DTR0 DSR0 DCD0 RI0 USARTx Serial Clock USARTx Transmit Data USARTx Receive Data USARTx Request To Send USARTx Clear To Send USART0 Data Terminal Ready USART0 Data Set Ready USART0 Data Carrier Detect USART0 Ring Indicator I/O I/O Input Output Input Output Input Input Input Synchronous Serial Controller - SSC TD RD TK RK TF RF SSC Transmit Data SSC Receive Data SSC Transmit Clock SSC Receive Clock SSC Transmit Frame Sync SSC Receive Frame Sync Output Input I/O I/O I/O I/O 7 6384D–ATARM–04-May-09 Table 3-1. Signal Name Signal Description List (Continued) Function Type Timer/Counter - TCx Active Level Comments TCLKx TIOAx TIOBx TC Channel x External Clock Input TC Channel x I/O Line A TC Channel x I/O Line B Input I/O I/O Serial Peripheral Interface - SPIx_ SPIx_MISO SPIx_MOSI SPIx_SPCK SPIx_NPCS0 SPIx_NPCS1-SPIx_NPCS3 Master In Slave Out Master Out Slave In SPI Serial Clock SPI Peripheral Chip Select 0 SPI Peripheral Chip Select I/O I/O I/O I/O Output Low Low Two-Wire Interface TWD TWCK Two-wire Serial Data Two-wire Serial Clock USB Host Port HDPA HDMA HDPB HDMB USB Host Port A Data + USB Host Port A Data USB Host Port B Data + USB Host Port B Data USB Device Port DDM DDP USB Device Port Data USB Device Port Data + Ethernet 10/100 ETXCK ERXCK ETXEN ETX0-ETX3 ETXER ERXDV ERX0-ERX3 ERXER ECRS ECOL EMDC EMDIO Transmit Clock or Reference Clock Receive Clock Transmit Enable Transmit Data Transmit Coding Error Receive Data Valid Receive Data Receive Error Carrier Sense and Data Valid Collision Detect Management Data Clock Management Data Input/Output Input Input Output Output Output Input Input Input Input Input Output I/O MII only MII only ETX0-ETX1 only in RMII MII only RXDV in MII, CRSDV in RMII ERX0-ERX1 only in RMII MII only, REFCK in RMII MII only Analog Analog Analog Analog Analog Analog I/O I/O 8 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Table 3-1. Signal Name Signal Description List (Continued) Function Type Image Sensor Interface Active Level Comments ISI_D0-ISI_D11 ISI_MCK ISI_HSYNC ISI_VSYNC ISI_PCK Image Sensor Data Image Sensor Reference Clock Image Sensor Horizontal Synchro Image Sensor Vertical Synchro Image Sensor Data clock Input Output Input Input Input Analog to Digital Converter AD0-AD3 ADVREF ADTRG Note: Analog Inputs Analog Positive Reference ADC Trigger No PLLRCA line present on the AT91SAM9G20. Analog Analog Input Digital pulled-up inputs at reset 4. Package and Pinout • The AT91SAM9G20 is available in a 217-ball, 15 x 15 mm, LFBGA package (0.8 mm pitch) (Figure 4-1). • The AT91SAM9G20 is available in a 247-ball, 10 x 10 x 1.1 mm, TFBGA Green package, (0.5 mm pitch) (Figure 4-1). 4.1 217-ball LFBGA Package Outline Figure 4-1 shows the orientation of the 217-ball LFBGA package. A detailed mechanical description is given in the section “AT91SAM9G20 Mechanical Characteristics” of the product datasheet. Figure 4-1. 217-ball LFBGA Package (Top View) 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 ABCDEFGH J K LMNPRTU Ball A1 9 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 4.2 Pin A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12 A13 A14 A15 A16 A17 B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 B11 B12 B13 B14 B15 B16 B17 C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12 C13 C14 C15 C16 C17 D1 D2 D3 D4 217-ball LFBGA Pinout Pinout for 217-ball LFBGA Package Signal Name CFIOW/NBS3/NWR3 NBS0/A0 NWR2/NBS2/A1 A6 A8 A11 A13 BA0/A16 A18 A21 A22 CFWE/NWE/NWR0 CFOE/NRD NCS0 PC5 PC6 PC4 SDCK CFIOR/NBS1/NWR1 SDCS/NCS1 SDA10 A3 A7 A12 A15 A20 NANDWE PC7 PC10 PC13 PC11 PC14 PC8 WKUP D8 D1 CAS A2 A4 A9 A14 BA1/A17 A19 NANDOE PC9 PC12 DDP HDMB NC VDDUSB SHDN D9 D2 RAS D0 Table 4-1. Pin D5 D6 D7 D8 D9 D10 D11 D12 D13 D14 D15 D16 D17 E1 E2 E3 E4 E14 E15 E16 E17 F1 F2 F3 F4 F14 F15 F16 F17 G1 G2 G3 G4 G14 G15 G16 G17 H1 H2 H3 H4 H8 H9 H10 H14 H15 H16 H17 J1 J2 J3 J4 J8 J9 J10 Signal Name A5 GND A10 GND VDDCORE GNDUSB VDDIOM GNDUSB DDM HDPB NC VDDBU XIN32 D10 D5 D3 D4 HDPA HDMA GNDBU XOUT32 D13 SDWE D6 GND OSCSEL BMS JTAGSEL TST PC15 D7 SDCKE VDDIOM GND NRST RTCK TMS PC18 D14 D12 D11 GND GND GND VDDCORE TCK NTRST PB18 PC19 PC17 VDDIOM PC16 GND GND GND Pin J14 J15 J16 J17 K1 K2 K3 K4 K8 K9 K10 K14 K15 K16 K17 L1 L2 L3 L4 L14 L15 L16 L17 M1 M2 M3 M4 M14 M15 M16 M17 N1 N2 N3 N4 N14 N15 N16 N17 P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 P12 P13 P14 P15 P16 Signal Name TDO PB19 TDI PB16 PC24 PC20 D15 PC21 GND GND GND PB4 PB17 GND PB15 GND PC26 PC25 VDDOSC PA28 PB9 PB8 PB14 VDDCORE PC31 GND PC22 PB1 PB2 PB3 PB7 XIN VDDPLL PC23 PC27 PA31 PA30 PB0 PB6 XOUT VDDPLL PC30 PC28 PB11 PB13 PB24 VDDIOP PB30 PB31 PA1 PA3 PA7 PA9 PA26 PA25 Pin P17 R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 R11 R12 R13 R14 R15 R16 R17 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 T13 T14 T15 T16 T17 U1 U2 U3 U4 U5 U6 U7 U8 U9 U10 U11 U12 U13 U14 U15 U16 U17 Signal Name PB5 NC GNDANA PC29 VDDANA PB12 PB23 GND PB26 PB28 PA0 PA4 PA5 PA10 PA21 PA23 PA24 PA29 NC GNDPLL PC0 PC1 PB10 PB22 GND PB29 PA2 PA6 PA8 PA11 VDDCORE PA20 GND PA22 PA27 GNDPLL ADVREF PC2 PC3 PB20 PB21 PB25 PB27 PA12 PA13 PA14 PA15 PA19 PA17 PA16 PA18 VDDIOP 10 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 4.3 247-ball TFBGA Package Outline Figure 4-2 shows the orientation of the 247-ball TFBGA package. A detailed mechanical description is given in the section “AT91SAM9G20 Mechanical Characteristics” of the product datasheet. Figure 4-2. 247-ball TFBGA Package (Top View) Ball A1 1 A B C D E F G H J K L M N P R T U V W 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 11 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 4.4 Pin A1 A2 A12 A14 A16 A18 A19 B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 B11 B13 B15 B17 B19 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12 C14 C16 C18 D2 D3 D13 D15 D17 D19 E2 E3 E5 E6 E7 E8 E9 E10 E11 E12 E13 E14 E15 E16 E18 E19 F2 F3 F5 F6 247-ball TFBGA Package Pinout Pinout for 247-ball TFBGA Package Signal Name D13 D12 A9 A13 A20 A22 NANDOE D15 D14 D10 D9 D7 D3 D2 RAS CAS NWR2/NBS2/A1 A3 A10 A18 A21 VDDUSB PC15 D11 D8 SDCKE SDWE SDCK D1 SDCS/NCS1 A2 A7 A11 A19 GNDUSB CFWE/NWE/NWR0 PC17 PC16 A14 NANDWE CFOE/NRD NCS0 PC18 PC19 D6 D5 D0 CFIOW/NBS3/NWR3 GND A4 A8 VDDIOM BA0/A16 PC8 PC4 PC5 PC7 PC6 PC22 PC23 PC20 D4 Table 4-2. Pin F7 F8 F9 F10 F11 F12 F13 F14 F15 F16 F17 F18 G2 G3 G5 G6 G8 G9 G10 G11 G12 G14 G15 G17 G18 H2 H3 H5 H6 H7 H8 H9 H10 H11 H12 H13 H14 H15 H17 H18 J2 J3 J5 J6 J7 J8 J9 J10 J11 J12 J13 J14 J15 J17 J18 K2 K3 K5 K6 K7 K8 K9 Signal Name CFIOR/NBS1/NWR1 SDA10 NBS0/A0 A6 A12 A15 BA1/A17 PC10 PC14 VDDUSB PC9 PC12 PC26 PC25 PC24 PC21 VDDCORE A5 VDDCORE VDDCORE VDDCORE PC13 GND GNDUSB PC11 PC31 PC30 PC28 PC27 PC29 GND GND VDDIOM VDDIOM GND VDDCORE SHDW VDDBU HDPB HDMB VDDOSC VDDPLL XOUT XIN VDDPLL GND VDDIOM VDDIOM VDDIOM GND GND WKUP DDP DDM VDDIOP GNDPLL GND NC GNDPLL VDDANA GND GND Pin K10 K11 K12 K13 K14 K15 K17 K18 L2 L3 L5 L6 L7 L8 L9 L10 L11 L12 L13 L14 L15 L17 L18 M2 M3 M5 M6 M7 M8 M9 M10 M11 M12 M13 M14 M15 M17 M18 N2 N3 N5 N6 N8 N11 N12 N14 N15 N17 N18 P2 P3 P5 P6 P7 P8 P9 P10 P11 P12 P13 P14 P15 Signal Name GND VDDIOM GND GND XOUT32 XIN32 HDPA HDMA NC NC ADVREF PC2 GND GND GND GND VDDCORE GND OSCSEL GNDBU GND NRST TCK PC0 PC1 PC3 NTRST GND GND GND PA16 VDDCORE GND VDDIOP TST JTAGSEL PB18 TMS PB20 PB13 PB11 BMS GND PA17 PA23 GND VDDIOP TDO TDI PB24 PB22 GND GND PA6 PA7 PA11 GND PA18 PA24 PA28 PB3 PB5 Pin P17 P18 R2 R3 R5 R6 R7 R8 R9 R10 R11 R12 R13 R14 R15 R17 R18 T2 T3 T17 T18 U2 U3 U4 U5 U6 U7 U8 U9 U10 U11 U12 U13 U14 U15 U16 U17 U18 V1 V2 V3 V4 V5 V6 V7 V8 V9 V10 V11 V12 V13 V14 V15 V16 V17 V18 V19 W1 W2 W18 W19 Signal Name RTCK PB16 GND PB29 PB26 PB27 PA5 GND PA12 GND PA19 PA26 PB1 GND PB7 PB14 PB9 PA1 PB10 PB19 PB17 GNDANA PB21 PB28 PB31 PA4 PA3 PA9 GND PA15 PA21 PA25 PA29 PA27 PA31 GND PB2 GND PB12 PB23 PB30 PA2 PA8 PA10 PA13 VDDIOP PA14 VDDIOP PA20 PA22 VDDIOP PA30 PB0 GND PB4 GND PB6 PB25 PA0 PB8 PB15 12 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 5. Power Considerations 5.1 Power Supplies The AT91SAM9G20 has several types of power supply pins: • VDDCORE pins: Power the core, including the processor, the embedded memories and the peripherals; voltage ranges from 0.9V to 1.1V, 1.0V nominal. • VDDIOM pins: Power the External Bus Interface I/O lines; voltage ranges between 1.65V and 1.95V (1.8V typical) or between 3.0V and 3.6V (3.3V nominal). The voltage range is selectable by software. • VDDIOP pins: Power the Peripherals I/O lines; voltage ranges from 1.65V to 3.6V. • VDDBU pin: Powers the Slow Clock oscillator, the internal RC oscillator and a part of the System Controller; voltage ranges from 0.9V to 1.1V, 1.0V nominal. • VDDPLL pin: Powers the PLL cells; voltage ranges from 0.9V to 1.1V. • VDDOSC pin: Powers the Main Oscillator cells; voltage ranges from 1.65V to 3.6V • VDDANA pin: Powers the Analog to Digital Converter; voltage ranges from 3.0V to 3.6V, 3.3V nominal. • VDDUSB pin: Powers USB transceiver; voltage ranges from 3.0V to 3.6V. Ground pins GND are common to VDDCORE, VDDIOM, VDDOSC and VDDIOP pins power supplies. Separated ground pins are provided for VDDBU, VDDPLL, VDDUSB and VDDANA. These ground pins are respectively GNDBU, GNDPLL, GNDUSB and GNDANA. 5.2 Power Consumption The AT91SAM9G20 consumes about 4 mA of static current on VDDCORE at 25°C. This static current rises at up to 18 mA if the temperature increases to 85°C. On VDDBU, the current does not exceed 9 µA at 25°C. This static current rises at up to 18 µA if the temperature increases to 85°C. For dynamic power consumption, the AT91SAM9G20 consumes a maximum of 50 mA on VDDCORE at maximum conditions (1.0V, 25°C, rises to 80mA at 85°C, processor running fullperformance algorithm out of high-speed memories). 5.3 Programmable I/O Lines The power supplies pins VDDIOM accept two voltage ranges. This allows the device to reach its maximum speed either out of 1.8V or 3.3V external memories. The maximum speed is 133 MHz on the pin SDCK (SDRAM Clock) loaded with 10 pF. The other signals (control, address and data signals) do not go over 66 MHz, loaded with 30 pF for power supply at 1.8V and 50 pF for power supply at 3.3V. The EBI I/Os accept two slew rate modes, Fast and Slow. This allows to adapt the rising and falling time on SDRAM clock, control and data to the bus load. The voltage ranges and the slew rates are determined by programming VDDIOMSEL and IOSR bits in the Chip Configuration registers located in the Matrix User Interface. At reset, the selected voltage defaults to 3.3V nominal and power supply pins can accept either 1.8V or 3.3V. The user must make sure to program the EBI voltage range before getting the device out of its Slow Clock Mode. At reset, the selected slew rates defaults are Fast. 13 6384D–ATARM–04-May-09 6. I/O Line Considerations 6.1 JTAG Port Pins TMS, TDI and TCK are schmitt trigger inputs and have no pull-up resistors. TDO and RTCK are outputs, driven at up to VDDIOP, and have no pull-up resistor. The JTAGSEL pin is used to select the JTAG boundary scan when asserted at a high level. It integrates a permanent pull-down resistor of about 15 kΩ to GND, so that it can be left unconnected for normal operations. The NTRST signal is described in the Reset Pins paragraph. All the JTAG signals are supplied with VDDIOP. 6.2 Test Pin The TST pin is used for manufacturing test purposes when asserted high. It integrates a permanent pull-down resistor of about 15 kΩ to GNDBU, so that it can be left unconnected for normal operations. Driving this line at a high level leads to unpredictable results. This pin is supplied with VDDBU. 6.3 Reset Pins NRST is an open-drain output integrating a non-programmable pull-up resistor. It can be driven with voltage at up to VDDIOP. NTRST is an input which allows reset of the JTAG Test Access port. It has no action on the processor. As the product integrates power-on reset cells, which manages the processor and the JTAG reset, the NRST and NTRST pins can be left unconnected. The NRST and NTRST pins both integrate a permanent pull-up resistor of 100 kΩ minimum to VDDIOP. The NRST signal is inserted in the Boundary Scan. 6.4 PIO Controllers All the I/O lines are Schmitt trigger inputs and all the lines managed by the PIO Controllers integrate a programmable pull-up resistor of 75 kΩ typical with the exception of P4 - P31. For details, refer to the section “AT91SAM9G20 Electrical Characteristics”. Programming of this pull-up resistor is performed independently for each I/O line through the PIO Controllers. 6.5 I/O Line Drive Levels The PIO lines drive current capability is described in the DC Characteristics section of the product datasheet. 6.6 Shutdown Logic Pins The SHDN pin is a tri-state output only pin, which is driven by the Shutdown Controller. There is no internal pull-up. An external pull-up to VDDBU is needed and its value must be higher than 1 MΩ. The resistor value is calculated according to the regulator enable implementation and the SHDN level. 14 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary The pin WKUP is an input-only. It can accept voltages only between 0V and VDDBU. 6.7 Slow Clock Selection The AT91SAM9G20 slow clock can be generated either by an external 32768Hz crystal or the on-chip RC oscillator. 7. Processor and Architecture 7.1 ARM926EJ-S Processor • RISC Processor Based on ARM v5TEJ Architecture with Jazelle technology for Java acceleration • Two Instruction Sets – ARM High-performance 32-bit Instruction Set – Thumb High Code Density 16-bit Instruction Set • DSP Instruction Extensions • 5-Stage Pipeline Architecture: – Instruction Fetch (F) – Instruction Decode (D) – Execute (E) – Data Memory (M) – Register Write (W) • 32-Kbyte Data Cache, 32-Kbyte Instruction Cache – Virtually-addressed 4-way Associative Cache – Eight words per line – Write-through and Write-back Operation – Pseudo-random or Round-robin Replacement • Write Buffer – Main Write Buffer with 16-word Data Buffer and 4-address Buffer – DCache Write-back Buffer with 8-word Entries and a Single Address Entry – Software Control Drain • Standard ARM v4 and v5 Memory Management Unit (MMU) – Access Permission for Sections – Access Permission for large pages and small pages can be specified separately for each quarter of the page – 16 embedded domains • Bus Interface Unit (BIU) – Arbitrates and Schedules AHB Requests – Separate Masters for both instruction and data access providing complete Matrix system flexibility – Separate Address and Data Buses for both the 32-bit instruction interface and the 32-bit data interface 15 6384D–ATARM–04-May-09 – On Address and Data Buses, data can be 8-bit (Bytes), 16-bit (Half-words) or 32-bit (Words) 7.2 Bus Matrix • 6-layer Matrix, handling requests from 6 masters • Programmable Arbitration strategy – Fixed-priority Arbitration – Round-Robin Arbitration, either with no default master, last accessed default master or fixed default master • Burst Management – Breaking with Slot Cycle Limit Support – Undefined Burst Length Support • One Address Decoder provided per Master – Three different slaves may be assigned to each decoded memory area: one for internal boot, one for external boot, one after remap • Boot Mode Select – Non-volatile Boot Memory can be internal or external – Selection is made by BMS pin sampled at reset • Remap Command – Allows Remapping of an Internal SRAM in Place of the Boot Non-Volatile Memory • Allows Handling of Dynamic Exception Vectors 7.2.1 Matrix Masters The Bus Matrix of the AT91SAM9G20 manages six Masters, which means that each master can perform an access concurrently with others, according the slave it accesses is available. Each Master has its own decoder that can be defined specifically for each master. In order to simplify the addressing, all the masters have the same decodings. Table 7-1. Master 0 Master 1 Master 2 Master 3 Master 4 Master 5 List of Bus Matrix Masters ARM926™ Instruction ARM926 Data PDC ISI Controller Ethernet MAC USB Host DMA 7.2.2 Matrix Slaves Each Slave has its own arbiter, thus allowing to program a different arbitration per Slave. Table 7-2. Slave 0 Slave 1 List of Bus Matrix Slaves Internal SRAM0 16 KBytes Internal SRAM1 16 KBytes 16 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Table 7-2. Slave 2 Slave 3 Slave 4 List of Bus Matrix Slaves (Continued) Internal ROM USB Host User Interface External Bus Interface Internal Peripherals 7.2.3 Masters to Slaves Access All the Masters can normally access all the Slaves. However, some paths do not make sense, like as example allowing access from the Ethernet MAC to the Internal Peripherals. Thus, these paths are forbidden or simply not wired, and shown “-” in Table 7-3. Table 7-3. AT91SAM9G20 Masters to Slaves Access Master Slave Internal SRAM 16 Kbytes Internal SRAM 16 Kbytes Internal ROM 2 UHP User Interface 3 4 External Bus Interface Internal Peripherals X X X X X X X X X 0&1 ARM926 Instruction & Data X X X 2 Peripheral DMA Controller X X X 3 ISI Controller X X 4 Ethernet MAC X X 5 USB Host Controller X X - 0 1 7.3 Peripheral DMA Controller • Acting as one Matrix Master • Allows data transfers from/to peripheral to/from any memory space without any intervention of the processor. • Next Pointer Support, forbids strong real-time constraints on buffer management. • Twenty-four channels – Two for each USART – Two for the Debug Unit – Two for the Serial Synchronous Controller – Two for each Serial Peripheral Interface – One for Multimedia Card Interface – One for Analog-to-Digital Converter – Two for the Two-wire Interface The Peripheral DMA Controller handles transfer requests from the channel according to the following priorities (Low to High priorities): – TWI Transmit Channel – DBGU Transmit Channel – USART5 Transmit Channel 17 6384D–ATARM–04-May-09 – USART4 Transmit Channel – USART3 Transmit Channel – USART2 Transmit Channel – USART1 Transmit Channel – USART0 Transmit Channel – SPI1 Transmit Channel – SPI0 Transmit Channel – SSC Transmit Channel – TWI Receive Channel – DBGU Receive Channel – USART5 Receive Channel – USART4 Receive Channel – USART3 Receive Channel – USART2 Receive Channel – USART1 Receive Channel – USART0 Receive Channel – ADC Receive Channel – SPI1 Receive Channel – SPI0 Receive Channel – SSC Receive Channel – MCI Transmit/Receive Channel 7.4 Debug and Test Features • ARM926 Real-time In-circuit Emulator – Two real-time Watchpoint Units – Two Independent Registers: Debug Control Register and Debug Status Register – Test Access Port Accessible through JTAG Protocol – Debug Communications Channel • Debug Unit – Two-pin UART – Debug Communication Channel Interrupt Handling – Chip ID Register • IEEE1149.1 JTAG Boundary-scan on All Digital Pins 18 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 8. Memories Figure 8-1. AT91SAM9G20 Memory Mapping Address Memory Space 0x0000 0000 Internal Memories 0x0FFF FFFF Internal Memory Mapping 0x0000 0000 Boot Memory (1) Notes : (1) Can be ROM, EBI_NCS0 or SRAM depending on BMS and REMAP 256M Bytes 0x10 0000 ROM 0x10 8000 Reserved 32K Bytes 0x1000 0000 EBI Chip Select 0 0x1FFF FFFF 256M Bytes 0x20 0000 SRAM0 0x20 4000 Reserved 16K Bytes 0x2000 0000 EBI Chip Select 1/ SDRAMC 256M Bytes 0x30 0000 SRAM1 0x30 4000 Reserved 0x50 0000 16K Bytes 0x2FFF FFFF 0x3000 0000 EBI Chip Select 2 0x3FFF FFFF 256M Bytes UHP 0x50 4000 Reserved 16K Bytes 0x4000 0000 EBI Chip Select 3/ NANDFlash EBI Chip Select 4/ Compact Flash Slot 0 EBI Chip Select 5/ Compact Flash Slot 1 EBI Chip Select 6 256M Bytes 0x0FFF FFFF 0x4FFF FFFF 0x5000 0000 256M Bytes 0x5FFF FFFF 0x6000 0000 Peripheral Mapping 256M Bytes 0xF000 0000 0x6FFF FFFF 0x7000 0000 256M Bytes Reserved 0xFFFA 0000 TCO, TC1, TC2 0xFFFA 4000 UDP 0xFFFA 8000 16K Bytes 16K Bytes System Controller Mapping 0xFFFF C000 Reserved 0xFFFF E800 ECC 512 Bytes 0x7FFF FFFF 0x8000 0000 EBI Chip Select 7 0x8FFF FFFF 256M Bytes 0xFFFA C000 MCI TWI 0xFFFB 0000 USART0 0xFFFB 4000 USART1 0xFFFB 8000 USART2 0xFFFB C000 SSC 0xFFFC 0000 ISI 0xFFFC 4000 EMAC 0xFFFC 8000 16K Bytes 16K Bytes 0xFFFF EA00 SDRAMC 0xFFFF EC00 512 Bytes 0x9000 0000 16K Bytes 0xFFFF EE00 16K Bytes 16K Bytes 16K Bytes 16K Bytes 16K Bytes 0xFFFF F600 16K Bytes 16K Bytes 0xFFFF F800 SMC MATRIX 0xFFFF EF10 0xFFFF F000 CCFG AIC 0xFFFF F200 DBGU 0xFFFF F400 PIOA 512 Bytes 512 Bytes 512 Bytes 512 Bytes 512 Bytes Undefined (Abort) 1,518M Bytes 0xFFFC C000 SPI0 PIOB 512 bytes SPI1 0xFFFD 0000 USART3 0xFFFD 4000 USART4 0xFFFD 8000 USART5 0xFFFD C000 TC3, TC4, TC5 0xFFFE 0000 0xEFFF FFFF ADC 0xFFFE 4000 PIOC 16K Bytes 16K Bytes 16K Bytes 0xFFFF FA00 Reserved 0xFFFF FC00 PMC 0xFFFF FD00 RSTC 0xFFFF FD10 16K Bytes 16K Bytes 0xFFFF FD20 0xFFFF FD30 0xFFFF FD40 WDTC SHDC RTTC PITC 0xFFFF FD50 0xFFFF FD60 16K Bytes 0xFFFF FFFF 512 bytes 256 Bytes 16 Bytes 16 Bytes 16 Bytes 16 Bytes 16 Bytes 16 Bytes 0xF000 0000 Internal Peripherals 0xFFFF FFFF Reserved 256M Bytes 0xFFFF C000 SYSC 0xFFFF FFFF GPBR Reserved 19 6384D–ATARM–04-May-09 A first level of address decoding is performed by the Bus Matrix, i.e., the implementation of the Advanced High Performance Bus (AHB) for its Master and Slave interfaces with additional features. Decoding breaks up the 4G bytes of address space into 16 banks of 256 Mbytes. The banks 1 to 7 are directed to the EBI that associates these banks to the external chip selects EBI_NCS0 to EBI_NCS7. Bank 0 is reserved for the addressing of the internal memories, and a second level of decoding provides 1 Mbyte of internal memory area. Bank 15 is reserved for the peripherals and provides access to the Advanced Peripheral Bus (APB). Other areas are unused and performing an access within them provides an abort to the master requesting such an access. Each Master has its own bus and its own decoder, thus allowing a different memory mapping per Master. However, in order to simplify the mappings, all the masters have a similar address decoding. Regarding Master 0 and Master 1 (ARM926 Instruction and Data), three different Slaves are assigned to the memory space decoded at address 0x0: one for internal boot, one for external boot, one after remap. Refer to Table 8-1, “Internal Memory Mapping,” on page 20 for details. A complete memory map is presented in Figure 8-1 on page 19. 8.1 Embedded Memories • 64-KByte ROM – Single Cycle Access at full matrix speed • Two 16-Kbyte Fast SRAM – Single Cycle Access at full matrix speed 8.1.1 Boot Strategies Table 8-1 summarizes the Internal Memory Mapping for each Master, depending on the Remap status and the BMS state at reset. Table 8-1. Internal Memory Mapping REMAP = 0 Address BMS = 1 0x0000 0000 0x0010 0000 0x0020 0000 0x0030 0000 0x0050 0000 ROM BMS = 0 EBI_NCS0 ROM SRAM0 16K SRAM1 16K USB Host User Interface SRAM0 16K REMAP = 1 The system always boots at address 0x0. To ensure a maximum number of possibilities for boot, the memory layout can be configured with two parameters. REMAP allows the user to lay out the first internal SRAM bank to 0x0 to ease development. This is done by software once the system has booted. When REMAP = 1, BMS is ignored. Refer to the Bus Matrix Section for more details. 20 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary When REMAP = 0, BMS allows the user to lay out to 0x0, at his convenience, the ROM or an external memory. This is done via hardware at reset. Note: Memory blocks not affected by these parameters can always be seen at their specified base addresses. See the complete memory map presented in Figure 8-1 on page 19. The AT91SAM9G20 matrix manages a boot memory that depends on the level on the BMS pin at reset. The internal memory area mapped between address 0x0 and 0x000F FFFF is reserved for this purpose. If BMS is detected at 1, the boot memory is the embedded ROM. If BMS is detected at 0, the boot memory is the memory connected on the Chip Select 0 of the External Bus Interface. 8.1.1.1 BMS = 1, Boot on Embedded ROM The system boots using the Boot Program. • Boot on slow clock (On-chip RC or 32,768 Hz) • Auto baudrate detection • Downloads and runs an application from external storage media into internal SRAM • Downloaded code size depends on embedded SRAM size • Automatic detection of valid application • Bootloader on a non-volatile memory – SDCard (boot ROM does not support high capacity SDCards.) – NAND Flash – SPI DataFlash® and Serial Flash connected on NPCS0 and NPCS1 of the SPI0 – EEPROM on TWI • SAM-BA® Boot in case no valid program is detected in external NVM, supporting – Serial communication on a DBGU – USB Device HS Port 8.1.1.2 BMS = 0, Boot on External Memory • Boot on slow clock (On-chip RC or 32,768 Hz) • Boot with the default configuration for the Static Memory Controller, byte select mode, 16-bit data bus, Read/Write controlled by Chip Select, allows boot on 16-bit non-volatile memory. The customer-programmed software must perform a complete configuration. To speed up the boot sequence when booting at 32 kHz EBI CS0 (BMS=0), the user must take the following steps: 1. Program the PMC (main oscillator enable or bypass mode). 2. Program and start the PLL. 3. Reprogram the SMC setup, cycle, hold, mode timings registers for CS0 to adapt them to the new clock. 4. Switch the main clock to the new value. 8.2 External Memories The external memories are accessed through the External Bus Interface. Each Chip Select line has a 256-Mbyte memory area assigned. 21 6384D–ATARM–04-May-09 Refer to the memory map in Figure 8-1 on page 19. 8.2.1 External Bus Interface • Integrates three External Memory Controllers – Static Memory Controller – SDRAM Controller – ECC Controller • Additional logic for NAND Flash • Full 32-bit External Data Bus • Up to 26-bit Address Bus (up to 64MBytes linear) • Up to 8 chip selects, Configurable Assignment: – Static Memory Controller on NCS0 – SDRAM Controller or Static Memory Controller on NCS1 – Static Memory Controller on NCS2 – Static Memory Controller on NCS3, Optional NAND Flash support – Static Memory Controller on NCS4 - NCS5, Optional CompactFlash support – Static Memory Controller on NCS6-NCS7 8.2.2 Static Memory Controller • 8-, 16- or 32-bit Data Bus • Multiple Access Modes supported – Byte Write or Byte Select Lines – Asynchronous read in Page Mode supported (4- up to 32-byte page size) • Multiple device adaptability – Compliant with LCD Module – Control signals programmable setup, pulse and hold time for each Memory Bank • Multiple Wait State Management – Programmable Wait State Generation – External Wait Request – Programmable Data Float Time • Slow Clock mode supported 8.2.3 SDRAM Controller • Supported devices – Standard and Low-power SDRAM (Mobile SDRAM) • Numerous configurations supported – 2K, 4K, 8K Row Address Memory Parts – SDRAM with two or four Internal Banks – SDRAM with 16- or 32-bit Datapath • Programming facilities – Word, half-word, byte access – Automatic page break when Memory Boundary has been reached 22 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary – Multibank Ping-pong Access – Timing parameters specified by software – Automatic refresh operation, refresh rate is programmable • Energy-saving capabilities – Self-refresh, power down and deep power down modes supported • Error detection – Refresh Error Interrupt • SDRAM Power-up Initialization by software • CAS Latency of 1, 2 and 3 supported • Auto Precharge Command not used 8.2.4 Error Corrected Code Controller • Hardware Error Corrected Code (ECC) Generation – Detection and Correction by Software • Supports NAND Flash and SmartMedia™ Devices with 8- or 16-bit Data Path. • Supports NAND Flash/SmartMedia with Page Sizes of 528, 1056, 2112 and 4224 Bytes, Specified by Software • Supports 1 bit correction for a page of 512,1024,2048 and 4096 Bytes with 8- or 16-bit Data Path • Supports 1 bit correction per 512 bytes of data for a page size of 512, 2048 and 4096 Bytes with 8-bit Data Path • Supports 1 bit correction per 256 bytes of data for a page size of 512, 2048 and 4096 Bytes with 8-bit Data Path 9. System Controller The System Controller is a set of peripherals, which allow handling of key elements of the system, such as power, resets, clocks, time, interrupts, watchdog, etc. The System Controller User Interface embeds also the registers allowing to configure the Matrix and a set of registers for the chip configuration. The chip configuration registers allows configuring: – EBI chip select assignment and Voltage range for external memories The System Controller’s peripherals are all mapped within the highest 16 Kbytes of address space, between addresses 0xFFFF E800 and 0xFFFF FFFF. However, all the registers of System Controller are mapped on the top of the address space. All the registers of the System Controller can be addressed from a single pointer by using the standard ARM instruction set, as the Load/Store instruction has an indexing mode of ±4 Kbytes. Figure 9-1 on page 24 shows the System Controller block diagram. Figure 8-1 on page 19 shows the mapping of the User Interfaces of the System Controller peripherals. 23 6384D–ATARM–04-May-09 9.1 System Controller Block Diagram AT91SAM9G20 System Controller Block Diagram System Controller VDDCORE Powered irq0-irq2 fiq periph_irq[2..24] pit_irq rtt_irq wdt_irq dbgu_irq pmc_irq rstc_irq MCK periph_nreset dbgu_rxd MCK debug periph_nreset SLCK debug idle proc_nreset Periodic Interval Timer Watchdog Timer wdt_fault WDRPROC NRST VDDCORE POR por_ntrst jtag_nreset rstc_irq Reset Controller periph_nreset proc_nreset backup_nreset VDDBU Powered SLCK rtt_irq rtt_alarm UDPCK periph_clk[10] RC OSC SLOW CLOCK OSC SLCK int MAIN OSC PLLA PLLB MAINCK Power Management Controller Shut-Down Controller periph_nreset periph_irq[10] 4 General-Purpose Backup Registers USB Device Port UHPCK periph_clk[20] periph_nreset periph_irq[20] USB Host Port Debug Unit Advanced Interrupt Controller int por_ntrst ntrst ARM926EJ-S nirq nfiq Figure 9-1. dbgu_irq dbgu_txd pit_irq proc_nreset PCK debug jtag_nreset wdt_irq MCK periph_nreset Boundary Scan TAP Controller Bus Matrix VDDBU VDDBU POR SLCK backup_nreset SLCK SHDN WKUP backup_nreset rtt0_alarm OSCSEL XIN32 XOUT32 Real-Time Timer periph_clk[2..27] pck[0-1] PCK UDPCK UHPCK MCK XIN XOUT PLLACK PLLBCK periph_nreset pmc_irq idle periph_clk[6..24] periph_nreset periph_nreset periph_clk[2..4] dbgu_rxd PA0-PA31 PB0-PB31 PC0-PC31 PIO Controllers periph_irq[2..4] irq0-irq2 fiq dbgu_txd Embedded Peripherals periph_irq[6..24] in out enable 24 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 9.2 Reset Controller • Based on two Power-on-Reset cell – one on VDDBU and one on VDDCORE • Status of the last reset – Either general reset (VDDBU rising), wake-up reset (VDDCORE rising), software reset, user reset or watchdog reset • Controls the internal resets and the NRST pin output – Allows shaping a reset signal for the external devices 9.3 Shutdown Controller • Shutdown and Wake-Up logic – Software programmable assertion of the SHDWN pin – Deassertion Programmable on a WKUP pin level change or on alarm 9.4 Clock Generator • Embeds a Low Power 32768 Hz Slow Clock Oscillator and a Low power RC oscillator selectable with OSCSEL signal – Provides the permanent Slow Clock SLCK to the system • Embeds the Main Oscillator – Oscillator bypass feature – Supports 3 to 20 MHz crystals • Embeds 2 PLLs – The PLL A outputs 400-800 MHz clock – The PLL B outputs 100 MHz clock – Both integrate an input divider to increase output accuracy – PLL A and PLL B embed their own filters 25 6384D–ATARM–04-May-09 Figure 9-2. Clock Generator Block Diagram Clock Generator OSCSEL On Chip RC OSC XIN32 XOUT32 XIN XOUT Main Oscillator Main Clock MAINCK Slow Clock Oscillator Slow Clock SLCK PLL and Divider A PLL and Divider B PLLA Clock PLLACK PLLB Clock PLLBCK Status Control Power Management Controller 9.5 Power Management Controller • Provides: – the Processor Clock PCK – the Master Clock MCK, in particular to the Matrix and the memory interfaces.The MCK divider can be 1,2,4,6 – the USB Device Clock UDPCK – independent peripheral clocks, typically at the frequency of MCK – 2 programmable clock outputs: PCK0, PCK1 • Five flexible operating modes: – Normal Mode, processor and peripherals running at a programmable frequency – Idle Mode, processor stopped waiting for an interrupt – Slow Clock Mode, processor and peripherals running at low frequency – Standby Mode, mix of Idle and Backup Mode, peripheral running at low frequency, processor stopped waiting for an interrupt – Backup Mode, Main Power Supplies off, VDDBU powered by a battery 26 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Figure 9-3. AT91SAM9G20 Power Management Controller Block Diagram Divider /1,/2 Master Clock Controller SLCK MAINCK PLLACK PLLBCK Prescaler /1,/2,/4,.../64 Divider /1,/2,/4,/6 Peripherals Clock Controller ON/OFF Processor Clock Controller Idle Mode PCK int MCK periph_clk[..] Programmable Clock Controller SLCK MAINCK PLLACK PLLBCK ON/OFF Prescaler /1,/2,/4,...,/64 pck[..] USB Clock Controller PLLBCK Divider /1,/2,/4 ON/OFF UDPCK 9.6 Periodic Interval Timer • Includes a 20-bit Periodic Counter, with less than 1 µs accuracy • Includes a 12-bit Interval Overlay Counter • Real Time OS or Linux®/Windows CE® compliant tick generator 9.7 Watchdog Timer • 16-bit key-protected only-once-Programmable Counter • Windowed, prevents the processor being in a dead-lock on the watchdog access 9.8 Real-time Timer • Real-time Timer 32-bit free-running back-up Counter • Integrates a 16-bit programmable prescaler running on slow clock • Alarm Register capable of generating a wake-up of the system through the Shutdown Controller 9.9 General-purpose Back-up Registers • Four 32-bit backup general-purpose registers 9.10 Advanced Interrupt Controller • Controls the interrupt lines (nIRQ and nFIQ) of the ARM Processor • Thirty-two individually maskable and vectored interrupt sources 27 6384D–ATARM–04-May-09 – Source 0 is reserved for the Fast Interrupt Input (FIQ) – Source 1 is reserved for system peripherals – Programmable Edge-triggered or Level-sensitive Internal Sources – Programmable Positive/Negative Edge-triggered or High/Low Level-sensitive • Three External Sources plus the Fast Interrupt signal • 8-level Priority Controller – Drives the Normal Interrupt of the processor – Handles priority of the interrupt sources 1 to 31 – Higher priority interrupts can be served during service of lower priority interrupt • Vectoring – Optimizes Interrupt Service Routine Branch and Execution – One 32-bit Vector Register per interrupt source – Interrupt Vector Register reads the corresponding current Interrupt Vector • Protect Mode – Easy debugging by preventing automatic operations when protect models are enabled • Fast Forcing – Permits redirecting any normal interrupt source on the Fast Interrupt of the processor 9.11 Debug Unit • Composed of two functions: – Two-pin UART – Debug Communication Channel (DCC) support • Two-pin UART – Implemented features are 100% compatible with the standard Atmel ® USART – Independent receiver and transmitter with a common programmable Baud Rate Generator – Even, Odd, Mark or Space Parity Generation – Parity, Framing and Overrun Error Detection – Automatic Echo, Local Loopback and Remote Loopback Channel Modes – Support for two PDC channels with connection to receiver and transmitter • Debug Communication Channel Support – Offers visibility of and interrupt trigger from COMMRX and COMMTX signals from the ARM Processor’s ICE Interface 9.12 Chip Identification • Chip ID:0x019905A1 • JTAG ID: 0x05B2403F • ARM926 TAP ID:0x0792603F 28 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 10. Peripherals 10.1 User Interface The peripherals are mapped in the upper 256 Mbytes of the address space between the addresses 0xFFFA 0000 and 0xFFFC FFFF. Each User Peripheral is allocated 16 Kbytes of address space. A complete memory map is presented in Figure 8-1 on page 19. 10.2 Identifiers Table 10-1 defines the Peripheral Identifiers of the AT91SAM9G20. A peripheral identifier is required for the control of the peripheral interrupt with the Advanced Interrupt Controller and for the control of the peripheral clock with the Power Management Controller. Table 10-1. Peripheral ID 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 AT91SAM9G20 Peripheral Identifiers (Continued) Peripheral Mnemonic AIC SYSC PIOA PIOB PIOC ADC US0 US1 US2 MCI UDP TWI SPI0 SPI1 SSC TC0 TC1 TC2 UHP EMAC ISI US3 US4 US5 TC3 TC4 TC5 Peripheral Name Advanced Interrupt Controller System Controller Interrupt Parallel I/O Controller A Parallel I/O Controller B Parallel I/O Controller C Analog to Digital Converter USART 0 USART 1 USART 2 Multimedia Card Interface USB Device Port Two-wire Interface Serial Peripheral Interface 0 Serial Peripheral Interface 1 Synchronous Serial Controller Reserved Reserved Timer/Counter 0 Timer/Counter 1 Timer/Counter 2 USB Host Port Ethernet MAC Image Sensor Interface USART 3 USART 4 USART 5 Timer/Counter 3 Timer/Counter 4 Timer/Counter 5 External Interrupt FIQ 29 6384D–ATARM–04-May-09 Table 10-1. Peripheral ID 29 30 31 AT91SAM9G20 Peripheral Identifiers (Continued) Peripheral Mnemonic AIC AIC AIC Peripheral Name Advanced Interrupt Controller Advanced Interrupt Controller Advanced Interrupt Controller External Interrupt IRQ0 IRQ1 IRQ2 Note: Setting AIC, SYSC, UHP, ADC and IRQ0-2 bits in the clock set/clear registers of the PMC has no effect. The ADC clock is automatically started for the first conversion. In Sleep Mode the ADC clock is automatically stopped after each conversion. 10.2.1 10.2.1.1 Peripheral Interrupts and Clock Control System Interrupt The System Interrupt in Source 1 is the wired-OR of the interrupt signals coming from: • the SDRAM Controller • the Debug Unit • the Periodic Interval Timer • the Real-time Timer • the Watchdog Timer • the Reset Controller • the Power Management Controller The clock of these peripherals cannot be deactivated and Peripheral ID 1 can only be used within the Advanced Interrupt Controller. 10.2.1.2 External Interrupts All external interrupt signals, i.e., the Fast Interrupt signal FIQ or the Interrupt signals IRQ0 to IRQ2, use a dedicated Peripheral ID. However, there is no clock control associated with these peripheral IDs. 10.3 Peripheral Signal Multiplexing on I/O Lines The AT91SAM9G20 features 3 PIO controllers (PIOA, PIOB, PIOC) that multiplex the I/O lines of the peripheral set. Each PIO Controller controls up to 32 lines. Each line can be assigned to one of two peripheral functions, A or B. Table 10-2 on page 31, Table 10-3 on page 32 and Table 10-4 on page 33 define how the I/O lines of the peripherals A and B are multiplexed on the PIO Controllers. The two columns “Function” and “Comments” have been inserted in this table for the user’s own comments; they may be used to track how pins are defined in an application. Note that some peripheral functions which are output only might be duplicated within both tables. The column “Reset State” indicates whether the PIO Line resets in I/O mode or in peripheral mode. If I/O appears, the PIO Line resets in input with the pull-up enabled, so that the device is maintained in a static state as soon as the reset is released. As a result, the bit corresponding to the PIO Line in the register PIO_PSR (Peripheral Status Register) resets low. If a signal name appears in the “Reset State” column, the PIO Line is assigned to this function and the corresponding bit in PIO_PSR resets high. This is the case of pins controlling memories, in particular the address lines, which require the pin to be driven as soon as the reset is released. Note that the pull-up resistor is also enabled in this case. 30 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 10.3.1 PIO Controller A Multiplexing Multiplexing on PIO Controller A PIO Controller A I/O Line PA0 PA1 PA2 PA3 PA4 PA5 PA6 PA7 PA8 PA9 PA10 PA11 PA12 PA13 PA14 PA15 PA16 PA17 PA18 PA19 PA20 PA21 PA22 PA23 PA24 PA25 PA26 PA27 PA28 PA29 PA30 PA31 Peripheral A SPI0_MISO SPI0_MOSI SPI0_SPCK SPI0_NPCS0 RTS2 CTS2 MCDA0 MCCDA MCCK MCDA1 MCDA2 MCDA3 ETX0 ETX1 ERX0 ERX1 ETXEN ERXDV ERXER ETXCK EMDC EMDIO ADTRG TWD TWCK TCLK0 TIOA0 TIOA1 TIOA2 SCK1 SCK2 SCK0 ETXER ETX2 ETX3 ERX2 ERX3 ERXCK ECRS ECOL RXD4 TXD4 ETX2 ETX3 MCDB3 MCDB2 MCDB1 Peripheral B MCDB0 MCCDB Comments Reset State I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O Application Usage Power Supply VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP Function Comments Table 10-2. 31 6384D–ATARM–04-May-09 10.3.2 PIO Controller B Multiplexing Multiplexing on PIO Controller B PIO Controller B Application Usage Comments Reset State I/O I/O I/O I/O I/O I/O TCLK1 TCLK2 I/O I/O I/O I/O ISI_D8 ISI_D9 ISI_D10 ISI_D11 I/O I/O I/O I/O I/O I/O TCLK3 TCLK4 TIOB4 TIOB5 ISI_D0 ISI_D1 ISI_D2 ISI_D3 ISI_D4 ISI_D5 ISI_D6 ISI_D7 ISI_PCK ISI_VSYNC ISI_HSYNC ISI_MCK I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O Power Supply VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP VDDIOP Function Comments Table 10-3. I/O Line PB0 PB1 PB2 PB3 PB4 PB5 PB6 PB7 PB8 PB9 PB10 PB11 PB12 PB13 PB14 PB15 PB16 PB17 PB18 PB19 PB20 PB21 PB22 PB23 PB24 PB25 PB26 PB27 PB28 PB29 PB30 PB31 Peripheral A SPI1_MISO SPI1_MOSI SPI1_SPCK SPI1_NPCS0 TXD0 RXD0 TXD1 RXD1 TXD2 RXD2 TXD3 RXD3 TXD5 RXD5 DRXD DTXD TK0 TF0 TD0 RD0 RK0 RF0 DSR0 DCD0 DTR0 RI0 RTS0 CTS0 RTS1 CTS1 PCK0 PCK1 Peripheral B TIOA3 TIOB3 TIOA4 TIOA5 32 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 10.3.3 PIO Controller C Multiplexing Multiplexing on PIO Controller C PIO Controller C I/O Line PC0 PC1 PC2 PC3 PC4 PC5 PC6 PC7 PC8 PC9 PC10 PC11 PC12 PC13 PC14 PC15 PC16 PC17 PC18 PC19 PC20 PC21 PC22 PC23 PC24 PC25 PC26 PC27 PC28 PC29 PC30 PC31 A23 A24 TIOB2 TIOB1 NCS4/CFCS0 NCS5/CFCS1 A25/CFRNW NCS2 IRQ0 FIQ NCS3/NANDCS NWAIT D16 D17 D18 D19 D20 D21 D22 D23 D24 D25 D26 D27 D28 D29 D30 D31 TCLK5 Peripheral A Peripheral B SCK3 PCK0 PCK1 SPI1_NPCS3 SPI1_NPCS2 SPI1_NPCS1 CFCE1 CFCE2 RTS3 TIOB0 CTS3 SPI0_NPCS1 NCS7 NCS6 IRQ2 IRQ1 SPI0_NPCS2 SPI0_NPCS3 SPI1_NPCS1 SPI1_NPCS2 SPI1_NPCS3 Comments AD0 AD1 AD2 AD3 Reset State I/O I/O I/O I/O A23 A24 I/O I/O I/O I/O A25 I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O Application Usage Power Supply VDDANA VDDANA VDDANA VDDANA VDDIOM VDDIOM VDDIOM VDDIOM VDDIOM VDDIOM VDDIOM VDDIOM VDDIOM VDDIOM VDDIOM VDDIOM VDDIOM VDDIOM VDDIOM VDDIOM VDDIOM VDDIOM VDDIOM VDDIOM VDDIOM VDDIOM VDDIOM VDDIOM VDDIOM VDDIOM VDDIOM VDDIOM Function Comments Table 10-4. 33 6384D–ATARM–04-May-09 10.4 10.4.1 Embedded Peripherals Serial Peripheral Interface • Supports communication with serial external devices – Four chip selects with external decoder support allow communication with up to 15 peripherals – Serial memories, such as DataFlash and 3-wire EEPROMs – Serial peripherals, such as ADCs, DACs, LCD Controllers, CAN Controllers and Sensors – External co-processors • Master or slave serial peripheral bus interface – 8- to 16-bit programmable data length per chip select – Programmable phase and polarity per chip select – Programmable transfer delays between consecutive transfers and between clock and data per chip select – Programmable delay between consecutive transfers – Selectable mode fault detection • Very fast transfers supported – Transfers with baud rates up to MCK – The chip select line may be left active to speed up transfers on the same device 10.4.2 Two-wire Interface • Compatibility with standard two-wire serial memory • One, two or three bytes for slave address • Sequential read/write operations • Supports either master or slave modes • Compatible with standard two-wire serial memories • Master, multi-master and slave mode operation • Bit rate: up to 400 Kbits • General Call supported in slave mode • Connection to Peripheral DMA Controller (PDC) capabilities optimizes data transfers in master mode only – One channel for the receiver, one channel for the transmitter – Next buffer support 10.4.3 USART • Programmable Baud Rate Generator • 5- to 9-bit full-duplex synchronous or asynchronous serial communications – 1, 1.5 or 2 stop bits in Asynchronous Mode or 1 or 2 stop bits in Synchronous Mode – Parity generation and error detection – Framing error detection, overrun error detection – MSB- or LSB-first – Optional break generation and detection 34 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary – By 8 or by-16 over-sampling receiver frequency – Hardware handshaking RTS-CTS – Optional modem signal management DTR-DSR-DCD-RI – Receiver time-out and transmitter timeguard – Optional Multi-drop Mode with address generation and detection – Optional Manchester Encoding • RS485 with driver control signal • ISO7816, T = 0 or T = 1 Protocols for interfacing with smart cards – NACK handling, error counter with repetition and iteration limit • IrDA modulation and demodulation – Communication at up to 115.2 Kbps • Test Modes – Remote Loopback, Local Loopback, Automatic Echo The USART contains features allowing management of the Modem Signals DTR, DSR, DCD and RI. In the AT91SAM9G20, only the USART0 implements these signals, named DTR0, DSR0, DCD0 and RI0. The USART1 and USART2 do not implement all the modem signals. Only RTS and CTS (RTS1 and CTS1, RTS2 and CTS2, respectively) are implemented in these USARTs for other features. Thus, programming the USART1, USART2 or the USART3 in Modem Mode may lead to unpredictable results. In these USARTs, the commands relating to the Modem Mode have no effect and the status bits relating the status of the modem signals are never activated. 10.4.4 Serial Synchronous Controller • Provides serial synchronous communication links used in audio and telecom applications (with CODECs in Master or Slave Modes, I2S, TDM Buses, Magnetic Card Reader, etc.) • Contains an independent receiver and transmitter and a common clock divider • Offers a configurable frame sync and data length • Receiver and transmitter can be programmed to start automatically or on detection of different event on the frame sync signal • Receiver and transmitter include a data signal, a clock signal and a frame synchronization signal 10.4.5 Timer Counter • Two blocks of three 16-bit Timer Counter channels • Each channel can be individually programmed to perform a wide range of functions including: – Frequency Measurement – Event Counting – Interval Measurement – Pulse Generation – Delay Timing – Pulse Width Modulation – Up/down Capabilities • Each channel is user-configurable and contains: 35 6384D–ATARM–04-May-09 – Three external clock inputs – Five internal clock inputs – Two multi-purpose input/output signals • Each block contains two global registers that act on all three TC Channels Note: TC Block 0 (TC0, TC1, TC2) and TC Block 1 (TC3, TC4, TC5) have identical user interfaces. See Figure 8-1, “AT91SAM9G20 Memory Mapping,” on page 19 for TC Block 0 and TC Block 1 base addresses. 10.4.6 Multimedia Card Interface • One double-channel MultiMedia Card Interface • Compatibility with MultiMedia Card Specification Version 3.11 • Compatibility with SD Memory Card Specification Version 1.1 • Compatibility with SDIO Specification Version V1.0. • Card clock rate up to Master Clock divided by 2 • Embedded power management to slow down clock rate when not used • MCI has two slots, each supporting – One slot for one MultiMediaCard bus (up to 30 cards) or – One SD Memory Card • Support for stream, block and multi-block data read and write 10.4.7 USB Host Port • Compliance with Open HCI Rev 1.0 Specification • Compliance with USB V2.0 Full-speed and Low-speed Specification • Supports both Low-Speed 1.5 Mbps and Full-speed 12 Mbps devices • Root hub integrated with two downstream USB ports in the 217-LFBGA package • Two embedded USB transceivers • Supports power management • Operates as a master on the Matrix 10.4.8 USB Device Port • USB V2.0 full-speed compliant, 12 MBits per second • Embedded USB V2.0 full-speed transceiver • Embedded 2,432-byte dual-port RAM for endpoints • Suspend/Resume logic • Ping-pong mode (two memory banks) for isochronous and bulk endpoints • Six general-purpose endpoints – Endpoint 0 and 3: 64 bytes, no ping-pong mode – Endpoint 1 and 2: 64 bytes, ping-pong mode – Endpoint 4 and 5: 512 bytes, ping-pong mode • Embedded pad pull-up 10.4.9 Ethernet 10/100 MAC • Compatibility with IEEE Standard 802.3 36 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary • 10 and 100 MBits per second data throughput capability • Full- and half-duplex operations • MII or RMII interface to the physical layer • Register Interface to address, data, status and control registers • DMA Interface, operating as a master on the Memory Controller • Interrupt generation to signal receive and transmit completion • 28-byte transmit and 28-byte receive FIFOs • Automatic pad and CRC generation on transmitted frames • Address checking logic to recognize four 48-bit addresses • Support promiscuous mode where all valid frames are copied to memory • Support physical layer management through MDIO interface 10.4.10 Image Sensor Interface • ITU-R BT. 601/656 8-bit mode external interface support • Support for ITU-R BT.656-4 SAV and EAV synchronization • Vertical and horizontal resolutions up to 2048 x 2048 • Preview Path up to 640 x 480 in RGMB mode, 2048 x2048 in grayscale mode • Support for packed data formatting for YCbCr 4:2:2 formats • Preview scaler to generate smaller size image • Programmable frame capture rate 10.4.11 Analog-to-Digital Converter • 4-channel ADC • 10-bit 312K samples/sec. Successive Approximation Register ADC • -2/+2 LSB Integral Non Linearity, -1/+1 LSB Differential Non Linearity • Individual enable and disable of each channel • External voltage reference for better accuracy on low voltage inputs • Multiple trigger source – Hardware or software trigger – External trigger pin – Timer Counter 0 to 2 outputs TIOA0 to TIOA2 trigger • Sleep Mode and conversion sequencer – Automatic wakeup on trigger and back to sleep mode after conversions of all enabled channels • Four analog inputs shared with digital signals 37 6384D–ATARM–04-May-09 38 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 11. ARM926EJ-S Processor Overview 11.1 Overview The ARM926EJ-S processor is a member of the ARM9™ family of general-purpose microprocessors. The ARM926EJ-S implements ARM architecture version 5TEJ and is targeted at multitasking applications where full memory management, high performance, low die size and low power are all important features. The ARM926EJ-S processor supports the 32-bit ARM and 16-bit THUMB instruction sets, enabling the user to trade off between high performance and high code density. It also supports 8-bit Java instruction set and includes features for efficient execution of Java bytecode, providing a Java performance similar to a JIT (Just-In-Time compilers), for the next generation of Javapowered wireless and embedded devices. It includes an enhanced multiplier design for improved DSP performance. The ARM926EJ-S processor supports the ARM debug architecture and includes logic to assist in both hardware and software debug. The ARM926EJ-S provides a complete high performance processor subsystem, including: • an ARM9EJ-S™ integer core • a Memory Management Unit (MMU) • separate instruction and data AMBA AHB bus interfaces • separate instruction and data TCM interfaces 39 6384D–ATARM–04-May-09 11.2 Block Diagram Figure 11-1. ARM926EJ-S Internal Functional Block Diagram External Coprocessors ETM9 CP15 System Configuration Coprocessor External Coprocessor Interface Trace Port Interface Write Data ARM9EJ-S Processor Core Instruction Fetches Read Data Data Address MMU Instruction Address DTCM Interface Data TLB Instruction TLB ITCM Interface Data TCM Instruction TCM Data Address Data Cache AHB Interface and Write Buffer Instruction Address Instruction Cache AMBA AHB 40 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 11.3 11.3.1 ARM9EJ-S Processor ARM9EJ-S Operating States The ARM9EJ-S processor can operate in three different states, each with a specific instruction set: • ARM state: 32-bit, word-aligned ARM instructions. • THUMB state: 16-bit, halfword-aligned Thumb instructions. • Jazelle state: variable length, byte-aligned Jazelle instructions. In Jazelle state, all instruction Fetches are in words. 11.3.2 Switching State The operating state of the ARM9EJ-S core can be switched between: • ARM state and THUMB state using the BX and BLX instructions, and loads to the PC • ARM state and Jazelle state using the BXJ instruction All exceptions are entered, handled and exited in ARM state. If an exception occurs in Thumb or Jazelle states, the processor reverts to ARM state. The transition back to Thumb or Jazelle states occurs automatically on return from the exception handler. 11.3.3 Instruction Pipelines The ARM9EJ-S core uses two kinds of pipelines to increase the speed of the flow of instructions to the processor. A five-stage (five clock cycles) pipeline is used for ARM and Thumb states. It consists of Fetch, Decode, Execute, Memory and Writeback stages. A six-stage (six clock cycles) pipeline is used for Jazelle state It consists of Fetch, Jazelle/Decode (two clock cycles), Execute, Memory and Writeback stages. 11.3.4 Memory Access The ARM9EJ-S core supports byte (8-bit), half-word (16-bit) and word (32-bit) access. Words must be aligned to four-byte boundaries, half-words must be aligned to two-byte boundaries and bytes can be placed on any byte boundary. Because of the nature of the pipelines, it is possible for a value to be required for use before it has been placed in the register bank by the actions of an earlier instruction. The ARM9EJ-S control logic automatically detects these cases and stalls the core or forward data. 11.3.5 Jazelle Technology The Jazelle technology enables direct and efficient execution of Java byte codes on ARM processors, providing high performance for the next generation of Java-powered wireless and embedded devices. The new Java feature of ARM9EJ-S can be described as a hardware emulation of a JVM (Java Virtual Machine). Java mode will appear as another state: instead of executing ARM or Thumb instructions, it executes Java byte codes. The Java byte code decoder logic implemented in ARM9EJ-S decodes 95% of executed byte codes and turns them into ARM instructions without any overhead, while less frequently used byte codes are broken down into optimized sequences of ARM instructions. The hardware/software split is invisible to the programmer, invisible to the application and invisible to the operating system. All existing ARM registers are re-used in Jazelle state and all registers then have particular functions in this mode. 41 6384D–ATARM–04-May-09 Minimum interrupt latency is maintained across both ARM state and Java state. Since byte codes execution can be restarted, an interrupt automatically triggers the core to switch from Java state to ARM state for the execution of the interrupt handler. This means that no special provision has to be made for handling interrupts while executing byte codes, whether in hardware or in software. 11.3.6 ARM9EJ-S Operating Modes In all states, there are seven operation modes: • User mode is the usual ARM program execution state. It is used for executing most application programs • Fast Interrupt (FIQ) mode is used for handling fast interrupts. It is suitable for high-speed data transfer or channel process • Interrupt (IRQ) mode is used for general-purpose interrupt handling • Supervisor mode is a protected mode for the operating system • Abort mode is entered after a data or instruction prefetch abort • System mode is a privileged user mode for the operating system • Undefined mode is entered when an undefined instruction exception occurs Mode changes may be made under software control, or may be brought about by external interrupts or exception processing. Most application programs execute in User Mode. The non-user modes, known as privileged modes, are entered in order to service interrupts or exceptions or to access protected resources. 11.3.7 ARM9EJ-S Registers The ARM9EJ-S core has a total of 37 registers. • 31 general-purpose 32-bit registers • 6 32-bit status registers Table 11-1 shows all the registers in all modes. Table 11-1. User and System Mode R0 R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 R11 ARM9TDMI Modes and Registers Layout Supervisor Mode R0 R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 R11 Abort Mode R0 R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 R11 Undefined Mode R0 R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 R11 Interrupt Mode R0 R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 R11 Fast Interrupt Mode R0 R1 R2 R3 R4 R5 R6 R7 R8_FIQ R9_FIQ R10_FIQ R11_FIQ 42 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Table 11-1. User and System Mode R12 R13 R14 PC ARM9TDMI Modes and Registers Layout (Continued) Supervisor Mode R12 R13_SVC R14_SVC PC Abort Mode R12 R13_ABORT R14_ABORT PC Undefined Mode R12 R13_UNDEF R14_UNDEF PC Interrupt Mode R12 R13_IRQ R14_IRQ PC Fast Interrupt Mode R12_FIQ R13_FIQ R14_FIQ PC CPSR CPSR SPSR_SVC CPSR SPSR_ABOR T CPSR SPSR_UNDE F CPSR SPSR_IRQ CPSR SPSR_FIQ Mode-specific banked registers The ARM state register set contains 16 directly-accessible registers, r0 to r15, and an additional register, the Current Program Status Register (CPSR). Registers r0 to r13 are general-purpose registers used to hold either data or address values. Register r14 is used as a Link register that holds a value (return address) of r15 when BL or BLX is executed. Register r15 is used as a program counter (PC), whereas the Current Program Status Register (CPSR) contains condition code flags and the current mode bits. In privileged modes (FIQ, Supervisor, Abort, IRQ, Undefined), mode-specific banked registers (r8 to r14 in FIQ mode or r13 to r14 in the other modes) become available. The corresponding banked registers r14_fiq, r14_svc, r14_abt, r14_irq, r14_und are similarly used to hold the values (return address for each mode) of r15 (PC) when interrupts and exceptions arise, or when BL or BLX instructions are executed within interrupt or exception routines. There is another register called Saved Program Status Register (SPSR) that becomes available in privileged modes instead of CPSR. This register contains condition code flags and the current mode bits saved as a result of the exception that caused entry to the current (privileged) mode. In all modes and due to a software agreement, register r13 is used as stack pointer. The use and the function of all the registers described above should obey ARM Procedure Call Standard (APCS) which defines: • constraints on the use of registers • stack conventions • argument passing and result return For more details, refer to ARM Software Development Kit. The Thumb state register set is a subset of the ARM state set. The programmer has direct access to: • Eight general-purpose registers r0-r7 • Stack pointer, SP • Link register, LR (ARM r14) • PC • CPSR 43 6384D–ATARM–04-May-09 There are banked registers SPs, LRs and SPSRs for each privileged mode (for more details see the ARM9EJ-S Technical Reference Manual, revision r1p2 page 2-12). 11.3.7.1 Status Registers The ARM9EJ-S core contains one CPSR, and five SPSRs for exception handlers to use. The program status registers: • hold information about the most recently performed ALU operation • control the enabling and disabling of interrupts • set the processor operation mode Figure 11-2. Status Register Format 31 30 29 28 27 24 765 0 NZCVQ J Reserved I FT Mode Jazelle state bit Reserved Sticky Overflow Overflow Carry/Borrow/Extend Zero Negative/Less than Mode bits Thumb state bit FIQ disable IRQ disable Figure 11-2 shows the status register format, where: • N: Negative, Z: Zero, C: Carry, and V: Overflow are the four ALU flags • The Sticky Overflow (Q) flag can be set by certain multiply and fractional arithmetic instructions like QADD, QDADD, QSUB, QDSUB, SMLAxy, and SMLAWy needed to achieve DSP operations. The Q flag is sticky in that, when set by an instruction, it remains set until explicitly cleared by an MSR instruction writing to the CPSR. Instructions cannot execute conditionally on the status of the Q flag. • The J bit in the CPSR indicates when the ARM9EJ-S core is in Jazelle state, where: – J = 0: The processor is in ARM or Thumb state, depending on the T bit – J = 1: The processor is in Jazelle state. • Mode: five bits to encode the current processor mode 11.3.7.2 Exceptions Exception Types and Priorities The ARM9EJ-S supports five types of exceptions. Each type drives the ARM9EJ-S in a privi- leged mode. The types of exceptions are: • Fast interrupt (FIQ) • Normal interrupt (IRQ) • Data and Prefetched aborts (Abort) • Undefined instruction (Undefined) • Software interrupt and Reset (Supervisor) 44 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary When an exception occurs, the banked version of R14 and the SPSR for the exception mode are used to save the state. More than one exception can happen at a time, therefore the ARM9EJ-S takes the arisen exceptions according to the following priority order: • Reset (highest priority) • Data Abort • FIQ • IRQ • Prefetch Abort • BKPT, Undefined instruction, and Software Interrupt (SWI) (Lowest priority) The BKPT, or Undefined instruction, and SWI exceptions are mutually exclusive. Note that there is one exception in the priority scheme: when FIQs are enabled and a Data Abort occurs at the same time as an FIQ, the ARM9EJ-S core enters the Data Abort handler, and proceeds immediately to FIQ vector. A normal return from the FIQ causes the Data Abort handler to resume execution. Data Aborts must have higher priority than FIQs to ensure that the transfer error does not escape detection. Exception Modes and Handling Exceptions arise whenever the normal flow of a program must be halted temporarily, for example, to service an interrupt from a peripheral. When handling an ARM exception, the ARM9EJ-S core performs the following operations: 1. Preserves the address of the next instruction in the appropriate Link Register that corresponds to the new mode that has been entered. When the exception entry is from: – ARM and Jazelle states, the ARM9EJ-S copies the address of the next instruction into LR (current PC(r15) + 4 or PC + 8 depending on the exception). – THUMB state, the ARM9EJ-S writes the value of the PC into LR, offset by a value (current PC + 2, PC + 4 or PC + 8 depending on the exception) that causes the program to resume from the correct place on return. 2. Copies the CPSR into the appropriate SPSR. 3. Forces the CPSR mode bits to a value that depends on the exception. 4. Forces the PC to fetch the next instruction from the relevant exception vector. The register r13 is also banked across exception modes to provide each exception handler with private stack pointer. The ARM9EJ-S can also set the interrupt disable flags to prevent otherwise unmanageable nesting of exceptions. When an exception has completed, the exception handler must move both the return value in the banked LR minus an offset to the PC and the SPSR to the CPSR. The offset value varies according to the type of exception. This action restores both PC and the CPSR. The fast interrupt mode has seven private registers r8 to r14 (banked registers) to reduce or remove the requirement for register saving which minimizes the overhead of context switching. The Prefetch Abort is one of the aborts that indicates that the current memory access cannot be completed. When a Prefetch Abort occurs, the ARM9EJ-S marks the prefetched instruction as invalid, but does not take the exception until the instruction reaches the Execute stage in the 45 6384D–ATARM–04-May-09 pipeline. If the instruction is not executed, for example because a branch occurs while it is in the pipeline, the abort does not take place. The breakpoint (BKPT) instruction is a new feature of ARM9EJ-S that is destined to solve the problem of the Prefetch Abort. A breakpoint instruction operates as though the instruction caused a Prefetch Abort. A breakpoint instruction does not cause the ARM9EJ-S to take the Prefetch Abort exception until the instruction reaches the Execute stage of the pipeline. If the instruction is not executed, for example because a branch occurs while it is in the pipeline, the breakpoint does not take place. 11.3.8 ARM Instruction Set Overview The ARM instruction set is divided into: • Branch instructions • Data processing instructions • Status register transfer instructions • Load and Store instructions • Coprocessor instructions • Exception-generating instructions ARM instructions can be executed conditionally. Every instruction contains a 4-bit condition code field (bits[31:28]). For further details, see the ARM Technical Reference Manual, ARM ref. DDI0198B. Table 11-2 gives the ARM instruction mnemonic list. Table 11-2. Mnemonic MOV ADD SUB RSB CMP TST AND EOR MUL SMULL SMLAL MSR B BX LDR LDRSH LDRSB ARM Instruction Mnemonic List Operation Move Add Subtract Reverse Subtract Compare Test Logical AND Logical Exclusive OR Multiply Sign Long Multiply Signed Long Multiply Accumulate Move to Status Register Branch Branch and Exchange Load Word Load Signed Halfword Load Signed Byte Mnemonic MVN ADC SBC RSC CMN TEQ BIC ORR MLA UMULL UMLAL MRS BL SWI STR Operation Move Not Add with Carry Subtract with Carry Reverse Subtract with Carry Compare Negated Test Equivalence Bit Clear Logical (inclusive) OR Multiply Accumulate Unsigned Long Multiply Unsigned Long Multiply Accumulate Move From Status Register Branch and Link Software Interrupt Store Word 46 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Table 11-2. Mnemonic LDRH LDRB LDRBT LDRT LDM SWP MCR LDC CDP ARM Instruction Mnemonic List (Continued) Operation Load Half Word Load Byte Load Register Byte with Translation Load Register with Translation Load Multiple Swap Word Move To Coprocessor Load To Coprocessor Coprocessor Data Processing Mnemonic STRH STRB STRBT STRT STM SWPB MRC STC Operation Store Half Word Store Byte Store Register Byte with Translation Store Register with Translation Store Multiple Swap Byte Move From Coprocessor Store From Coprocessor 11.3.9 New ARM Instruction Set . Table 11-3. Mnemonic BXJ BLX (1) SMLAxy SMLAL SMLAWy SMULxy SMULWy QADD QDADD QSUB QDSUB New ARM Instruction Mnemonic List Operation Branch and exchange to Java Branch, Link and exchange Signed Multiply Accumulate 16 * 16 bit Signed Multiply Accumulate Long Signed Multiply Accumulate 32 * 16 bit Signed Multiply 16 * 16 bit Signed Multiply 32 * 16 bit Saturated Add Saturated Add with Double Saturated subtract Saturated Subtract with double Mnemonic MRRC MCR2 MCRR CDP2 BKPT PLD STRD STC2 LDRD LDC2 CLZ Operation Move double from coprocessor Alternative move of ARM reg to coprocessor Move double to coprocessor Alternative Coprocessor Data Processing Breakpoint Soft Preload, Memory prepare to load from address Store Double Alternative Store from Coprocessor Load Double Alternative Load to Coprocessor Count Leading Zeroes Note: 1. A Thumb BLX contains two consecutive Thumb instructions, and takes four cycles. 11.3.10 Thumb Instruction Set Overview The Thumb instruction set is a re-encoded subset of the ARM instruction set. The Thumb instruction set is divided into: • Branch instructions • Data processing instructions • Load and Store instructions • Load and Store multiple instructions 47 6384D–ATARM–04-May-09 • Exception-generating instruction Table 5 shows the Thumb instruction set, for further details, see the ARM Technical Reference Manual, ARM ref. DDI0198B. Table 11-4 gives the Thumb instruction mnemonic list. Table 11-4. Mnemonic MOV ADD SUB CMP TST AND EOR LSL ASR MUL B BX LDR LDRH LDRB LDRSH LDMIA PUSH BCC Thumb Instruction Mnemonic List Operation Move Add Subtract Compare Test Logical AND Logical Exclusive OR Logical Shift Left Arithmetic Shift Right Multiply Branch Branch and Exchange Load Word Load Half Word Load Byte Load Signed Halfword Load Multiple Push Register to stack Conditional Branch Mnemonic MVN ADC SBC CMN NEG BIC ORR LSR ROR BLX BL SWI STR STRH STRB LDRSB STMIA POP BKPT Operation Move Not Add with Carry Subtract with Carry Compare Negated Negate Bit Clear Logical (inclusive) OR Logical Shift Right Rotate Right Branch, Link, and Exchange Branch and Link Software Interrupt Store Word Store Half Word Store Byte Load Signed Byte Store Multiple Pop Register from stack Breakpoint 48 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 11.4 CP15 Coprocessor Coprocessor 15, or System Control Coprocessor CP15, is used to configure and control all the items in the list below: • ARM9EJ-S • Caches (ICache, DCache and write buffer) • TCM • MMU • Other system options To control these features, CP15 provides 16 additional registers. See Table 11-5. Table 11-5. Register 0 0 0 1 2 3 4 5 5 6 7 8 9 9 10 11 12 13 13 14 15 Notes: CP15 Registers Name ID Code (1) (1) Read/Write Read/Unpredictable Read/Unpredictable Read/Unpredictable Read/write Read/write Read/write None (1) (1) Cache type TCM status(1) Control Translation Table Base Domain Access Control Reserved Data fault Status Read/write Read/write Read/write Read/Write Unpredictable/Write Instruction fault status Fault Address Cache Operations TLB operations cache lockdown TCM region TLB lockdown Reserved Reserved FCSE PID (1) (2) Read/write Read/write Read/write None None Read/write Read/Write None Read/Write Context ID(1) Reserved Test configuration 1. Register locations 0,5, and 13 each provide access to more than one register. The register accessed depends on the value of the opcode_2 field. 2. Register location 9 provides access to more than one register. The register accessed depends on the value of the CRm field. 49 6384D–ATARM–04-May-09 11.4.1 CP15 Registers Access CP15 registers can only be accessed in privileged mode by: • MCR (Move to Coprocessor from ARM Register) instruction is used to write an ARM register to CP15. • MRC (Move to ARM Register from Coprocessor) instruction is used to read the value of CP15 to an ARM register. Other instructions like CDP, LDC, STC can cause an undefined instruction exception. The assembler code for these instructions is: MCR/MRC{cond} p15, opcode_1, Rd, CRn, CRm, opcode_2. The MCR, MRC instructions bit pattern is shown below: 31 30 29 28 27 26 25 24 cond 23 22 21 20 1 19 1 18 1 17 0 16 opcode_1 15 14 13 L 12 11 10 CRn 9 8 Rd 7 6 5 4 1 3 1 2 1 1 1 0 opcode_2 1 CRm • CRm[3:0]: Specified Coprocessor Action Determines specific coprocessor action. Its value is dependent on the CP15 register used. For details, refer to CP15 specific register behavior. • opcode_2[7:5] Determines specific coprocessor operation code. By default, set to 0. • Rd[15:12]: ARM Register Defines the ARM register whose value is transferred to the coprocessor. If R15 is chosen, the result is unpredictable. • CRn[19:16]: Coprocessor Register Determines the destination coprocessor register. • L: Instruction Bit 0 = MCR instruction 1 = MRC instruction • opcode_1[23:20]: Coprocessor Code Defines the coprocessor specific code. Value is c15 for CP15. • cond [31:28]: Condition For more details, see Chapter 2 in ARM926EJ-S TRM. 50 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 11.5 Memory Management Unit (MMU) The ARM926EJ-S processor implements an enhanced ARM architecture v5 MMU to provide virtual memory features required by operating systems like Symbian OS®, Windows CE, and Linux. These virtual memory features are memory access permission controls and virtual to physical address translations. The Virtual Address generated by the CPU core is converted to a Modified Virtual Address (MVA) by the FCSE (Fast Context Switch Extension) using the value in CP15 register13. The MMU translates modified virtual addresses to physical addresses by using a single, two-level page table set stored in physical memory. Each entry in the set contains the access permissions and the physical address that correspond to the virtual address. The first level translation tables contain 4096 entries indexed by bits [31:20] of the MVA. These entries contain a pointer to either a 1 MB section of physical memory along with attribute information (access permissions, domain, etc.) or an entry in the second level translation tables; coarse table and fine table. The second level translation tables contain two subtables, coarse table and fine table. An entry in the coarse table contains a pointer to both large pages and small pages along with access permissions. An entry in the fine table contains a pointer to large, small and tiny pages. Table 7 shows the different attributes of each page in the physical memory. Table 11-6. Mapping Details Mapping Size 1M byte 64K bytes 4K bytes 1K byte Access Permission By Section 4 separated subpages 4 separated subpages Tiny Page Subpage Size 16K bytes 1K byte - Mapping Name Section Large Page Small Page Tiny Page The MMU consists of: • Access control logic • Translation Look-aside Buffer (TLB) • Translation table walk hardware 11.5.1 Access Control Logic The access control logic controls access information for every entry in the translation table. The access control logic checks two pieces of access information: domain and access permissions. The domain is the primary access control mechanism for a memory region; there are 16 of them. It defines the conditions necessary for an access to proceed. The domain determines whether the access permissions are used to qualify the access or whether they should be ignored. The second access control mechanism is access permissions that are defined for sections and for large, small and tiny pages. Sections and tiny pages have a single set of access permissions whereas large and small pages can be associated with 4 sets of access permissions, one for each subpage (quarter of a page). 11.5.2 Translation Look-aside Buffer (TLB) The Translation Look-aside Buffer (TLB) caches translated entries and thus avoids going through the translation process every time. When the TLB contains an entry for the MVA (Modi- 51 6384D–ATARM–04-May-09 fied Virtual Address), the access control logic determines if the access is permitted and outputs the appropriate physical address corresponding to the MVA. If access is not permitted, the MMU signals the CPU core to abort. If the TLB does not contain an entry for the MVA, the translation table walk hardware is invoked to retrieve the translation information from the translation table in physical memory. 11.5.3 Translation Table Walk Hardware The translation table walk hardware is a logic that traverses the translation tables located in physical memory, gets the physical address and access permissions and updates the TLB. The number of stages in the hardware table walking is one or two depending whether the address is marked as a section-mapped access or a page-mapped access. There are three sizes of page-mapped accesses and one size of section-mapped access. Pagemapped accesses are for large pages, small pages and tiny pages. The translation process always begins with a level one fetch. A section-mapped access requires only a level one fetch, but a page-mapped access requires an additional level two fetch. For further details on the MMU, please refer to chapter 3 in ARM926EJ-S Technical Reference Manual. 11.5.4 MMU Faults The MMU generates an abort on the following types of faults: • Alignment faults (for data accesses only) • Translation faults • Domain faults • Permission faults The access control mechanism of the MMU detects the conditions that produce these faults. If the fault is a result of memory access, the MMU aborts the access and signals the fault to the CPU core.The MMU retains status and address information about faults generated by the data accesses in the data fault status register and fault address register. It also retains the status of faults generated by instruction fetches in the instruction fault status register. The fault status register (register 5 in CP15) indicates the cause of a data or prefetch abort, and the domain number of the aborted access when it happens. The fault address register (register 6 in CP15) holds the MVA associated with the access that caused the Data Abort. For further details on MMU faults, please refer to chapter 3 in ARM926EJ-S Technical Reference Manual. 52 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 11.6 Caches and Write Buffer The ARM926EJ-S contains a 32 KB Instruction Cache (ICache), a 32 KB Data Cache (DCache), and a write buffer. Although the ICache and DCache share common features, each still has some specific mechanisms. The caches (ICache and DCache) are four-way set associative, addressed, indexed and tagged using the Modified Virtual Address (MVA), with a cache line length of eight words with two dirty bits for the DCache. The ICache and DCache provide mechanisms for cache lockdown, cache pollution control, and line replacement. A new feature is now supported by ARM926EJ-S caches called allocate on read-miss commonly known as wrapping. This feature enables the caches to perform critical word first cache refilling. This means that when a request for a word causes a read-miss, the cache performs an AHB access. Instead of loading the whole line (eight words), the cache loads the critical word first, so the processor can reach it quickly, and then the remaining words, no matter where the word is located in the line. The caches and the write buffer are controlled by the CP15 register 1 (Control), CP15 register 7 (cache operations) and CP15 register 9 (cache lockdown). 11.6.1 Instruction Cache (ICache) The ICache caches fetched instructions to be executed by the processor. The ICache can be enabled by writing 1 to I bit of the CP15 Register 1 and disabled by writing 0 to this same bit. When the MMU is enabled, all instruction fetches are subject to translation and permission checks. If the MMU is disabled, all instructions fetches are cachable, no protection checks are made and the physical address is flat-mapped to the modified virtual address. With the MVA use disabled, context switching incurs ICache cleaning and/or invalidating. When the ICache is disabled, all instruction fetches appear on external memory (AHB) (see Tables 4-1 and 4-2 in page 4-4 in ARM926EJ-S TRM). On reset, the ICache entries are invalidated and the ICache is disabled. For best performance, ICache should be enabled as soon as possible after reset. 11.6.2 Data Cache (DCache) and Write Buffer ARM926EJ-S includes a DCache and a write buffer to reduce the effect of main memory bandwidth and latency on data access performance. The operations of DCache and write buffer are closely connected. DCache The DCache needs the MMU to be enabled. All data accesses are subject to MMU permission and translation checks. Data accesses that are aborted by the MMU do not cause linefills or data accesses to appear on the AMBA ASB interface. If the MMU is disabled, all data accesses are noncachable, nonbufferable, with no protection checks, and appear on the AHB bus. All addresses are flat-mapped, VA = MVA = PA, which incurs DCache cleaning and/or invalidating every time a context switch occurs. The DCache stores the Physical Address Tag (PA Tag) from which every line was loaded and uses it when writing modified lines back to external memory. This means that the MMU is not involved in write-back operations. Each line (8 words) in the DCache has two dirty bits, one for the first four words and the other one for the second four words. These bits, if set, mark the associated half-lines as dirty. If the 53 6384D–ATARM–04-May-09 11.6.2.1 cache line is replaced due to a linefill or a cache clean operation, the dirty bits are used to decide whether all, half or none is written back to memory. DCache can be enabled or disabled by writing either 1 or 0 to bit C in register 1 of CP15 (see Tables 4-3 and 4-4 on page 4-5 in ARM926EJ-S TRM). The DCache supports write-through and write-back cache operations, selected by memory region using the C and B bits in the MMU translation tables. The DCache contains an eight data word entry, single address entry write-back buffer used to hold write-back data for cache line eviction or cleaning of dirty cache lines. The Write Buffer can hold up to 16 words of data and four separate addresses. DCache and Write Buffer operations are closely connected as their configuration is set in each section by the page descriptor in the MMU translation table. 11.6.2.2 Write Buffer The ARM926EJ-S contains a write buffer that has a 16-word data buffer and a four- address buffer. The write buffer is used for all writes to a bufferable region, write-through region and write-back region. It also allows to avoid stalling the processor when writes to external memory are performed. When a store occurs, data is written to the write buffer at core speed (high speed). The write buffer then completes the store to external memory at bus speed (typically slower than the core speed). During this time, the ARM9EJ-S processor can preform other tasks. DCache and Write Buffer support write-back and write-through memory regions, controlled by C and B bits in each section and page descriptor within the MMU translation tables. 11.6.2.3 Write-though Operation When a cache write hit occurs, the DCache line is updated. The updated data is then written to the write buffer which transfers it to external memory. When a cache write miss occurs, a line, chosen by round robin or another algorithm, is stored in the write buffer which transfers it to external memory. 11.6.2.4 Write-back Operation When a cache write hit occurs, the cache line or half line is marked as dirty, meaning that its contents are not up-to-date with those in the external memory. When a cache write miss occurs, a line, chosen by round robin or another algorithm, is stored in the write buffer which transfers it to external memory. 54 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 11.7 Bus Interface Unit The ARM926EJ-S features a Bus Interface Unit (BIU) that arbitrates and schedules AHB requests. The BIU implements a multi-layer AHB, based on the AHB-Lite protocol, that enables parallel access paths between multiple AHB masters and slaves in a system. This is achieved by using a more complex interconnection matrix and gives the benefit of increased overall bus bandwidth, and a more flexible system architecture. The multi-master bus architecture has a number of benefits: • It allows the development of multi-master systems with an increased bus bandwidth and a flexible architecture. • Each AHB layer becomes simple because it only has one master, so no arbitration or masterto-slave muxing is required. AHB layers, implementing AHB-Lite protocol, do not have to support request and grant, nor do they have to support retry and split transactions. • The arbitration becomes effective when more than one master wants to access the same slave simultaneously. 11.7.1 Supported Transfers The ARM926EJ-S processor performs all AHB accesses as single word, bursts of four words, or bursts of eight words. Any ARM9EJ-S core request that is not 1, 4, 8 words in size is split into packets of these sizes. Note that the Atmel bus is AHB-Lite protocol compliant, hence it does not support split and retry requests. Table 8 gives an overview of the supported transfers and different kinds of transactions they are used for. Table 11-7. HBurst[2:0] Supported Transfers Description Single transfer of word, half word, or byte: • data write (NCNB, NCB, WT, or WB that has missed in DCache) SINGLE Single transfer • data read (NCNB or NCB) • NC instruction fetch (prefetched and non-prefetched) • page table walk read Half-line cache write-back, Instruction prefetch, if enabled. Four-word burst NCNB, NCB, WT, or WB write. Full-line cache write-back, eight-word burst NCNB, NCB, WT, or WB write. Cache linefill INCR4 INCR8 WRAP8 Four-word incrementing burst Eight-word incrementing burst Eight-word wrapping burst 11.7.2 Thumb Instruction Fetches All instructions fetches, regardless of the state of ARM9EJ-S core, are made as 32-bit accesses on the AHB. If the ARM9EJ-S is in Thumb state, then two instructions can be fetched at a time. Address Alignment The ARM926EJ-S BIU performs address alignment checking and aligns AHB addresses to the necessary boundary. 16-bit accesses are aligned to halfword boundaries, and 32-bit accesses are aligned to word boundaries. 11.7.3 55 6384D–ATARM–04-May-09 56 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 12. AT91SAM9G20 Debug and Test 12.1 Overview The AT91SAM9G20 features a number of complementary debug and test capabilities. A common JTAG/ICE (In-Circuit Emulator) port is used for standard debugging functions, such as downloading code and single-stepping through programs. The Debug Unit provides a two-pin UART that can be used to upload an application into internal SRAM. It manages the interrupt handling of the internal COMMTX and COMMRX signals that trace the activity of the Debug Communication Channel. A set of dedicated debug and test input/output pins gives direct access to these capabilities from a PC-based test environment. 57 6384D–ATARM–04-May-09 12.2 Block Diagram Figure 12-1. Debug and Test Block Diagram TMS TCK TDI NTRST Boundary Port ICE/JTAG TAP JTAGSEL TDO RTCK Reset and Test POR TST ARM9EJ-S ICE-RT ARM926EJ-S PDC DBGU PIO DTXD DRXD TAP: Test Access Port 58 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 12.3 12.3.1 Application Examples Debug Environment Figure 12-2 on page 59 shows a complete debug environment example. The ICE/JTAG interface is used for standard debugging functions, such as downloading code and single-stepping through the program. A software debugger running on a personal computer provides the user interface for configuring a Trace Port interface utilizing the ICE/JTAG interface. Figure 12-2. Application Debug and Trace Environment Example Host Debugger ICE/JTA ICE/JTAG AT91SAM9G20 RS232 Connector Terminal AT91SAM9G20-based Application 59 6384D–ATARM–04-May-09 12.3.2 Test Environment Figure 12-3 on page 60 shows a test environment example. Test vectors are sent and interpreted by the tester. In this example, the “board in test” is designed using a number of JTAGcompliant devices. These devices can be connected to form a single scan chain. Figure 12-3. Application Test Environment Example Test Adaptor Tester JTAG Interface ICE/JTAG Connector Chip n Chip 2 AT91SAM9G20 Chip 1 AT91SAM9G20-based Application Board In Test 12.4 Debug and Test Pin Description Table 12-1. Pin Name Debug and Test Pin List Function Reset/Test Type Active Level NRST TST Microcontroller Reset Test Mode Select ICE and JTAG Input/Output Input Low High NTRST TCK TDI TDO TMS RTCK JTAGSEL Test Reset Signal Test Clock Test Data In Test Data Out Test Mode Select Returned Test Clock JTAG Selection Debug Unit Input Input Input Output Input Output Input Low DRXD DTXD Debug Receive Data Debug Transmit Data Input Output 60 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 12.5 12.5.1 Functional Description Test Pin One dedicated pin, TST, is used to define the device operating mode. The user must make sure that this pin is tied at low level to ensure normal operating conditions. Other values associated with this pin are reserved for manufacturing test. 12.5.2 EmbeddedICE The ARM9EJ-S EmbeddedICE-RT™ is supported via the ICE/JTAG port. It is connected to a host computer via an ICE interface. Debug support is implemented using an ARM9EJ-S core embedded within the ARM926EJ-S. The internal state of the ARM926EJ-S is examined through an ICE/JTAG port which allows instructions to be serially inserted into the pipeline of the core without using the external data bus. Therefore, when in debug state, a store-multiple (STM) can be inserted into the instruction pipeline. This exports the contents of the ARM9EJ-S registers. This data can be serially shifted out without affecting the rest of the system. There are two scan chains inside the ARM9EJ-S processor which support testing, debugging, and programming of the EmbeddedICE-RT. The scan chains are controlled by the ICE/JTAG port. EmbeddedICE mode is selected when JTAGSEL is low. It is not possible to switch directly between ICE and JTAG operations. A chip reset must be performed after JTAGSEL is changed. For further details on the EmbeddedICE-RT, see the ARM document: ARM9EJ-S Technical Reference Manual (DDI 0222A). 12.5.3 JTAG Signal Description TMS is the Test Mode Select input which controls the transitions of the test interface state machine. TDI is the Test Data Input line which supplies the data to the JTAG registers (Boundary Scan Register, Instruction Register, or other data registers). TDO is the Test Data Output line which is used to serially output the data from the JTAG registers to the equipment controlling the test. It carries the sampled values from the boundary scan chain (or other JTAG registers) and propagates them to the next chip in the serial test circuit. NTRST (optional in IEEE Standard 1149.1) is a Test-ReSeT input which is mandatory in ARM cores and used to reset the debug logic. On Atmel ARM926EJ-S-based cores, NTRST is a Power On Reset output. It is asserted on power on. If necessary, the user can also reset the debug logic with the NTRST pin assertion during 2.5 MCK periods. TCK is the Test ClocK input which enables the test interface. TCK is pulsed by the equipment controlling the test and not by the tested device. It can be pulsed at any frequency. Note the maximum JTAG clock rate on ARM926EJ-S cores is 1/6th the clock of the CPU. This gives 5.45 kHz maximum initial JTAG clock rate for an ARM9E™ running from the 32.768 kHz slow clock. RTCK is the Return Test Clock. Not an IEEE Standard 1149.1 signal added for a better clock handling by emulators. From some ICE Interface probes, this return signal can be used to synchronize the TCK clock and take not care about the given ratio between the ICE Interface clock and system clock equal to 1/6th. This signal is only available in JTAG ICE Mode and not in boundary scan mode. 61 6384D–ATARM–04-May-09 12.5.4 Debug Unit The Debug Unit provides a two-pin (DXRD and TXRD) USART that can be used for several debug and trace purposes and offers an ideal means for in-situ programming solutions and debug monitor communication. Moreover, the association with two peripheral data controller channels permits packet handling of these tasks with processor time reduced to a minimum. The Debug Unit also manages the interrupt handling of the COMMTX and COMMRX signals that come from the ICE and that trace the activity of the Debug Communication Channel.The Debug Unit allows blockage of access to the system through the ICE interface. A specific register, the Debug Unit Chip ID Register, gives information about the product version and its internal configuration. The AT91SAM9G20 Debug Unit Chip ID value is 0x0199 05A1 on 32-bit width. For further details on the Debug Unit, see the Debug Unit section. 12.5.5 IEEE 1149.1 JTAG Boundary Scan IEEE 1149.1 JTAG Boundary Scan allows pin-level access independent of the device packaging technology. IEEE 1149.1 JTAG Boundary Scan is enabled when JTAGSEL is high. The SAMPLE, EXTEST and BYPASS functions are implemented. In ICE debug mode, the ARM processor responds with a non-JTAG chip ID that identifies the processor to the ICE system. This is not IEEE 1149.1 JTAG-compliant. It is not possible to switch directly between JTAG and ICE operations. A chip reset must be performed after JTAGSEL is changed. A Boundary-scan Descriptor Language (BSDL) file is provided to set up test. 12.5.5.1 JTAG Boundary-scan Register The Boundary-scan Register (BSR) contains 308 bits that correspond to active pins and associated control signals. Each AT91SAM9G20 input/output pin corresponds to a 3-bit register in the BSR. The OUTPUT bit contains data that can be forced on the pad. The INPUT bit facilitates the observability of data applied to the pad. The CONTROL bit selects the direction of the pad. Table 12-2. Bit Number 307 A0 306 305 A1 304 303 A10 302 301 A11 300 299 A12 298 IN/OUT INPUT/OUTPUT IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL AT91SAM9G20 JTAG Boundary Scan Register Pin Name Pin Type Associated BSR Cells CONTROL 62 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Table 12-2. 297 A13 296 295 A14 294 293 A15 292 291 A16 290 289 A17 288 287 A18 286 285 A19 284 283 A2 282 281 A20 280 279 A21 278 277 A22 276 275 A3 274 273 A4 272 271 A5 270 269 A6 268 267 A7 266 265 A8 264 263 A9 262 261 BMS INPUT IN/OUT INPUT/OUTPUT INPUT IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL AT91SAM9G20 JTAG Boundary Scan Register CONTROL 63 6384D–ATARM–04-May-09 Table 12-2. 260 AT91SAM9G20 JTAG Boundary Scan Register CONTROL CAS IN/OUT INPUT/OUTPUT CONTROL D0 IN/OUT INPUT/OUTPUT CONTROL D1 IN/OUT INPUT/OUTPUT CONTROL D10 IN/OUT INPUT/OUTPUT CONTROL D11 IN/OUT INPUT/OUTPUT CONTROL D12 IN/OUT INPUT/OUTPUT CONTROL D13 IN/OUT INPUT/OUTPUT CONTROL D14 IN/OUT INPUT/OUTPUT CONTROL D15 IN/OUT INPUT/OUTPUT CONTROL D2 IN/OUT INPUT/OUTPUT CONTROL D3 IN/OUT INPUT/OUTPUT CONTROL D4 IN/OUT INPUT/OUTPUT CONTROL D5 IN/OUT INPUT/OUTPUT CONTROL D6 IN/OUT INPUT/OUTPUT CONTROL D7 IN/OUT INPUT/OUTPUT CONTROL D8 IN/OUT INPUT/OUTPUT CONTROL D9 IN/OUT INPUT/OUTPUT CONTROL NANDOE IN/OUT INPUT/OUTPUT 259 258 257 256 255 254 253 252 251 250 249 248 247 246 245 244 243 242 241 240 239 238 237 236 235 234 233 232 231 230 229 228 227 226 225 64 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Table 12-2. 224 NANDWE 223 222 NCS0 221 220 NCS1 219 218 NRD 217 216 NRST 215 214 NWR0 213 212 NWR1 211 210 NWR3 209 208 207 PA0 206 205 PA1 204 203 PA10 202 201 PA11 200 199 PA12 198 197 PA13 196 195 PA14 194 193 PA15 192 191 PA16 190 189 PA17 188 IN/OUT INPUT/OUTPUT IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL OSCSEL INPUT IN/OUT INPUT/OUTPUT INPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL AT91SAM9G20 JTAG Boundary Scan Register CONTROL 65 6384D–ATARM–04-May-09 Table 12-2. 187 AT91SAM9G20 JTAG Boundary Scan Register CONTROL PA18 IN/OUT INPUT/OUTPUT CONTROL PA19 IN/OUT INPUT/OUTPUT CONTROL PA2 IN/OUT INPUT/OUTPUT CONTROL PA20 IN/OUT INPUT/OUTPUT CONTROL PA21 IN/OUT INPUT/OUTPUT CONTROL PA22 IN/OUT INPUT/OUTPUT CONTROL PA23 IN/OUT INPUT/OUTPUT CONTROL PA24 IN/OUT INPUT/OUTPUT CONTROL PA25 IN/OUT INPUT/OUTPUT CONTROL PA26 IN/OUT INPUT/OUTPUT CONTROL PA27 IN/OUT INPUT/OUTPUT CONTROL PA28 IN/OUT INPUT/OUTPUT CONTROL PA29 IN/OUT INPUT/OUTPUT CONTROL PA3 IN/OUT INPUT/OUTPUT internal internal internal internal CONTROL PA4 IN/OUT INPUT/OUTPUT CONTROL PA5 IN/OUT INPUT/OUTPUT 186 185 184 183 182 181 180 179 178 177 176 175 174 173 172 171 170 169 168 167 166 165 164 163 162 161 160 159 158 157 156 155 154 153 152 66 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Table 12-2. 151 PA6 150 149 PA7 148 147 PA8 146 145 PA9 144 143 PB0 142 141 PB1 140 139 PB10 138 137 PB11 136 135 134 133 132 131 PB14 130 129 PB15 128 127 PB16 126 125 PB17 124 123 PB18 122 121 PB19 120 119 PB2 118 117 PB20 116 IN/OUT INPUT/OUTPUT IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL internal internal internal internal CONTROL IN/OUT INPUT/OUTPUT IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL AT91SAM9G20 JTAG Boundary Scan Register CONTROL 67 6384D–ATARM–04-May-09 Table 12-2. 115 AT91SAM9G20 JTAG Boundary Scan Register CONTROL PB21 IN/OUT INPUT/OUTPUT CONTROL PB22 IN/OUT INPUT/OUTPUT CONTROL PB23 IN/OUT INPUT/OUTPUT CONTROL PB24 IN/OUT INPUT/OUTPUT CONTROL PB25 IN/OUT INPUT/OUTPUT CONTROL PB26 IN/OUT INPUT/OUTPUT CONTROL PB27 IN/OUT INPUT/OUTPUT CONTROL PB28 IN/OUT INPUT/OUTPUT CONTROL PB29 IN/OUT INPUT/OUTPUT CONTROL PB3 IN/OUT INPUT/OUTPUT CONTROL PB30 IN/OUT INPUT/OUTPUT CONTROL PB31 IN/OUT INPUT/OUTPUT CONTROL PB4 IN/OUT INPUT/OUTPUT CONTROL PB5 IN/OUT INPUT/OUTPUT CONTROL PB6 IN/OUT INPUT/OUTPUT CONTROL PB7 IN/OUT INPUT/OUTPUT CONTROL PB8 IN/OUT INPUT/OUTPUT CONTROL PB9 IN/OUT INPUT/OUTPUT 114 113 112 111 110 109 108 107 106 105 104 103 102 101 100 99 98 97 96 95 94 93 92 91 90 89 88 87 86 85 84 83 82 81 80 68 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Table 12-2. 79 PC0 78 77 PC1 76 75 PC10 74 73 PC11 72 71 70 69 PC13 68 67 PC14 66 65 PC15 64 63 PC16 62 61 PC17 60 59 PC18 58 57 PC19 56 55 54 53 PC20 52 51 PC21 50 49 PC22 48 47 PC23 46 45 PC24 44 IN/OUT INPUT/OUTPUT IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL internal internal CONTROL IN/OUT INPUT/OUTPUT IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL internal internal CONTROL IN/OUT INPUT/OUTPUT IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL AT91SAM9G20 JTAG Boundary Scan Register CONTROL 69 6384D–ATARM–04-May-09 Table 12-2. 43 AT91SAM9G20 JTAG Boundary Scan Register CONTROL PC25 IN/OUT INPUT/OUTPUT CONTROL PC26 IN/OUT INPUT/OUTPUT CONTROL PC27 IN/OUT INPUT/OUTPUT CONTROL PC28 IN/OUT INPUT/OUTPUT CONTROL PC29 IN/OUT INPUT/OUTPUT internal internal CONTROL PC30 IN/OUT INPUT/OUTPUT CONTROL PC31 IN/OUT INPUT/OUTPUT CONTROL PC4 IN/OUT INPUT/OUTPUT CONTROL PC5 IN/OUT INPUT/OUTPUT CONTROL PC6 IN/OUT INPUT/OUTPUT CONTROL PC7 IN/OUT INPUT/OUTPUT CONTROL PC8 IN/OUT INPUT/OUTPUT CONTROL PC9 IN/OUT INPUT/OUTPUT CONTROL RAS IN/OUT INPUT/OUTPUT CONTROL RTCK OUT OUTPUT CONTROL SDA10 IN/OUT INPUT/OUTPUT CONTROL SDCK IN/OUT INPUT/OUTPUT 42 41 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 09 08 70 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Table 12-2. 07 SDCKE 06 05 SDWE 04 03 SHDN 02 01 00 TST WKUP INPUT INPUT OUT OUTPUT INPUT INPUT IN/OUT INPUT/OUTPUT CONTROL IN/OUT INPUT/OUTPUT CONTROL AT91SAM9G20 JTAG Boundary Scan Register CONTROL 71 6384D–ATARM–04-May-09 12.5.6 JID Code Register Access: Read-only 31 30 29 28 27 26 25 24 VERSION 23 22 21 20 19 PART NUMBER 18 17 16 PART NUMBER 15 14 13 12 11 10 9 8 PART NUMBER 7 6 5 4 3 MANUFACTURER IDENTITY 2 1 0 MANUFACTURER IDENTITY 1 • VERSION[31:28]: Product Version Number Set to 0x0. • PART NUMBER[27:12]: Product Part Number Product part Number is 0x5B24 • MANUFACTURER IDENTITY[11:1] Set to 0x01F. Bit[0] required by IEEE Std. 1149.1. Set to 0x1. JTAG ID Code value is 0x05B2_403F. 72 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 13. AT91SAM9G20 Boot Program 13.1 Overview The Boot Program integrates different programs that manage download and/or upload into the different memories of the product. First, it initializes the Debug Unit serial port (DBGU) and the USB High Speed Device Port. The Boot program tries to detect SPI flash memories. The Serial Flash Boot program and DataFlash® B oot program are executed. It looks for a sequence of seven valid ARM exception vectors in a Serial Flash or DataFlash connected to the SPI. All these vectors must be B-branch or LDR load register instructions except for the sixth vector. This vector is used to store the size of the image to download. If a valid sequence is found, code is downloaded into the internal SRAM. This is followed by a remap and a jump to the first address of the SRAM. If no valid ARM vector sequence is found, NAND Flash Boot program is then executed. The NAND Flash Boot program looks for a sequence of seven valid ARM exception vectors. If such a sequence is found, code is downloaded into the internal SRAM. This is followed by a remap and a jump to the first address of the SRAM. If no valid ARM exception vector is found, the SDCard Boot program is then executed. It looks for a boot.bin file in the root directory of a FAT12/16/32 formatted SDCard. If such a file is found, code is downloaded into the internal SRAM. This is followed by a remap and a jump to the first address of the SRAM. If the SDCard is not formatted or if boot.bin file is not found, TWI Boot program is then executed. The TWI Boot program searches for a valid application in an EEPROM memory. If such a file is found, code is downloaded into the internal SRAM. This is followed by a remap and a jump to the first address of the SRAM. If no validapplication is found, SAM-BA Boot is then executed. It waits for transactions either on the USB device, or on the DBGU serial port. 13.2 Flow Diagram The Boot Program implements the algorithm in Figure 13-1. 73 6384D–ATARM–04-May-09 Figure 13-1. Boot Program Algorithm Flow Diagram Device Setup SPI Serialflash Boot NPCS0 Yes Download from Serial flash NPCS0 Run Serial Flash Boot NPCS0 No Timeout < 25 ms SPI Dataflash Boot NPCS0 Yes Download from Dataflash NPCS0 DataFlash Boot NPCS0 Run No Timeout < 25 ms SPI Serialflash Boot NPCS1 Yes Download from Serial flash NPCS1 Run Serial Flash Boot NPCS1 No Timeout < 25 ms SPI Dataflash Boot NPCS1 Yes Download from Dataflash NPCS1 DataFlash Boot NPCS1 Run No Timeout < 25 ms NandFlash Boot Yes Download from NandFlash Run NandFlash Boot No Timeout < 50ms SD Card Boot Yes Download from SDCARD Run SD Card Boot No Timeout < 50ms EEPROMBoot Yes Download from EEPROM Run TWI/EEPROM Boot No Timeout 50ms. Character(s) received on DBGU OR USB Enumeration Successful Run SAM-BA Boot SAM-BA Boot Run SAM-BA Boot 74 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 13.3 Device Initialization Initialization follows the steps described below: 1. Stack setup for ARM supervisor mode 2. Main Oscillator Frequency Detection 3. C variable initialization 4. PLL setup: PLLB is initialized to generate a 48 MHz clock necessary to use the USB Device. A register located in the Power Management Controller (PMC) determines the frequency of the main oscillator and thus the correct factor for the PLLB. – If internal RC Oscillator is used (OSCSEL = 0) and Main Oscillator is active, TTable 13-1 defines the crystals supported by the Boot Program when using the internal RC oscillator. als supported by the Boot Program. Table 13-1. Crystals Supported by Software Auto-Detection (MHz) 3.0 Boot in DBGU Boot on USB Note: Yes Yes 8.0 Yes Yes 18.432 Yes Yes Other Yes No Any other crystal can be used but it prevents using the USB. – If internal RC Oscillator is used (OSCSEL = 0) and Main Oscillator is bypassed, Table 13-2 defines the frequencies supported by the Boot Program when bypass-ing main oscillator. . Table 13-2. Crystals Supported by Software Auto-Detection (MHz) 3.0 Boot in DBGU Boot on USB Note: Yes Yes 8.0 Yes Yes 20 Yes Yes 50 Yes Yes Other Yes No Any other crystal can be used but it prevents using the USB. – If an external 32768 Hz Oscillator is used (OSCSEL = 1), defines the crystals supported by the Boot Program. Table 13-3 defines the crystals supported by the Boot Program. Table 13-3. 3.0 4.433619 6.0 7.3728 11.05920 14.7456 Note: Crystals Supported by Software Auto-Detection (MHz) 3.2768 4.608 6.144 7.864320 12.0 16.0 3.6864 4.9152 6.4 8.0 12.288 17.734470 3.84 5.0 6.5536 9.8304 13.56 18.432 4.0 5.24288 7.159090 10.0 14.31818 20.0 Booting either on USB or on DBGU is possible with any of these input frequencies. 75 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary – If an external 32768 Hz Oscillator is used (OSCSEL = 1) and Main Oscillator is bypassed. Table 13-4 defines the crystals supported by the Boot Program. Table 13-4. 3.0 4.433619 6.0 7.3728 11.05920 14.7456 24.0 33.0 Note: Input Frequencies Supported (OSCEL = 1) 3.2768 4.608 6.144 7.864320 12.0 16.0 24.576 40.0 3.6864 4.9152 6.4 8.0 12.288 17.734470 25.0 48.0 3.84 5.0 6.5536 9.8304 13.56 18.432 28.224 50 4.0 5.24288 7.159090 10.0 14.31818 20.0 32.0 Booting either on USB or on DBGU is possible with any of these input frequencies. 5. Initialization of the DBGU serial port (115200 bauds, 8, N, 1) 6. Jump to Serial Flash Boot sequence through NPCS0. If Serial Flash Boot succeeds, perform a remap and jump to 0x0. 7. Jump to DataFlash Boot sequence through NPCS0. If DataFlash Boot succeeds, perform a remap and jump to 0x0. 8. Jump to Serial Flash Boot sequence through NPCS1. If Serial Flash Boot succeeds, perform a remap and jump to 0x0. 9. Jump to DataFlash Boot sequence through NPCS1. If DataFlash Boot succeeds, perform a remap and jump to 0x0. 10. Jump to NAND Flash Boot sequence. If NAND Flash Boot succeeds, perform a remap and jump to 0x0. 11. Jump to SDCard Boot sequence. If SDCard Boot succeeds, perform a remap and jump to 0x0. 12. Jump to EEPROM Boot sequence. If EEPROM Boot succeeds, perform a remap and jump to 0x0. 13. Activation of the Instruction Cache 14. Jump to SAM-BA Boot sequence 15. Disable the WatchDog 16. Initialization of the USB Device Port 76 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Figure 13-2. Remap Action after Download Completion 0x0000_0000 Internal ROM REMAP 0x0020_0000 Internal SRAM Internal ROM 0x0010_0000 Internal SRAM 0x0000_0000 13.4 Valid Image Detection The DataFlash Boot software looks for a valid application by analyzing the first 28 bytes corresponding to the ARM exception vectors. These bytes must implement ARM instructions for either branch or load PC with PC relative addressing. The sixth vector, at offset 0x14, contains the size of the image to download. The user must replace this vector with his/her own vector (see “Structure of ARM Vector 6” on page 77). 13.4.1 Valid ARM exception vectors Figure 13-3. LDR Opcode 31 1 1 1 28 27 0 0 1 I 24 23 P U 0 W 20 19 1 Rn 16 15 Rd 12 11 0 Figure 13-4. B Opcode 31 1 1 1 28 27 0 1 0 1 24 23 0 Offset (24 bits) 0 Unconditional instruction: 0xE for bits 31 to 28 Load PC with PC relative addressing instruction: – Rn = Rd = PC = 0xF – I==0 – P==1 – U offset added (U==1) or subtracted (U==0) – W==1 13.4.2 Structure of ARM Vector 6 The ARM exception vector 6 is used to store information needed by the DataFlash boot program. This information is described below. 77 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Figure 13-5. Structure of the ARM Vector 6 31 Size of the code to download in bytes 0 13.4.2.1 Example An example of valid vectors follows: 00 04 08 0c 10 14 18 ea000006 eafffffe ea00002f eafffffe eafffffe 00001234 eafffffe B B B B B B B 0x20 0x04 _main 0x0c 0x10 0x14 0x18 ’. • Read commands: Read a byte (o), a halfword (h) or a word (w) from the target. – Address: Address in hexadecimal – Output: The byte, halfword or word read in hexadecimal following by ‘>’ • Send a file (S): Send a file to a specified address – Address: Address in hexadecimal – Output: ‘>’. Note: There is a time-out on this command which is reached when the prompt ‘>’ appears before the end of the command execution. • Receive a file (R): Receive data into a file from a specified address – Address: Address in hexadecimal – NbOfBytes: Number of bytes in hexadecimal to receive – Output: ‘>’ • Go (G): Jump to a specified address and execute the code – Address: Address to jump in hexadecimal – Output: ‘>’ • Get Version (V): Return the SAM-BA boot version – Output: ‘>’ 82 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 13.10.1 DBGU Serial Port Communication is performed through the DBGU serial port initialized to 115200 Baud, 8, n, 1. The Send and Receive File commands use the Xmodem protocol to communicate. Any terminal performing this protocol can be used to send the application file to the target. The size of the binary file to send depends on the SRAM size embedded in the product. In all cases, the size of the binary file must be lower than the SRAM size because the Xmodem protocol requires some SRAM memory to work. 13.10.2 Xmodem Protocol The Xmodem protocol supported is the 128-byte length block. This protocol uses a two-character CRC-16 to guarantee detection of a maximum bit error. Xmodem protocol with CRC is accurate provided both sender and receiver report successful transmission. Each block of the transfer looks like: in which: – = 01 hex – = binary number, starts at 01, increments by 1, and wraps 0FFH to 00H (not to 01) – = 1’s complement of the blk#. – = 2 bytes CRC16 Figure 13-8 shows a transmission using this protocol. Figure 13-8. Xmodem Transfer Example Host C SOH 01 FE Data[128] CRC CRC ACK SOH 02 FD Data[128] CRC CRC ACK SOH 03 FC Data[100] CRC CRC ACK EOT ACK Device 83 6384D–ATARM–04-May-09 13.10.3 USB Device Port A 48 MHz USB clock is necessary to use the USB Device port. It has been programmed earlier in the device initialization procedure with PLLB configuration. The device uses the USB communication device class (CDC) drivers to take advantage of the installed PC RS-232 software to talk over the USB. The CDC class is implemented in all releases of Windows®, from Windows 98SE to Windows XP®. The CDC document, available at www.usb.org, describes a way to implement devices such as ISDN modems and virtual COM ports. The Vendor ID is Atmel’s vendor ID 0x03EB. The product ID is 0x6124. These references are used by the host operating system to mount the correct driver. On Windows systems, the INF files contain the correspondence between vendor ID and product ID. Atmel provides an INF example to see the device as a new serial port and also provides another custom driver used by the SAM-BA application: atm6124.sys. Refer to the document “USB Basic Application”, literature number 6123, for more details. 13.10.3.1 Enumeration Process The USB protocol is a master/slave protocol. This is the host that starts the enumeration sending requests to the device through the control endpoint. The device handles standard requests as defined in the USB Specification. Table 13-6. Request GET_DESCRIPTOR SET_ADDRESS SET_CONFIGURATION GET_CONFIGURATION GET_STATUS SET_FEATURE CLEAR_FEATURE Handled Standard Requests Definition Returns the current device configuration value. Sets the device address for all future device access. Sets the device configuration. Returns the current device configuration value. Returns status for the specified recipient. Used to set or enable a specific feature. Used to clear or disable a specific feature. The device also handles some class requests defined in the CDC class. Table 13-7. Request SET_LINE_CODING GET_LINE_CODING SET_CONTROL_LINE_STATE Handled Class Requests Definition Configures DTE rate, stop bits, parity and number of character bits. Requests current DTE rate, stop bits, parity and number of character bits. RS-232 signal used to tell the DCE device the DTE device is now present. Unhandled requests are STALLed. 84 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 13.10.3.2 Communication Endpoints There are two communication endpoints and endpoint 0 is used for the enumeration process. Endpoint 1 is a 64-byte Bulk OUT endpoint and endpoint 2 is a 64-byte Bulk IN endpoint. SAMBA Boot commands are sent by the host through the endpoint 1. If required, the message is split by the host into several data payloads by the host driver. If the command requires a response, the host can send IN transactions to pick up the response. 85 6384D–ATARM–04-May-09 13.11 Hardware and Software Constraints • The DataFlash, Serial Flash, NAND Flash, SDCard(1), and EEPROM downloaded code size must be inferior to 16K bytes. • The code is always downloaded from the device address 0x0000_0000 to the address 0x0000_0000 of the internal SRAM (after remap). • The downloaded code must be position-independent or linked at address 0x0000_0000. • The DataFlash must be connected to NPCS0 of the SPI. Note: 1. Boot ROM does not support high capacity SDCards. The SPI and NAND Flash drivers use several PIOs in alternate functions to communicate with devices. Care must be taken when these PIOs are used by the application. The devices connected could be unintentionally driven at boot time, and electrical conflicts between SPI output pins and the connected devices may appear. To assure correct functionality, it is recommended to plug in critical devices to other pins. Table 13-8 contains a list of pins that are driven during the boot program execution. These pins are driven during the boot sequence for a period of less than 1 second if no correct boot program is found. Before performing the jump to the application in internal SRAM, all the PIOs and peripherals used in the boot program are set to their reset state. Table 13-8. Peripheral SPI0 SPI0 SPI0 SPI0 SPI0 PIOC Address Bus Address Bus MCI0 MCI0 MCI0 MCI0 MCI0 MCI0 TWI TWI DBGU DBGU Pins Driven during Boot Program Execution Pin MOSI MISO SPCK NPCS0 NPCS1 NANDCS NAND CLE NAND ALE MCDA0 MCCDA MCCK MCDA1 MCDA2 MCDA3 TWCK TWD DRXD DTXD PIO Line PIOA1 PIOA0 PIOA2 PIOA3 PIOC11 PIOC14 A22 A21 PIOA6 PIOA7 PIOA8 PIOA9 PIOA10 PIOA11 PIOA24 PIOA23 PIOB14 PIOB15 86 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 14. Reset Controller (RSTC) 14.1 Overview The Reset Controller (RSTC), based on power-on reset cells, handles all the resets of the system without any external components. It reports which reset occurred last. The Reset Controller also drives independently or simultaneously the external reset and the peripheral and processor resets. 14.2 Block Diagram Figure 14-1. Reset Controller Block Diagram Reset Controller Main Supply POR Backup Supply POR Startup Counter rstc_irq Reset State Manager proc_nreset user_reset NRST nrst_out NRST Manager exter_nreset periph_nreset backup_neset WDRPROC wd_fault SLCK 87 6384D–ATARM–04-May-09 14.3 14.3.1 Functional Description Reset Controller Overview The Reset Controller is made up of an NRST Manager, a Startup Counter and a Reset State Manager. It runs at Slow Clock and generates the following reset signals: • proc_nreset: Processor reset line. It also resets the Watchdog Timer. • backup_nreset: Affects all the peripherals powered by VDDBU. • periph_nreset: Affects the whole set of embedded peripherals. • nrst_out: Drives the NRST pin. These reset signals are asserted by the Reset Controller, either on external events or on software action. The Reset State Manager controls the generation of reset signals and provides a signal to the NRST Manager when an assertion of the NRST pin is required. The NRST Manager shapes the NRST assertion during a programmable time, thus controlling external device resets. The startup counter waits for the complete crystal oscillator startup. The wait delay is given by the crystal oscillator startup time maximum value that can be found in the section Crystal Oscillator Characteristics in the Electrical Characteristics section of the product documentation. The Reset Controller Mode Register (RSTC_MR), allowing the configuration of the Reset Controller, is powered with VDDBU, so that its configuration is saved as long as VDDBU is on. 14.3.2 NRST Manager The NRST Manager samples the NRST input pin and drives this pin low when required by the Reset State Manager. Figure 14-2 shows the block diagram of the NRST Manager. Figure 14-2. NRST Manager RSTC_MR RSTC_SR URSTIEN rstc_irq RSTC_MR URSTS NRSTL Other interrupt sources user_reset URSTEN NRST RSTC_MR ERSTL nrst_out External Reset Timer exter_nreset 14.3.2.1 NRST Signal or Interrupt The NRST Manager samples the NRST pin at Slow Clock speed. When the line is detected low, a User Reset is reported to the Reset State Manager. However, the NRST Manager can be programmed to not trigger a reset when an assertion of NRST occurs. Writing the bit URSTEN at 0 in RSTC_MR disables the User Reset trigger. 88 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary The level of the pin NRST can be read at any time in the bit NRSTL (NRST level) in RSTC_SR. As soon as the pin NRST is asserted, the bit URSTS in RSTC_SR is set. This bit clears only when RSTC_SR is read. The Reset Controller can also be programmed to generate an interrupt instead of generating a reset. To do so, the bit URSTIEN in RSTC_MR must be written at 1. 14.3.2.2 NRST External Reset Control The Reset State Manager asserts the signal ext_nreset to assert the NRST pin. When this occurs, the “nrst_out” signal is driven low by the NRST Manager for a time programmed by the field ERSTL in RSTC_MR. This assertion duration, named EXTERNAL_RESET_LENGTH, lasts 2(ERSTL+1) Slow Clock cycles. This gives the approximate duration of an assertion between 60 µs and 2 seconds. Note that ERSTL at 0 defines a two-cycle duration for the NRST pulse. This feature allows the Reset Controller to shape the NRST pin level, and thus to guarantee that the NRST line is driven low for a time compliant with potential external devices connected on the system reset. As the field is within RSTC_MR, which is backed-up, this field can be used to shape the system power-up reset for devices requiring a longer startup time than the Slow Clock Oscillator. 14.3.3 BMS Sampling The product matrix manages a boot memory that depends on the level on the BMS pin at reset. The BMS signal is sampled three slow clock cycles after the Core Power-On-Reset output rising edge. Figure 14-3. BMS Sampling SLCK Core Supply POR output XXX BMS sampling delay = 3 cycles BMS Signal H or L proc_nreset 14.3.4 Reset States The Reset State Manager handles the different reset sources and generates the internal reset signals. It reports the reset status in the field RSTTYP of the Status Register (RSTC_SR). The update of the field RSTTYP is performed when the processor reset is released. 14.3.4.1 General Reset A general reset occurs when VDDBU and VDDCORE are powered on. The backup supply POR cell output rises and is filtered with a Startup Counter, which operates at Slow Clock. The purpose of this counter is to make sure the Slow Clock oscillator is stable before starting up the 89 6384D–ATARM–04-May-09 device. The length of startup time is hardcoded to comply with the Slow Clock Oscillator startup time. After this time, the processor clock is released at Slow Clock and all the other signals remain valid for 3 cycles for proper processor and logic reset. Then, all the reset signals are released and the field RSTTYP in RSTC_SR reports a General Reset. As the RSTC_MR is reset, the NRST line rises 2 cycles after the backup_nreset, as ERSTL defaults at value 0x0. When VDDBU is detected low by the Backup Supply POR Cell, all resets signals are immediately asserted, even if the Main Supply POR Cell does not report a Main Supply shutdown. VDDBU only activates the backup_nreset signal. The backup_nreset must be released so that any other reset can be generated by VDDCORE (Main Supply POR output). Figure 14-4 shows how the General Reset affects the reset signals. Figure 14-4. General Reset State SLCK MCK Backup Supply POR output Any Freq. Startup Time Main Supply POR output backup_nreset Processor Startup = 3 cycles proc_nreset RSTTYP periph_nreset XXX 0x0 = General Reset XXX NRST (nrst_out) BMS Sampling EXTERNAL RESET LENGTH = 2 cycles 90 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 14.3.4.2 Wake-up Reset The Wake-up Reset occurs when the Main Supply is down. When the Main Supply POR output is active, all the reset signals are asserted except backup_nreset. When the Main Supply powers up, the POR output is resynchronized on Slow Clock. The processor clock is then re-enabled during 3 Slow Clock cycles, depending on the requirements of the ARM processor. At the end of this delay, the processor and other reset signals rise. The field RSTTYP in RSTC_SR is updated to report a Wake-up Reset. The “nrst_out” remains asserted for EXTERNAL_RESET_LENGTH cycles. As RSTC_MR is backed-up, the programmed number of cycles is applicable. When the Main Supply is detected falling, the reset signals are immediately asserted. This transition is synchronous with the output of the Main Supply POR. Figure 14-5. Wake-up State SLCK MCK Main Supply POR output Any Freq. backup_nreset Resynch. 2 cycles Processor Startup = 3 cycles proc_nreset RSTTYP XXX 0x1 = WakeUp Reset XXX periph_nreset NRST (nrst_out) EXTERNAL RESET LENGTH = 4 cycles (ERSTL = 1) 14.3.4.3 User Reset The User Reset is entered when a low level is detected on the NRST pin and the bit URSTEN in RSTC_MR is at 1. The NRST input signal is resynchronized with SLCK to insure proper behavior of the system. The User Reset is entered as soon as a low level is detected on NRST. The Processor Reset and the Peripheral Reset are asserted. The User Reset is left when NRST rises, after a two-cycle resynchronization time and a 3-cycle processor startup. The processor clock is re-enabled as soon as NRST is confirmed high. 91 6384D–ATARM–04-May-09 When the processor reset signal is released, the RSTTYP field of the Status Register (RSTC_SR) is loaded with the value 0x4, indicating a User Reset. The NRST Manager guarantees that the NRST line is asserted for EXTERNAL_RESET_LENGTH Slow Clock cycles, as programmed in the field ERSTL. However, if NRST does not rise after EXTERNAL_RESET_LENGTH because it is driven low externally, the internal reset lines remain asserted until NRST actually rises. Figure 14-6. User Reset State SLCK MCK Any Freq. NRST Resynch. 2 cycles Resynch. 2 cycles Processor Startup = 3 cycles proc_nreset RSTTYP periph_nreset Any XXX 0x4 = User Reset NRST (nrst_out) >= EXTERNAL RESET LENGTH 14.3.4.4 Software Reset The Reset Controller offers several commands used to assert the different reset signals. These commands are performed by writing the Control Register (RSTC_CR) with the following bits at 1: • PROCRST: Writing PROCRST at 1 resets the processor and the watchdog timer. • PERRST: Writing PERRST at 1 resets all the embedded peripherals, including the memory system, and, in particular, the Remap Command. The Peripheral Reset is generally used for debug purposes. • EXTRST: Writing EXTRST at 1 asserts low the NRST pin during a time defined by the field ERSTL in the Mode Register (RSTC_MR). The software reset is entered if at least one of these bits is set by the software. All these commands can be performed independently or simultaneously. The software reset lasts 3 Slow Clock cycles. The internal reset signals are asserted as soon as the register write is performed. This is detected on the Master Clock (MCK). They are released when the software reset is left, i.e.; synchronously to SLCK. 92 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary If EXTRST is set, the nrst_out signal is asserted depending on the programming of the field ERSTL. However, the resulting falling edge on NRST does not lead to a User Reset. If and only if the PROCRST bit is set, the Reset Controller reports the software status in the field RSTTYP of the Status Register (RSTC_SR). Other Software Resets are not reported in RSTTYP. As soon as a software operation is detected, the bit SRCMP (Software Reset Command in Progress) is set in the Status Register (RSTC_SR). It is cleared as soon as the software reset is left. No other software reset can be performed while the SRCMP bit is set, and writing any value in RSTC_CR has no effect. Figure 14-7. Software Reset SLCK MCK Any Freq. Write RSTC_CR Resynch. 1 cycle Processor Startup = 3 cycles proc_nreset if PROCRST=1 RSTTYP periph_nreset if PERRST=1 NRST (nrst_out) if EXTRST=1 EXTERNAL RESET LENGTH 8 cycles (ERSTL=2) Any XXX 0x3 = Software Reset SRCMP in RSTC_SR 14.3.4.5 Watchdog Reset The Watchdog Reset is entered when a watchdog fault occurs. This state lasts 3 Slow Clock cycles. When in Watchdog Reset, assertion of the reset signals depends on the WDRPROC bit in WDT_MR: • If WDRPROC is 0, the Processor Reset and the Peripheral Reset are asserted. The NRST line is also asserted, depending on the programming of the field ERSTL. However, the resulting low level on NRST does not result in a User Reset state. • If WDRPROC = 1, only the processor reset is asserted. The Watchdog Timer is reset by the proc_nreset signal. As the watchdog fault always causes a processor reset if WDRSTEN is set, the Watchdog Timer is always reset after a Watchdog Reset, and the Watchdog is enabled by default and with a period set to a maximum. 93 6384D–ATARM–04-May-09 When the WDRSTEN in WDT_MR bit is reset, the watchdog fault has no impact on the reset controller. Figure 14-8. Watchdog Reset SLCK MCK Any Freq. wd_fault Processor Startup = 3 cycles proc_nreset RSTTYP periph_nreset Only if WDRPROC = 0 Any XXX 0x2 = Watchdog Reset NRST (nrst_out) EXTERNAL RESET LENGTH 8 cycles (ERSTL=2) 14.3.5 Reset State Priorities The Reset State Manager manages the following priorities between the different reset sources, given in descending order: • Backup Reset • Wake-up Reset • Watchdog Reset • Software Reset • User Reset Particular cases are listed below: • When in User Reset: – A watchdog event is impossible because the Watchdog Timer is being reset by the proc_nreset signal. – A software reset is impossible, since the processor reset is being activated. • When in Software Reset: – A watchdog event has priority over the current state. – The NRST has no effect. • When in Watchdog Reset: – The processor reset is active and so a Software Reset cannot be programmed. – A User Reset cannot be entered. 94 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 14.3.6 Reset Controller Status Register The Reset Controller status register (RSTC_SR) provides several status fields: • RSTTYP field: This field gives the type of the last reset, as explained in previous sections. • SRCMP bit: This field indicates that a Software Reset Command is in progress and that no further software reset should be performed until the end of the current one. This bit is automatically cleared at the end of the current software reset. • NRSTL bit: The NRSTL bit of the Status Register gives the level of the NRST pin sampled on each MCK rising edge. • URSTS bit: A high-to-low transition of the NRST pin sets the URSTS bit of the RSTC_SR register. This transition is also detected on the Master Clock (MCK) rising edge (see Figure 14-9). If the User Reset is disabled (URSTEN = 0) and if the interruption is enabled by the URSTIEN bit in the RSTC_MR register, the URSTS bit triggers an interrupt. Reading the RSTC_SR status register resets the URSTS bit and clears the interrupt. Figure 14-9. Reset Controller Status and Interrupt MCK read RSTC_SR Peripheral Access 2 cycle resynchronization NRST NRSTL 2 cycle resynchronization URSTS rstc_irq if (URSTEN = 0) and (URSTIEN = 1) 95 6384D–ATARM–04-May-09 14.4 Reset Controller (RSTC) User Interface Register Mapping Register Control Register Status Register Mode Register Name RSTC_CR RSTC_SR RSTC_MR Access Write-only Read-only Read-write Reset Value 0x0000_0001 0x0000_0000 0x0000_0000 Back-up Reset Value Table 14-1. Offset 0x00 0x04 0x08 Note: 1. The reset value of RSTC_SR either reports a General Reset or a Wake-up Reset depending on last rising power supply. 96 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 14.4.1 Name: Reset Controller Control Register RSTC_CR Access Type:Write-only 31 30 29 28 KEY 23 – 15 – 7 – 22 – 14 – 6 – 21 – 13 – 5 – 20 – 12 – 4 – 19 – 11 – 3 EXTRST 18 – 10 – 2 PERRST 17 – 9 16 – 8 – 0 PROCRST 27 26 25 24 1 – • PROCRST: Processor Reset 0 = No effect. 1 = If KEY is correct, resets the processor. • PERRST: Peripheral Reset 0 = No effect. 1 = If KEY is correct, resets the peripherals. • EXTRST: External Reset 0 = No effect. 1 = If KEY is correct, asserts the NRST pin. • KEY: Password Should be written at value 0xA5. Writing any other value in this field aborts the write operation. 97 6384D–ATARM–04-May-09 14.4.2 Name: Reset Controller Status Register RSTC_SR Access Type:Read-only 31 – 23 – 15 – 7 – 30 – 22 – 14 – 6 – 29 – 21 – 13 – 5 – 28 – 20 – 12 – 4 – 27 – 19 – 11 – 3 – 26 – 18 – 10 25 – 17 SRCMP 9 RSTTYP 1 – 24 – 16 NRSTL 8 2 – 0 URSTS • URSTS: User Reset Status 0 = No high-to-low edge on NRST happened since the last read of RSTC_SR. 1 = At least one high-to-low transition of NRST has been detected since the last read of RSTC_SR. • RSTTYP: Reset Type Reports the cause of the last processor reset. Reading this RSTC_SR does not reset this field. RSTTYP 0 0 0 0 1 0 0 1 1 0 0 1 0 1 0 Reset Type General Reset Wake Up Reset Watchdog Reset Software Reset User Reset Comments Both VDDCORE and VDDBU rising VDDCORE rising Watchdog fault occurred Processor reset required by the software NRST pin detected low • NRSTL: NRST Pin Level Registers the NRST Pin Level at Master Clock (MCK). • SRCMP: Software Reset Command in Progress 0 = No software command is being performed by the reset controller. The reset controller is ready for a software command. 1 = A software reset command is being performed by the reset controller. The reset controller is busy. 98 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 14.4.3 Name: Reset Controller Mode Register RSTC_MR Access Type:Read-write 31 30 29 28 KEY 23 – 15 – 7 – 22 – 14 – 6 – 21 – 13 – 5 20 – 12 – 4 URSTIEN 19 – 11 18 – 10 ERSTL 3 – 2 – 1 – 0 URSTEN 17 – 9 16 27 26 25 24 8 • URSTEN: User Reset Enable 0 = The detection of a low level on the pin NRST does not generate a User Reset. 1 = The detection of a low level on the pin NRST triggers a User Reset. • URSTIEN: User Reset Interrupt Enable 0 = USRTS bit in RSTC_SR at 1 has no effect on rstc_irq. 1 = USRTS bit in RSTC_SR at 1 asserts rstc_irq if URSTEN = 0. • ERSTL: External Reset Length This field defines the external reset length. The external reset is asserted during a time of 2(ERSTL+1) Slow Clock cycles. This allows assertion duration to be programmed between 60 µs and 2 seconds. • KEY: Password Should be written at value 0xA5. Writing any other value in this field aborts the write operation. 99 6384D–ATARM–04-May-09 100 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 15. Real-time Timer (RTT) 15.1 Overview The Real-time Timer is built around a 32-bit counter and used to count elapsed seconds. It generates a periodic interrupt and/or triggers an alarm on a programmed value. 15.2 Block Diagram Figure 15-1. Real-time Timer RTT_MR RTTRST RTT_MR RTPRES RTT_MR SLCK reload 16-bit Divider RTT_MR RTTRST 1 0 RTTINCIEN 0 RTT_SR set RTTINC reset rtt_int 32-bit Counter read RTT_SR RTT_MR ALMIEN RTT_VR CRTV RTT_SR reset ALMS set = RTT_AR ALMV rtt_alarm 15.3 Functional Description The Real-time Timer is used to count elapsed seconds. It is built around a 32-bit counter fed by Slow Clock divided by a programmable 16-bit value. The value can be programmed in the field RTPRES of the Real-time Mode Register (RTT_MR). Programming RTPRES at 0x00008000 corresponds to feeding the real-time counter with a 1 Hz signal (if the Slow Clock is 32.768 Hz). The 32-bit counter can count up to 232 seconds, corresponding to more than 136 years, then roll over to 0. The Real-time Timer can also be used as a free-running timer with a lower time-base. The best accuracy is achieved by writing RTPRES to 3. Programming RTPRES to 1 or 2 is possible, but may result in losing status events because the status register is cleared two Slow Clock cycles after read. Thus if the RTT is configured to trigger an interrupt, the interrupt occurs during 2 Slow Clock cycles after reading RTT_SR. To prevent several executions of the interrupt handler, the interrupt must be disabled in the interrupt handler and re-enabled when the status register is clear. 101 6384D–ATARM–04-May-09 The Real-time Timer value (CRTV) can be read at any time in the register RTT_VR (Real-time Value Register). As this value can be updated asynchronously from the Master Clock, it is advisable to read this register twice at the same value to improve accuracy of the returned value. The current value of the counter is compared with the value written in the alarm register RTT_AR (Real-time Alarm Register). If the counter value matches the alarm, the bit ALMS in RTT_SR is set. The alarm register is set to its maximum value, corresponding to 0xFFFF_FFFF, after a reset. The bit RTTINC in RTT_SR is set each time the Real-time Timer counter is incremented. This bit can be used to start a periodic interrupt, the period being one second when the RTPRES is programmed with 0x8000 and Slow Clock equal to 32.768 Hz. Reading the RTT_SR status register resets the RTTINC and ALMS fields. Writing the bit RTTRST in RTT_MR immediately reloads and restarts the clock divider with the new programmed value. This also resets the 32-bit counter. Note: Because of the asynchronism between the Slow Clock (SCLK) and the System Clock (MCK): 1) The restart of the counter and the reset of the RTT_VR current value register is effective only 2 slow clock cycles after the write of the RTTRST bit in the RTT_MR register. 2) The status register flags reset is taken into account only 2 slow clock cycles after the read of the RTT_SR (Status Register). Figure 15-2. RTT Counting APB cycle APB cycle MCK RTPRES - 1 Prescaler 0 RTT 0 ... ALMV-1 ALMV ALMV+1 ALMV+2 ALMV+3 RTTINC (RTT_SR) ALMS (RTT_SR) APB Interface read RTT_SR 102 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 15.4 Real-time Timer (RTT) User Interface Register Mapping Register Mode Register Alarm Register Value Register Status Register Name RTT_MR RTT_AR RTT_VR RTT_SR Access Read-write Read-write Read-only Read-only Reset 0x0000_8000 0xFFFF_FFFF 0x0000_0000 0x0000_0000 Table 15-1. Offset 0x00 0x04 0x08 0x0C 103 6384D–ATARM–04-May-09 15.4.1 Real-time Timer Mode Register Register Name: RTT_MR Access Type: Read/Write 31 – 23 – 15 30 – 22 – 14 29 – 21 – 13 28 – 20 – 12 RTPRES 7 6 5 4 RTPRES 3 2 1 0 27 – 19 – 11 26 – 18 RTTRST 10 25 – 17 RTTINCIEN 9 24 – 16 ALMIEN 8 • RTPRES: Real-time Timer Prescaler Value Defines the number of SLCK periods required to increment the Real-time timer. RTPRES is defined as follows: RTPRES = 0: The prescaler period is equal to 216. RTPRES …0: The prescaler period is equal to RTPRES. • ALMIEN: Alarm Interrupt Enable 0 = The bit ALMS in RTT_SR has no effect on interrupt. 1 = The bit ALMS in RTT_SR asserts interrupt. • RTTINCIEN: Real-time Timer Increment Interrupt Enable 0 = The bit RTTINC in RTT_SR has no effect on interrupt. 1 = The bit RTTINC in RTT_SR asserts interrupt. • RTTRST: Real-time Timer Restart 1 = Reloads and restarts the clock divider with the new programmed value. This also resets the 32-bit counter. 104 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 15.4.2 Real-time Timer Alarm Register Register Name: RTT_AR Access Type: Read/Write 31 30 29 28 ALMV 23 22 21 20 ALMV 15 14 13 12 ALMV 7 6 5 4 ALMV 3 2 1 0 11 10 9 8 19 18 17 16 27 26 25 24 • ALMV: Alarm Value Defines the alarm value (ALMV+1) compared with the Real-time Timer. 15.4.3 Real-time Timer Value Register Register Name: RTT_VR Access Type: Read-only 31 30 29 28 CRTV 23 22 21 20 CRTV 15 14 13 12 CRTV 7 6 5 4 CRTV 3 2 1 0 11 10 9 8 19 18 17 16 27 26 25 24 • CRTV: Current Real-time Value Returns the current value of the Real-time Timer. 105 6384D–ATARM–04-May-09 15.4.4 Real-time Timer Status Register Register Name: RTT_SR Access Type: Read-only 31 – 23 – 15 – 7 – 30 – 22 – 14 – 6 – 29 – 21 – 13 – 5 – 28 – 20 – 12 – 4 – 27 – 19 – 11 – 3 – 26 – 18 – 10 – 2 – 25 – 17 – 9 – 1 RTTINC 24 – 16 – 8 – 0 ALMS • ALMS: Real-time Alarm Status 0 = The Real-time Alarm has not occurred since the last read of RTT_SR. 1 = The Real-time Alarm occurred since the last read of RTT_SR. • RTTINC: Real-time Timer Increment 0 = The Real-time Timer has not been incremented since the last read of the RTT_SR. 1 = The Real-time Timer has been incremented since the last read of the RTT_SR. 106 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 16. Periodic Interval Timer (PIT) 16.1 Overview The Periodic Interval Timer (PIT) provides the operating system’s scheduler interrupt. It is designed to offer maximum accuracy and efficient management, even for systems with long response time. 16.2 Block Diagram Figure 16-1. Periodic Interval Timer PIT_MR PIV =? PIT_MR PITIEN set 0 PIT_SR PITS reset pit_irq 0 0 1 0 1 12-bit Adder read PIT_PIVR MCK 20-bit Counter Prescaler MCK/16 CPIV PIT_PIVR PICNT CPIV PIT_PIIR PICNT 16.3 Functional Description The Periodic Interval Timer aims at providing periodic interrupts for use by operating systems. The PIT provides a programmable overflow counter and a reset-on-read feature. It is built around two counters: a 20-bit CPIV counter and a 12-bit PICNT counter. Both counters work at Master Clock /16. The first 20-bit CPIV counter increments from 0 up to a programmable overflow value set in the field PIV of the Mode Register (PIT_MR). When the counter CPIV reaches this value, it resets to 0 and increments the Periodic Interval Counter, PICNT. The status bit PITS in the Status Register (PIT_SR) rises and triggers an interrupt, provided the interrupt is enabled (PITIEN in PIT_MR). 107 6384D–ATARM–04-May-09 Writing a new PIV value in PIT_MR does not reset/restart the counters. When CPIV and PICNT values are obtained by reading the Periodic Interval Value Register (PIT_PIVR), the overflow counter (PICNT) is reset and the PITS is cleared, thus acknowledging the interrupt. The value of PICNT gives the number of periodic intervals elapsed since the last read of PIT_PIVR. When CPIV and PICNT values are obtained by reading the Periodic Interval Image Register (PIT_PIIR), there is no effect on the counters CPIV and PICNT, nor on the bit PITS. For example, a profiler can read PIT_PIIR without clearing any pending interrupt, whereas a timer interrupt clears the interrupt by reading PIT_PIVR. The PIT may be enabled/disabled using the PITEN bit in the PIT_MR register (disabled on reset). The PITEN bit only becomes effective when the CPIV value is 0. Figure 16-2 illustrates the PIT counting. After the PIT Enable bit is reset (PITEN= 0), the CPIV goes on counting until the PIV value is reached, and is then reset. PIT restarts counting, only if the PITEN is set again. The PIT is stopped when the core enters debug state. Figure 16-2. Enabling/Disabling PIT with PITEN APB cycle MCK 15 restarts MCK Prescaler MCK Prescaler 0 PITEN APB cycle CPIV PICNT PITS (PIT_SR) APB Interface 0 1 0 PIV - 1 PIV 1 0 0 1 read PIT_PIVR 108 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 16.4 Periodic Interval Timer (PIT) User Interface Register Mapping Register Mode Register Status Register Periodic Interval Value Register Periodic Interval Image Register Name PIT_MR PIT_SR PIT_PIVR PIT_PIIR Access Read-write Read-only Read-only Read-only Reset 0x000F_FFFF 0x0000_0000 0x0000_0000 0x0000_0000 Table 16-1. Offset 0x00 0x04 0x08 0x0C 109 6384D–ATARM–04-May-09 16.4.1 Name: Access: 31 – 23 – 15 Periodic Interval Timer Mode Register PIT_MR Read/Write 30 – 22 – 14 29 – 21 – 13 28 – 20 – 12 PIV 7 6 5 4 PIV 3 2 1 0 27 – 19 26 – 18 PIV 11 10 9 8 25 PITIEN 17 24 PITEN 16 • PIV: Periodic Interval Value Defines the value compared with the primary 20-bit counter of the Periodic Interval Timer (CPIV). The period is equal to (PIV + 1). • PITEN: Period Interval Timer Enabled 0 = The Periodic Interval Timer is disabled when the PIV value is reached. 1 = The Periodic Interval Timer is enabled. • PITIEN: Periodic Interval Timer Interrupt Enable 0 = The bit PITS in PIT_SR has no effect on interrupt. 1 = The bit PITS in PIT_SR asserts interrupt. 110 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 16.4.2 Name: Access: 31 – 23 – 15 – 7 – Periodic Interval Timer Status Register PIT_SR Read-only 30 – 22 – 14 – 6 – 29 – 21 – 13 – 5 – 28 – 20 – 12 – 4 – 27 – 19 – 11 – 3 – 26 – 18 – 10 – 2 – 25 – 17 – 9 – 1 – 24 – 16 – 8 – 0 PITS • PITS: Periodic Interval Timer Status 0 = The Periodic Interval timer has not reached PIV since the last read of PIT_PIVR. 1 = The Periodic Interval timer has reached PIV since the last read of PIT_PIVR. 16.4.3 Name: Access: 31 Periodic Interval Timer Value Register PIT_PIVR Read-only 30 29 28 PICNT 27 26 25 24 23 22 PICNT 21 20 19 18 CPIV 17 16 15 14 13 12 CPIV 11 10 9 8 7 6 5 4 CPIV 3 2 1 0 Reading this register clears PITS in PIT_SR. • CPIV: Current Periodic Interval Value Returns the current value of the periodic interval timer. • PICNT: Periodic Interval Counter Returns the number of occurrences of periodic intervals since the last read of PIT_PIVR. 111 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 16.4.4 Name: Access: 31 Periodic Interval Timer Image Register PIT_PIIR Read-only 30 29 28 PICNT 27 26 25 24 23 22 PICNT 21 20 19 18 CPIV 17 16 15 14 13 12 CPIV 11 10 9 8 7 6 5 4 CPIV 3 2 1 0 • CPIV: Current Periodic Interval Value Returns the current value of the periodic interval timer. • PICNT: Periodic Interval Counter Returns the number of occurrences of periodic intervals since the last read of PIT_PIVR. 112 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 17. Watchdog Timer (WDT) 17.1 Overview The Watchdog Timer can be used to prevent system lock-up if the software becomes trapped in a deadlock. It features a 12-bit down counter that allows a watchdog period of up to 16 seconds (slow clock at 32.768 kHz). It can generate a general reset or a processor reset only. In addition, it can be stopped while the processor is in debug mode or idle mode. 17.2 Block Diagram Figure 17-1. Watchdog Timer Block Diagram write WDT_MR WDT_MR WDT_CR WDRSTT reload 1 0 WDV 12-bit Down Counter WDT_MR WDD Current Value reload 1/128 SLCK bit MREAD = 0 Load Transmit register TWI_THR = Data to send Read Status register No TXRDY = 1? Yes Read Status register No TXCOMP = 1? Yes Transfer finished 427 6384D–ATARM–04-May-09 Figure 31-15. TWI Write Operation with Single Data Byte and Internal Address BEGIN Set TWI clock (CLDIV, CHDIV, CKDIV) in TWI_CWGR (Needed only once) Set the Control register: - Master enable TWI_CR = MSEN + SVDIS Set the Master Mode register: - Device slave address (DADR) - Internal address size (IADRSZ) - Transfer direction bit Write ==> bit MREAD = 0 Set the internal address TWI_IADR = address Load transmit register TWI_THR = Data to send Read Status register No TXRDY = 1? Yes Read Status register TXCOMP = 1? No Yes Transfer finished 428 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Figure 31-16. TWI Write Operation with Multiple Data Bytes with or without Internal Address BEGIN Set TWI clock (CLDIV, CHDIV, CKDIV) in TWI_CWGR (Needed only once) Set the Control register: - Master enable TWI_CR = MSEN + SVDIS Set the Master Mode register: - Device slave address - Internal address size (if IADR used) - Transfer direction bit Write ==> bit MREAD = 0 No Internal address size = 0? Set the internal address TWI_IADR = address Yes Load Transmit register TWI_THR = Data to send Read Status register TWI_THR = data to send TXRDY = 1? Yes Data to send? Yes No Read Status register Yes No TXCOMP = 1? END 429 6384D–ATARM–04-May-09 Figure 31-17. TWI Read Operation with Single Data Byte without Internal Address BEGIN Set TWI clock (CLDIV, CHDIV, CKDIV) in TWI_CWGR (Needed only once) Set the Control register: - Master enable TWI_CR = MSEN + SVDIS Set the Master Mode register: - Device slave address - Transfer direction bit Read ==> bit MREAD = 1 Start the transfer TWI_CR = START | STOP Read status register RXRDY = 1? Yes Read Receive Holding Register No Read Status register No TXCOMP = 1? Yes END 430 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Figure 31-18. TWI Read Operation with Single Data Byte and Internal Address BEGIN Set TWI clock (CLDIV, CHDIV, CKDIV) in TWI_CWGR (Needed only once) Set the Control register: - Master enable TWI_CR = MSEN + SVDIS Set the Master Mode register: - Device slave address - Internal address size (IADRSZ) - Transfer direction bit Read ==> bit MREAD = 1 Set the internal address TWI_IADR = address Start the transfer TWI_CR = START | STOP Read Status register No RXRDY = 1? Yes Read Receive Holding register Read Status register No TXCOMP = 1? Yes END 431 6384D–ATARM–04-May-09 Figure 31-19. TWI Read Operation with Multiple Data Bytes with or without Internal Address BEGIN Set TWI clock (CLDIV, CHDIV, CKDIV) in TWI_CWGR (Needed only once) Set the Control register: - Master enable TWI_CR = MSEN + SVDIS Set the Master Mode register: - Device slave address - Internal address size (if IADR used) - Transfer direction bit Read ==> bit MREAD = 1 Internal address size = 0? Set the internal address TWI_IADR = address Yes Start the transfer TWI_CR = START Read Status register RXRDY = 1? Yes Read Receive Holding register (TWI_RHR) No No Last data to read but one? Yes Stop the transfer TWI_CR = STOP Read Status register No RXRDY = 1? Yes Read Receive Holding register (TWI_RHR) Read status register TXCOMP = 1? Yes END No 432 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 31.8 31.8.1 Multi-master Mode Definition More than one master may handle the bus at the same time without data corruption by using arbitration. Arbitration starts as soon as two or more masters place information on the bus at the same time, and stops (arbitration is lost) for the master that intends to send a logical one while the other master sends a logical zero. As soon as arbitration is lost by a master, it stops sending data and listens to the bus in order to detect a stop. When the stop is detected, the master who has lost arbitration may put its data on the bus by respecting arbitration. Arbitration is illustrated in Figure 31-21 on page 434. 31.8.2 Different Multi-master Modes Two multi-master modes may be distinguished: 1. TWI is considered as a Master only and will never be addressed. 2. TWI may be either a Master or a Slave and may be addressed. Note: In both Multi-master modes arbitration is supported. 31.8.2.1 TWI as Master Only In this mode, TWI is considered as a Master only (MSEN is always at one) and must be driven like a Master with the ARBLST (ARBitration Lost) flag in addition. If arbitration is lost (ARBLST = 1), the programmer must reinitiate the data transfer. If the user starts a transfer (ex.: DADR + START + W + Write in THR) and if the bus is busy, the TWI automatically waits for a STOP condition on the bus to initiate the transfer (see Figure 3120 on page 434). Note: The state of the bus (busy or free) is not indicated in the user interface. 31.8.2.2 TWI as Master or Slave The automatic reversal from Master to Slave is not supported in case of a lost arbitration. Then, in the case where TWI may be either a Master or a Slave, the programmer must manage the pseudo Multi-master mode described in the steps below. 1. Program TWI in Slave mode (SADR + MSDIS + SVEN) and perform Slave Access (if TWI is addressed). 2. If TWI has to be set in Master mode, wait until TXCOMP flag is at 1. 3. Program Master mode (DADR + SVDIS + MSEN) and start the transfer (ex: START + Write in THR). 4. As soon as the Master mode is enabled, TWI scans the bus in order to detect if it is busy or free. When the bus is considered as free, TWI initiates the transfer. 5. As soon as the transfer is initiated and until a STOP condition is sent, the arbitration becomes relevant and the user must monitor the ARBLST flag. 6. If the arbitration is lost (ARBLST is set to 1), the user must program the TWI in Slave mode in the case where the Master that won the arbitration wanted to access the TWI. 7. If TWI has to be set in Slave mode, wait until TXCOMP flag is at 1 and then program the Slave mode. 433 6384D–ATARM–04-May-09 Note: In the case where the arbitration is lost and TWI is addressed, TWI will not acknowledge even if it is programmed in Slave mode as soon as ARBLST is set to 1. Then, the Master must repeat SADR. Figure 31-20. Programmer Sends Data While the Bus is Busy TWCK STOP sent by the master TWD DATA sent by a master Bus is busy Bus is free TWI DATA transfer Transfer is kept START sent by the TWI DATA sent by the TWI A transfer is programmed (DADR + W + START + Write THR) Bus is considered as free Transfer is initiated Figure 31-21. Arbitration Cases TWCK TWD TWCK Data from a Master Data from TWI TWD S S S 1 1 1 0 0 11 0 1 Arbitration is lost TWI stops sending data P S S 1 1 1 0 1 Arbitration is lost The master stops sending data 0 01 0 01 1 1 Data from the TWI 00 11 Data from the master P S ARBLST Bus is busy Bus is free TWI DATA transfer A transfer is programmed (DADR + W + START + Write THR) Transfer is stopped Transfer is kept Transfer is programmed again (DADR + W + START + Write THR) Bus is considered as free Transfer is initiated The flowchart shown in Figure 31-22 on page 435 gives an example of read and write operations in Multi-master mode. 434 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Figure 31-22. Multi-master Flowchart START Programm the SLAVE mode: SADR + MSDIS + SVEN Read Status Register SVACC = 1 ? No No EOSACC = 1 ? Yes No TXCOMP = 1 ? Yes No Yes GACC = 1 ? No No No SVREAD = 0 ? Yes TXRDY= 1 ? Yes Write in TWI_THR RXRDY= 0 ? Yes Read TWI_RHR No Need to perform a master access ? GENERAL CALL TREATMENT Yes Decoding of the programming sequence Prog seq OK ? Change SADR Program the Master mode DADR + SVDIS + MSEN + CLK + R / W No Read Status Register Yes ARBLST = 1 ? No Yes Yes MREAD = 1 ? No Yes RXRDY= 0 ? No TXRDY= 0 ? No Data to send ? No Stop transfer Read TWI_RHR Yes Data to read? No Yes Write in TWI_THR Read Status Register Yes No TXCOMP = 0 ? 435 6384D–ATARM–04-May-09 31.9 31.9.1 Slave Mode Definition The Slave Mode is defined as a mode where the device receives the clock and the address from another device called the master. In this mode, the device never initiates and never completes the transmission (START, REPEATED_START and STOP conditions are always provided by the master). 31.9.2 Application Block Diagram Figure 31-23. Slave Mode Typical Application Block Diagram VDD R TWD TWCK R Master Host with TWI Interface Host with TWI Interface Slave 1 Host with TWI Interface Slave 2 LCD Controller Slave 3 31.9.3 Programming Slave Mode The following fields must be programmed before entering Slave mode: 1. SADR (TWI_SMR): The slave device address is used in order to be accessed by master devices in read or write mode. 2. MSDIS (TWI_CR): Disable the master mode. 3. SVEN (TWI_CR): Enable the slave mode. As the device receives the clock, values written in TWI_CWGR are not taken into account. 31.9.4 Receiving Data After a Start or Repeated Start condition is detected and if the address sent by the Master matches with the Slave address programmed in the SADR (Slave ADdress) field, SVACC (Slave ACCess) flag is set and SVREAD (Slave READ) indicates the direction of the transfer. SVACC remains high until a STOP condition or a repeated START is detected. When such a condition is detected, EOSACC (End Of Slave ACCess) flag is set. 31.9.4.1 Read Sequence In the case of a Read sequence (SVREAD is high), TWI transfers data written in the TWI_THR (TWI Transmit Holding Register) until a STOP condition or a REPEATED_START + an address different from SADR is detected. Note that at the end of the read sequence TXCOMP (Transmission Complete) flag is set and SVACC reset. As soon as data is written in the TWI_THR, TXRDY (Transmit Holding Register Ready) flag is reset, and it is set when the shift register is empty and the sent data acknowledged or not. If the data is not acknowledged, the NACK flag is set. 436 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Note that a STOP or a repeated START always follows a NACK. See Figure 31-24 on page 438. 31.9.4.2 Write Sequence In the case of a Write sequence (SVREAD is low), the RXRDY (Receive Holding Register Ready) flag is set as soon as a character has been received in the TWI_RHR (TWI Receive Holding Register). RXRDY is reset when reading the TWI_RHR. TWI continues receiving data until a STOP condition or a REPEATED_START + an address different from SADR is detected. Note that at the end of the write sequence TXCOMP flag is set and SVACC reset. See Figure 31-25 on page 438. 31.9.4.3 Clock Synchronization Sequence In the case where TWI_THR or TWI_RHR is not written/read in time, TWI performs a clock synchronization. Clock stretching information is given by the SCLWS (Clock Wait state) bit. See Figure 31-27 on page 440 and Figure 31-28 on page 441. 31.9.4.4 General Call In the case where a GENERAL CALL is performed, GACC (General Call ACCess) flag is set. After GACC is set, it is up to the programmer to interpret the meaning of the GENERAL CALL and to decode the new address programming sequence. See Figure 31-26 on page 439. 31.9.4.5 PDC As it is impossible to know the exact number of data to receive/send, the use of PDC is NOT recommended in SLAVE mode. 31.9.5 31.9.5.1 Data Transfer Read Operation The read mode is defined as a data requirement from the master. After a START or a REPEATED START condition is detected, the decoding of the address starts. If the slave address (SADR) is decoded, SVACC is set and SVREAD indicates the direction of the transfer. Until a STOP or REPEATED START condition is detected, TWI continues sending data loaded in the TWI_THR register. If a STOP condition or a REPEATED START + an address different from SADR is detected, SVACC is reset. Figure 31-24 on page 438 describes the write operation. 437 6384D–ATARM–04-May-09 Figure 31-24. Read Access Ordered by a MASTER SADR does not match, TWI answers with a NACK SADR matches, TWI answers with an ACK ACK/NACK from the Master A DATA NA S/Sr TWD TXRDY NACK SVACC SVREAD EOSVACC S ADR R NA DATA NA P/S/Sr SADR R A DATA A Write THR Read RHR SVREAD has to be taken into account only while SVACC is active Notes: 1. When SVACC is low, the state of SVREAD becomes irrelevant. 2. TXRDY is reset when data has been transmitted from TWI_THR to the shift register and set when this data has been acknowledged or non acknowledged. 31.9.5.2 Write Operation The write mode is defined as a data transmission from the master. After a START or a REPEATED START, the decoding of the address starts. If the slave address is decoded, SVACC is set and SVREAD indicates the direction of the transfer (SVREAD is low in this case). Until a STOP or REPEATED START condition is detected, TWI stores the received data in the TWI_RHR register. If a STOP condition or a REPEATED START + an address different from SADR is detected, SVACC is reset. Figure 31-25 on page 438 describes the Write operation. Figure 31-25. Write Access Ordered by a Master SADR does not match, TWI answers with a NACK SADR matches, TWI answers with an ACK Read RHR TWD RXRDY SVACC SVREAD EOSVACC Notes: S ADR W NA DATA NA P/S/Sr SADR W A DATA A A DATA NA S/Sr SVREAD has to be taken into account only while SVACC is active 1. When SVACC is low, the state of SVREAD becomes irrelevant. 2. RXRDY is set when data has been transmitted from the shift register to the TWI_RHR and reset when this data is read. 438 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 31.9.5.3 General Call The general call is performed in order to change the address of the slave. If a GENERAL CALL is detected, GACC is set. After the detection of General Call, it is up to the programmer to decode the commands which come afterwards. In case of a WRITE command, the programmer has to decode the programming sequence and program a new SADR if the programming sequence matches. Figure 31-26 on page 439 describes the General Call access. Figure 31-26. Master Performs a General Call 0000000 + W RESET command = 00000110X WRITE command = 00000100X A TXD S GENERAL CALL A Reset or write DADD A DATA1 A DATA2 A New SADR P New SADR Programming sequence GCACC Reset after read SVACC Note: This method allows the user to create an own programming sequence by choosing the programming bytes and the number of them. The programming sequence has to be provided to the master. 439 6384D–ATARM–04-May-09 31.9.5.4 Clock Synchronization In both read and write modes, it may happen that TWI_THR/TWI_RHR buffer is not filled /emptied before the emission/reception of a new character. In this case, to avoid sending/receiving undesired data, a clock stretching mechanism is implemented. Clock Synchronization in Read Mode The clock is tied low if the shift register is empty and if a STOP or REPEATED START condition was not detected. It is tied low until the shift register is loaded. Figure 31-27 on page 440 describes the clock synchronization in Read mode. 31.9.5.5 Figure 31-27. Clock Synchronization in Read Mode TWI_THR DATA0 1 DATA1 DATA2 S SADR R A DATA0 A DATA1 A XXXXXXX 2 DATA2 NA S TWCK Write THR CLOCK is tied low by the TWI as long as THR is empty SCLWS TXRDY SVACC SVREAD TXCOMP As soon as a START is detected TWI_THR is transmitted to the shift register 1 2 The data is memorized in TWI_THR until a new value is written Ack or Nack from the master The clock is stretched after the ACK, the state of TWD is undefined during clock stretching Notes: 1. TXRDY is reset when data has been written in the TWI_THR to the shift register and set when this data has been acknowledged or non acknowledged. 2. At the end of the read sequence, TXCOMP is set after a STOP or after a REPEATED_START + an address different from SADR. 3. SCLWS is automatically set when the clock synchronization mechanism is started. 440 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 31.9.5.6 Clock Synchronization in Write Mode The c lock is tied lo w if the shift register and the TWI_RHR is full. If a STOP or REPEATED_START condition was not detected, it is tied low until TWI_RHR is read. Figure 31-28 on page 441 describes the clock synchronization in Read mode. Figure 31-28. Clock Synchronization in Write Mode TWCK CLOCK is tied low by the TWI as long as RHR is full TWD S SADR W A DATA0 A DATA1 A DATA2 NA S ADR TWI_RHR SCLWS DATA0 is not read in the RHR DATA1 DATA2 SCL is stretched on the last bit of DATA1 RXRDY Rd DATA0 SVACC SVREAD TXCOMP As soon as a START is detected Rd DATA1 Rd DATA2 Notes: 1. At the end of the read sequence, TXCOMP is set after a STOP or after a REPEATED_START + an address different from SADR. 2. SCLWS is automatically set when the clock synchronization mechanism is started and automatically reset when the mechanism is finished. 441 6384D–ATARM–04-May-09 31.9.5.7 31.9.5.8 Reversal after a Repeated Start Reversal of Read to Write The master initiates the communication by a read command and finishes it by a write command. Figure 31-29 on page 442 describes the repeated start + reversal from Read to Write mode. Figure 31-29. Repeated Start + Reversal from Read to Write Mode TWI_THR DATA0 DATA1 TWD S SADR R A DATA0 A DATA1 NA Sr SADR W A DATA2 A DATA3 A DATA3 P TWI_RHR SVACC SVREAD TXRDY RXRDY EOSACC TXCOMP As soon as a START is detected DATA2 Cleared after read 1. TXCOMP is only set at the end of the transmission because after the repeated start, SADR is detected again. 31.9.5.9 Reversal of Write to Read The master initiates the communication by a write command and finishes it by a read command.Figure 31-30 on page 442 describes the repeated start + reversal from Write to Read mode. Figure 31-30. Repeated Start + Reversal from Write to Read Mode TWI_THR DATA2 DATA3 TWD TWI_RHR SVACC SVREAD TXRDY RXRDY EOSACC TXCOMP S SADR W A DATA0 A DATA1 A Sr SADR R A DATA2 A DATA3 NA P DATA0 DATA1 Read TWI_RHR As soon as a START is detected Cleared after read Notes: 1. In this case, if TWI_THR has not been written at the end of the read command, the clock is automatically stretched before the ACK. 2. TXCOMP is only set at the end of the transmission because after the repeated start, SADR is detected again. 442 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 31.9.6 Read Write Flowcharts The flowchart shown in Figure 31-31 on page 443 gives an example of read and write operations in Slave mode. A polling or interrupt method can be used to check the status bits. The interrupt method requires that the interrupt enable register (TWI_IER) be configured first. Figure 31-31. Read Write Flowchart in Slave Mode Set the SLAVE mode: SADR + MSDIS + SVEN Read Status Register SVACC = 1 ? No No GACC = 1 ? No SVREAD = 0 ? No EOSACC = 1 ? TXRDY= 1 ? No No Write in TWI_THR TXCOMP = 1 ? RXRDY= 0 ? END Read TWI_RHR No GENERAL CALL TREATMENT Decoding of the programming sequence Prog seq OK ? No Change SADR 443 6384D–ATARM–04-May-09 31.10 Two-wire Interface (TWI) User Interface Table 31-4. Offset 0x00 0x04 0x08 0x0C 0x10 0x20 0x24 0x28 0x2C 0x30 0x34 0x38 - 0xFC 0x100 - 0x124 Register Mapping Register Control Register Master Mode Register Slave Mode Register Internal Address Register Clock Waveform Generator Register Status Register Interrupt Enable Register Interrupt Disable Register Interrupt Mask Register Receive Holding Register Transmit Holding Register Reserved Reserved for the PDC Name TWI_CR TWI_MMR TWI_SMR TWI_IADR TWI_CWGR TWI_SR TWI_IER TWI_IDR TWI_IMR TWI_RHR TWI_THR – – Access Write-only Read-write Read-write Read-write Read-write Read-only Write-only Write-only Read-only Read-only Write-only – – Reset N/A 0x00000000 0x00000000 0x00000000 0x00000000 0x0000F009 N/A N/A 0x00000000 0x00000000 0x00000000 – – 444 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 31.10.1 Name: Access: TWI Control Register TWI_CR Write-only Reset Value: 0x00000000 31 – 23 – 15 – 7 SWRST 30 – 22 – 14 – 6 – 29 – 21 – 13 – 5 SVDIS 28 – 20 – 12 – 4 SVEN 27 – 19 – 11 – 3 MSDIS 26 – 18 – 10 – 2 MSEN 25 – 17 – 9 – 1 STOP 24 – 16 – 8 – 0 START • START: Send a START Condition 0 = No effect. 1 = A frame beginning with a START bit is transmitted according to the features defined in the mode register. This action is necessary when the TWI peripheral wants to read data from a slave. When configured in Master Mode with a write operation, a frame is sent as soon as the user writes a character in the Transmit Holding Register (TWI_THR). • STOP: Send a STOP Condition 0 = No effect. 1 = STOP Condition is sent just after completing the current byte transmission in master read mode. – In single data byte master read, the START and STOP must both be set. – In multiple data bytes master read, the STOP must be set after the last data received but one. – In master read mode, if a NACK bit is received, the STOP is automatically performed. – In multiple data write operation, when both THR and shift register are empty, a STOP condition is automatically sent. • MSEN: TWI Master Mode Enabled 0 = No effect. 1 = If MSDIS = 0, the master mode is enabled. Note: Switching from Slave to Master mode is only permitted when TXCOMP = 1. • MSDIS: TWI Master Mode Disabled 0 = No effect. 1 = The master mode is disabled, all pending data is transmitted. The shifter and holding characters (if it contains data) are transmitted in case of write operation. In read operation, the character being transferred must be completely received before disabling. 445 6384D–ATARM–04-May-09 • SVEN: TWI Slave Mode Enabled 0 = No effect. 1 = If SVDIS = 0, the slave mode is enabled. Note: Switching from Master to Slave mode is only permitted when TXCOMP = 1. • SVDIS: TWI Slave Mode Disabled 0 = No effect. 1 = The slave mode is disabled. The shifter and holding characters (if it contains data) are transmitted in case of read operation. In write operation, the character being transferred must be completely received before disabling. • SWRST: Software Reset 0 = No effect. 1 = Equivalent to a system reset. 446 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 31.10.2 Name: Access: TWI Master Mode Register TWI_MMR Read-write Reset Value: 0x00000000 31 – 23 – 15 – 7 – 30 – 22 29 – 21 28 – 20 27 – 19 DADR 11 – 3 – 26 – 18 25 – 17 24 – 16 14 – 6 – 13 – 5 – 12 MREAD 4 – 10 – 2 – 9 IADRSZ 1 – 8 0 – • IADRSZ: Internal Device Address Size IADRSZ[9:8] 0 0 1 1 0 1 0 1 No internal device address One-byte internal device address Two-byte internal device address Three-byte internal device address • MREAD: Master Read Direction 0 = Master write direction. 1 = Master read direction. • DADR: Device Address The device address is used to access slave devices in read or write mode. Those bits are only used in Master mode. 447 6384D–ATARM–04-May-09 31.10.3 Name: Access: TWI Slave Mode Register TWI_SMR Read-write Reset Value: 0x00000000 31 – 23 – 15 – 7 – 30 – 22 29 – 21 28 – 20 27 – 19 SADR 11 – 3 – 26 – 18 25 – 17 24 – 16 14 – 6 – 13 – 5 – 12 – 4 – 10 – 2 – 9 8 1 – 0 – • SADR: Slave Address The slave device address is used in Slave mode in order to be accessed by master devices in read or write mode. SADR must be programmed before enabling the Slave mode or after a general call. Writes at other times have no effect. 31.10.4 Name: Access: TWI Internal Address Register TWI_IADR Read-write Reset Value: 0x00000000 31 – 23 30 – 22 29 – 21 28 – 20 IADR 15 14 13 12 IADR 7 6 5 4 IADR 3 2 1 0 11 10 9 8 27 – 19 26 – 18 25 – 17 24 – 16 • IADR: Internal Address 0, 1, 2 or 3 bytes depending on IADRSZ. 448 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 31.10.5 Name: Access: TWI Clock Waveform Generator Register TWI_CWGR Read-write Reset Value: 0x00000000 31 – 23 30 – 22 29 – 21 28 – 20 27 – 19 26 – 18 25 – 17 CKDIV 9 24 – 16 15 14 13 12 CHDIV 11 10 8 7 6 5 4 CLDIV 3 2 1 0 TWI_CWGR is only used in Master mode. • CLDIV: Clock Low Divider The SCL low period is defined as follows: T low = ( ( CLDIV × 2 CKDIV ) + 4 ) × T MCK • CHDIV: Clock High Divider The SCL high period is defined as follows: T high = ( ( CHDIV × 2 CKDIV ) + 4 ) × T MCK • CKDIV: Clock Divider The CKDIV is used to increase both SCL high and low periods. 449 6384D–ATARM–04-May-09 31.10.6 Name: Access: TWI Status Register TWI_SR Read-only Reset Value: 0x0000F009 31 – 23 – 15 TXBUFE 7 – 30 – 22 – 14 RXBUFF 6 OVRE 29 – 21 – 13 ENDTX 5 GACC 28 – 20 – 12 ENDRX 4 SVACC 27 – 19 – 11 EOSACC 3 SVREAD 26 – 18 – 10 SCLWS 2 TXRDY 25 – 17 – 9 ARBLST 1 RXRDY 24 – 16 – 8 NACK 0 TXCOMP • TXCOMP: Transmission Completed (automatically set / reset) TXCOMP used in Master mode: 0 = During the length of the current frame. 1 = When both holding and shifter registers are empty and STOP condition has been sent. TXCOMP behavior in Master mode can be seen in Figure 31-7 on page 422 and in Figure 31-10 on page 423. TXCOMP used in Slave mode: 0 = As soon as a Start is detected. 1 = After a Stop or a Repeated Start + an address different from SADR is detected. TXCOMP behavior in Slave mode can be seen in Figure 31-27 on page 440, Figure 31-28 on page 441, Figure 31-29 on page 442 and Figure 31-30 on page 442. • RXRDY: Receive Holding Register Ready (automatically set / reset) 0 = No character has been received since the last TWI_RHR read operation. 1 = A byte has been received in the TWI_RHR since the last read. RXRDY behavior in Master mode can be seen in Figure 31-10 on page 423. RXRDY behavior in Slave mode can be seen in Figure 31-25 on page 438, Figure 31-28 on page 441, Figure 31-29 on page 442 and Figure 31-30 on page 442. • TXRDY: Transmit Holding Register Ready (automatically set / reset) TXRDY used in Master mode: 0 = The transmit holding register has not been transferred into shift register. Set to 0 when writing into TWI_THR register. 1 = As soon as a data byte is transferred from TWI_THR to internal shifter or if a NACK error is detected, TXRDY is set at the same time as TXCOMP and NACK. TXRDY is also set when MSEN is set (enable TWI). TXRDY behavior in Master mode can be seen in Figure 31-8 on page 422. 450 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary TXRDY used in Slave mode: 0 = As soon as data is written in the TWI_THR, until this data has been transmitted and acknowledged (ACK or NACK). 1 = It indicates that the TWI_THR is empty and that data has been transmitted and acknowledged. If TXRDY is high and if a NACK has been detected, the transmission will be stopped. Thus when TRDY = NACK = 1, the programmer must not fill TWI_THR to avoid losing it. TXRDY behavior in Slave mode can be seen in Figure 31-24 on page 438, Figure 31-27 on page 440, Figure 31-29 on page 442 and Figure 31-30 on page 442. • SVREAD: Slave Read (automatically set / reset) This bit is only used in Slave mode. When SVACC is low (no Slave access has been detected) SVREAD is irrelevant. 0 = Indicates that a write access is performed by a Master. 1 = Indicates that a read access is performed by a Master. SVREAD behavior can be seen in Figure 31-24 on page 438, Figure 31-25 on page 438, Figure 31-29 on page 442 and Figure 31-30 on page 442. • SVACC: Slave Access (automatically set / reset) This bit is only used in Slave mode. 0 = TWI is not addressed. SVACC is automatically cleared after a NACK or a STOP condition is detected. 1 = Indicates that the address decoding sequence has matched (A Master has sent SADR). SVACC remains high until a NACK or a STOP condition is detected. SVACC behavior can be seen in Figure 31-24 on page 438, Figure 31-25 on page 438, Figure 31-29 on page 442 and Figure 31-30 on page 442. • GACC: General Call Access (clear on read) This bit is only used in Slave mode. 0 = No General Call has been detected. 1 = A General Call has been detected. After the detection of General Call, the programmer decoded the commands that follow and the programming sequence. GACC behavior can be seen in Figure 31-26 on page 439. • OVRE: Overrun Error (clear on read) This bit is only used in Master mode. 0 = TWI_RHR has not been loaded while RXRDY was set 1 = TWI_RHR has been loaded while RXRDY was set. Reset by read in TWI_SR when TXCOMP is set. • NACK: Not Acknowledged (clear on read) NACK used in Master mode: 0 = Each data byte has been correctly received by the far-end side TWI slave component. 1 = A data byte has not been acknowledged by the slave component. Set at the same time as TXCOMP. 451 6384D–ATARM–04-May-09 NACK used in Slave Read mode: 0 = Each data byte has been correctly received by the Master. 1 = In read mode, a data byte has not been acknowledged by the Master. When NACK is set the programmer must not fill TWI_THR even if TXRDY is set, because it means that the Master will stop the data transfer or re initiate it. Note that in Slave Write mode all data are acknowledged by the TWI. • ARBLST: Arbitration Lost (clear on read) This bit is only used in Master mode. 0: Arbitration won. 1: Arbitration lost. Another master of the TWI bus has won the multi-master arbitration. TXCOMP is set at the same time. • SCLWS: Clock Wait State (automatically set / reset) This bit is only used in Slave mode. 0 = The clock is not stretched. 1 = The clock is stretched. TWI_THR / TWI_RHR buffer is not filled / emptied before the emission / reception of a new character. SCLWS behavior can be seen in Figure 31-27 on page 440 and Figure 31-28 on page 441. • EOSACC: End Of Slave Access (clear on read) This bit is only used in Slave mode. 0 = A slave access is being performing. 1 = The Slave Access is finished. End Of Slave Access is automatically set as soon as SVACC is reset. EOSACC behavior can be seen in Figure 31-29 on page 442 and Figure 31-30 on page 442 • ENDRX: End of RX buffer This bit is only used in Master mode. 0 = The Receive Counter Register has not reached 0 since the last write in TWI_RCR or TWI_RNCR. 1 = The Receive Counter Register has reached 0 since the last write in TWI_RCR or TWI_RNCR. • ENDTX: End of TX buffer This bit is only used in Master mode. 0 = The Transmit Counter Register has not reached 0 since the last write in TWI_TCR or TWI_TNCR. 1 = The Transmit Counter Register has reached 0 since the last write in TWI_TCR or TWI_TNCR. • RXBUFF: RX Buffer Full This bit is only used in Master mode. 0 = TWI_RCR or TWI_RNCR have a value other than 0. 1 = Both TWI_RCR and TWI_RNCR have a value of 0. 452 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary • TXBUFE: TX Buffer Empty This bit is only used in Master mode. 0 = TWI_TCR or TWI_TNCR have a value other than 0. 1 = Both TWI_TCR and TWI_TNCR have a value of 0. 453 6384D–ATARM–04-May-09 31.10.7 Name: Access: TWI Interrupt Enable Register TWI_IER Write-only Reset Value: 0x00000000 31 – 23 – 15 TXBUFE 7 – 30 – 22 – 14 RXBUFF 6 OVRE 29 – 21 – 13 ENDTX 5 GACC 28 – 20 – 12 ENDRX 4 SVACC 27 – 19 – 11 EOSACC 3 – 26 – 18 – 10 SCL_WS 2 TXRDY 25 – 17 – 9 ARBLST 1 RXRDY 24 – 16 – 8 NACK 0 TXCOMP • TXCOMP: Transmission Completed Interrupt Enable • RXRDY: Receive Holding Register Ready Interrupt Enable • TXRDY: Transmit Holding Register Ready Interrupt Enable • SVACC: Slave Access Interrupt Enable • GACC: General Call Access Interrupt Enable • OVRE: Overrun Error Interrupt Enable • NACK: Not Acknowledge Interrupt Enable • ARBLST: Arbitration Lost Interrupt Enable • SCL_WS: Clock Wait State Interrupt Enable • EOSACC: End Of Slave Access Interrupt Enable • ENDRX: End of Receive Buffer Interrupt Enable • ENDTX: End of Transmit Buffer Interrupt Enable • RXBUFF: Receive Buffer Full Interrupt Enable • TXBUFE: Transmit Buffer Empty Interrupt Enable 0 = No effect. 1 = Enables the corresponding interrupt. 454 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 31.10.8 Name: Access: TWI Interrupt Disable Register TWI_IDR Write-only Reset Value: 0x00000000 31 – 23 – 15 TXBUFE 7 – 30 – 22 – 14 RXBUFF 6 OVRE 29 – 21 – 13 ENDTX 5 GACC 28 – 20 – 12 ENDRX 4 SVACC 27 – 19 – 11 EOSACC 3 – 26 – 18 – 10 SCL_WS 2 TXRDY 25 – 17 – 9 ARBLST 1 RXRDY 24 – 16 – 8 NACK 0 TXCOMP • TXCOMP: Transmission Completed Interrupt Disable • RXRDY: Receive Holding Register Ready Interrupt Disable • TXRDY: Transmit Holding Register Ready Interrupt Disable • SVACC: Slave Access Interrupt Disable • GACC: General Call Access Interrupt Disable • OVRE: Overrun Error Interrupt Disable • NACK: Not Acknowledge Interrupt Disable • ARBLST: Arbitration Lost Interrupt Disable • SCL_WS: Clock Wait State Interrupt Disable • EOSACC: End Of Slave Access Interrupt Disable • ENDRX: End of Receive Buffer Interrupt Disable • ENDTX: End of Transmit Buffer Interrupt Disable • RXBUFF: Receive Buffer Full Interrupt Disable • TXBUFE: Transmit Buffer Empty Interrupt Disable 0 = No effect. 1 = Disables the corresponding interrupt. 455 6384D–ATARM–04-May-09 31.10.9 Name: Access: TWI Interrupt Mask Register TWI_IMR Read-only Reset Value: 0x00000000 31 – 23 – 15 TXBUFE 7 – 30 – 22 – 14 RXBUFF 6 OVRE 29 – 21 – 13 ENDTX 5 GACC 28 – 20 – 12 ENDRX 4 SVACC 27 – 19 – 11 EOSACC 3 – 26 – 18 – 10 SCL_WS 2 TXRDY 25 – 17 – 9 ARBLST 1 RXRDY 24 – 16 – 8 NACK 0 TXCOMP • TXCOMP: Transmission Completed Interrupt Mask • RXRDY: Receive Holding Register Ready Interrupt Mask • TXRDY: Transmit Holding Register Ready Interrupt Mask • SVACC: Slave Access Interrupt Mask • GACC: General Call Access Interrupt Mask • OVRE: Overrun Error Interrupt Mask • NACK: Not Acknowledge Interrupt Mask • ARBLST: Arbitration Lost Interrupt Mask • SCL_WS: Clock Wait State Interrupt Mask • EOSACC: End Of Slave Access Interrupt Mask • ENDRX: End of Receive Buffer Interrupt Mask • ENDTX: End of Transmit Buffer Interrupt Mask • RXBUFF: Receive Buffer Full Interrupt Mask • TXBUFE: Transmit Buffer Empty Interrupt Mask 0 = The corresponding interrupt is disabled. 1 = The corresponding interrupt is enabled. 456 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 31.10.10 TWI Receive Holding Register Name: TWI_RHR Access: Read-only Reset Value: 0x00000000 31 – 23 – 15 – 7 30 – 22 – 14 – 6 29 – 21 – 13 – 5 28 – 20 – 12 – 4 RXDATA 27 – 19 – 11 – 3 26 – 18 – 10 – 2 25 – 17 – 9 – 1 24 – 16 – 8 – 0 • RXDATA: Master or Slave Receive Holding Data 457 6384D–ATARM–04-May-09 31.10.11 TWI Transmit Holding Register Name: TWI_THR Access: Read-write Reset Value: 0x00000000 31 – 23 – 15 – 7 30 – 22 – 14 – 6 29 – 21 – 13 – 5 28 – 20 – 12 – 4 TXDATA 27 – 19 – 11 – 3 26 – 18 – 10 – 2 25 – 17 – 9 – 1 24 – 16 – 8 – 0 • TXDATA: Master or Slave Transmit Holding Data 458 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 32. Universal Synchronous Asynchronous Receiver Transmitter (USART) 32.1 Overview The Universal Synchronous Asynchronous Receiver Transceiver (USART) provides one full duplex universal synchronous asynchronous serial link. Data frame format is widely programmable (data length, parity, number of stop bits) to support a maximum of standards. The receiver implements parity error, framing error and overrun error detection. The receiver time-out enables handling variable-length frames and the transmitter timeguard facilitates communications with slow remote devices. Multidrop communications are also supported through address bit handling in reception and transmission. The USART features three test modes: remote loopback, local loopback and automatic echo. The USART supports specific operating modes providing interfaces on RS485 buses, with ISO7816 T = 0 or T = 1 smart card slots, infrared transceivers and connection to modem ports. The hardware handshaking feature enables an out-of-band flow control by automatic management of the pins RTS and CTS. The USART supports the connection to the Peripheral DMA Controller, which enables data transfers to the transmitter and from the receiver. The PDC provides chained buffer management without any intervention of the processor. 459 6384D–ATARM–04-May-09 32.2 Block Diagram Figure 32-1. USART Block Diagram Peripheral DMA Controller Channel Channel USART PIO Controller RXD Receiver RTS AIC USART Interrupt TXD Transmitter CTS DTR PMC MCK MCK/DIV Modem Signals Control DSR DCD RI SLCK Baud Rate Generator SCK DIV User Interface APB 460 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 32.3 Application Block Diagram Figure 32-2. Application Block Diagram PPP Modem Driver Serial Driver Field Bus Driver EMV Driver IrLAP IrDA Driver USART RS232 Drivers Modem PSTN RS232 Drivers RS485 Drivers Smart Card Slot IrDA Transceivers Serial Port Differential Bus 461 6384D–ATARM–04-May-09 32.4 I/O Lines Description I/O Line Description Description Serial Clock Transmit Serial Data Receive Serial Data Ring Indicator Data Set Ready Data Carrier Detect Data Terminal Ready Clear to Send Request to Send Type I/O I/O Input Input Input Input Output Input Output Low Low Low Low Low Low Active Level Table 32-1. Name SCK TXD RXD RI DSR DCD DTR CTS RTS 462 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 32.5 32.5.1 Product Dependencies I/O Lines The pins used for interfacing the USART may be multiplexed with the PIO lines. The programmer must first program the PIO controller to assign the desired USART pins to their peripheral function. If I/O lines of the USART are not used by the application, they can be used for other purposes by the PIO Controller. To prevent the TXD line from falling when the USART is disabled, the use of an internal pull up is mandatory. If the hardware handshaking feature or Modem mode is used, the internal pull up on TXD must also be enabled. All the pins of the modems may or may not be implemented on the USART. Only USART0 is fully equipped with all the modem signals. On USARTs not equipped with the corresponding pin, the associated control bits and statuses have no effect on the behavior of the USART. 32.5.2 Power Management The USART is not continuously clocked. The programmer must first enable the USART Clock in the Power Management Controller (PMC) before using the USART. However, if the application does not require USART operations, the USART clock can be stopped when not needed and be restarted later. In this case, the USART will resume its operations where it left off. Configuring the USART does not require the USART clock to be enabled. 32.5.3 Interrupt The USART interrupt line is connected on one of the internal sources of the Advanced Interrupt Controller. Using the USART interrupt requires the AIC to be programmed first. Note that it is not recommended to use the USART interrupt line in edge sensitive mode. 463 6384D–ATARM–04-May-09 32.6 Functional Description The USART is capable of managing several types of serial synchronous or asynchronous communications. It supports the following communication modes: • 5- to 9-bit full-duplex asynchronous serial communication – MSB- or LSB-first – 1, 1.5 or 2 stop bits – Parity even, odd, marked, space or none – By 8 or by 16 over-sampling receiver frequency – Optional hardware handshaking – Optional modem signals management – Optional break management – Optional multidrop serial communication • High-speed 5- to 9-bit full-duplex synchronous serial communication – MSB- or LSB-first – 1 or 2 stop bits – Parity even, odd, marked, space or none – By 8 or by 16 over-sampling frequency – Optional hardware handshaking – Optional modem signals management – Optional break management – Optional multidrop serial communication • RS485 with driver control signal • ISO7816, T0 or T1 protocols for interfacing with smart cards – NACK handling, error counter with repetition and iteration limit • InfraRed IrDA Modulation and Demodulation • Test modes – Remote loopback, local loopback, automatic echo 32.6.1 Baud Rate Generator The Baud Rate Generator provides the bit period clock named the Baud Rate Clock to both the receiver and the transmitter. The Baud Rate Generator clock source can be selected by setting the USCLKS field in the Mode Register (US_MR) between: • the Master Clock MCK • a division of the Master Clock, the divider being product dependent, but generally set to 8 • the external clock, available on the SCK pin The Baud Rate Generator is based upon a 16-bit divider, which is programmed with the CD field of the Baud Rate Generator Register (US_BRGR). If CD is programmed at 0, the Baud Rate Generator does not generate any clock. If CD is programmed at 1, the divider is bypassed and becomes inactive. 464 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary If the external SCK clock is selected, the duration of the low and high levels of the signal provided on the SCK pin must be longer than a Master Clock (MCK) period. The frequency of the signal provided on SCK must be at least 4.5 times lower than MCK. Figure 32-3. Baud Rate Generator USCLKS MCK MCK/DIV SCK Reserved CD CD 0 1 2 3 0 16-bit Counter >1 1 0 1 1 SYNC USCLKS = 3 Sampling Clock 0 OVER Sampling Divider 0 Baud Rate Clock FIDI SYNC SCK 32.6.1.1 Baud Rate in Asynchronous Mode If the USART is programmed to operate in asynchronous mode, the selected clock is first divided by CD, which is field programmed in the Baud Rate Generator Register (US_BRGR). The resulting clock is provided to the receiver as a sampling clock and then divided by 16 or 8, depending on the programming of the OVER bit in US_MR. If OVER is set to 1, the receiver sampling is 8 times higher than the baud rate clock. If OVER is cleared, the sampling is performed at 16 times the baud rate clock. The following formula performs the calculation of the Baud Rate. SelectedClock Baudrate = -------------------------------------------( 8 ( 2 – Over ) CD ) This gives a maximum baud rate of MCK divided by 8, assuming that MCK is the highest possible clock and that OVER is programmed at 1. 32.6.1.2 Baud Rate Calculation Example Table 32-2 shows calculations of CD to obtain a baud rate at 38400 bauds for different source clock frequencies. This table also shows the actual resulting baud rate and the error. Baud Rate Example (OVER = 0) Expected Baud Rate Bit/s 38 400 38 400 38 400 38 400 6.00 8.00 8.14 12.00 6 8 8 12 Calculation Result CD Actual Baud Rate Bit/s 38 400.00 38 400.00 39 062.50 38 400.00 0.00% 0.00% 1.70% 0.00% Error Table 32-2. Source Clock MHz 3 686 400 4 915 200 5 000 000 7 372 800 465 6384D–ATARM–04-May-09 Table 32-2. Baud Rate Example (OVER = 0) (Continued) Expected Baud Rate 38 400 38 400 38 400 38 400 38 400 38 400 38 400 38 400 38 400 38 400 38 400 38 400 38 400 38 400 Calculation Result 13.02 19.53 20.00 23.30 24.00 30.00 39.06 40.00 40.69 52.08 53.33 53.71 65.10 81.38 CD 13 20 20 23 24 30 39 40 40 52 53 54 65 81 Actual Baud Rate 38 461.54 37 500.00 38 400.00 38 908.10 38 400.00 38 400.00 38 461.54 38 400.00 38 109.76 38 461.54 38 641.51 38 194.44 38 461.54 38 580.25 Error 0.16% 2.40% 0.00% 1.31% 0.00% 0.00% 0.16% 0.00% 0.76% 0.16% 0.63% 0.54% 0.16% 0.47% Source Clock 8 000 000 12 000 000 12 288 000 14 318 180 14 745 600 18 432 000 24 000 000 24 576 000 25 000 000 32 000 000 32 768 000 33 000 000 40 000 000 50 000 000 The baud rate is calculated with the following formula: BaudRate = MCK ⁄ CD × 16 The baud rate error is calculated with the following formula. It is not recommended to work with an error higher than 5%. ExpectedBaudRate Error = 1 – ⎛ --------------------------------------------------⎞ ⎝ ActualBaudRate ⎠ 32.6.1.3 Fractional Baud Rate in Asynchronous Mode The Baud Rate generator previously defined is subject to the following limitation: the output frequency changes by only integer multiples of the reference frequency. An approach to this problem is to integrate a fractional N clock generator that has a high resolution. The generator architecture is modified to obtain Baud Rate changes by a fraction of the reference source clock. This fractional part is programmed with the FP field in the Baud Rate Generator Register (US_BRGR). If FP is not 0, the fractional part is activated. The resolution is one eighth of the clock divider. This feature is only available when using USART normal mode. The fractional Baud Rate is calculated using the following formula: SelectedClock Baudrate = ---------------------------------------------------------------⎛ 8 ( 2 – Over ) ⎛ CD + FP⎞ ⎞ -----⎝ ⎝ 8 ⎠⎠ The modified architecture is presented below: 466 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Figure 32-4. Fractional Baud Rate Generator FP USCLKS MCK MCK/DIV SCK Reserved CD Modulus Control FP CD SCK FIDI 0 OVER Sampling Divider 1 1 SYNC USCLKS = 3 Sampling Clock 0 Baud Rate Clock SYNC 0 1 2 3 16-bit Counter glitch-free logic >1 1 0 0 32.6.1.4 Baud Rate in Synchronous Mode If the USART is programmed to operate in synchronous mode, the selected clock is simply divided by the field CD in US_BRGR. BaudRate = SelectedClock ------------------------------------CD In synchronous mode, if the external clock is selected (USCLKS = 3), the clock is provided directly by the signal on the USART SCK pin. No division is active. The value written in US_BRGR has no effect. The external clock frequency must be at least 4.5 times lower than the system clock. When either the external clock SCK or the internal clock divided (MCK/DIV) is selected, the value programmed in CD must be even if the user has to ensure a 50:50 mark/space ratio on the SCK pin. If the internal clock MCK is selected, the Baud Rate Generator ensures a 50:50 duty cycle on the SCK pin, even if the value programmed in CD is odd. 32.6.1.5 Baud Rate in ISO 7816 Mode The ISO7816 specification defines the bit rate with the following formula: Di B = ----- × f Fi where: • B is the bit rate • Di is the bit-rate adjustment factor • Fi is the clock frequency division factor • f is the ISO7816 clock frequency (Hz) 467 6384D–ATARM–04-May-09 Di is a binary value encoded on a 4-bit field, named DI, as represented in Table 32-3. Table 32-3. DI field Di (decimal) Binary and Decimal Values for Di 0001 1 0010 2 0011 4 0100 8 0101 16 0110 32 1000 12 1001 20 Fi is a binary value encoded on a 4-bit field, named FI, as represented in Table 32-4. Table 32-4. FI field Fi (decimal Binary and Decimal Values for Fi 0000 372 0001 372 0010 558 0011 744 0100 1116 0101 1488 0110 1860 1001 512 1010 768 1011 1024 1100 1536 1101 2048 Table 32-5 shows the resulting Fi/Di Ratio, which is the ratio between the ISO7816 clock and the baud rate clock. Table 32-5. Fi/Di 1 2 4 8 16 32 12 20 Possible Values for the Fi/Di Ratio 372 372 186 93 46.5 23.25 11.62 31 18.6 558 558 279 139.5 69.75 34.87 17.43 46.5 27.9 774 744 372 186 93 46.5 23.25 62 37.2 1116 1116 558 279 139.5 69.75 34.87 93 55.8 1488 1488 744 372 186 93 46.5 124 74.4 1806 1860 930 465 232.5 116.2 58.13 155 93 512 512 256 128 64 32 16 42.66 25.6 768 768 384 192 96 48 24 64 38.4 1024 1024 512 256 128 64 32 85.33 51.2 1536 1536 768 384 192 96 48 128 76.8 2048 2048 1024 512 256 128 64 170.6 102.4 If the USART is configured in ISO7816 Mode, the clock selected by the USCLKS field in the Mode Register (US_MR) is first divided by the value programmed in the field CD in the Baud Rate Generator Register (US_BRGR). The resulting clock can be provided to the SCK pin to feed the smart card clock inputs. This means that the CLKO bit can be set in US_MR. This clock is then divided by the value programmed in the FI_DI_RATIO field in the FI_DI_Ratio register (US_FIDI). This is performed by the Sampling Divider, which performs a division by up to 2047 in ISO7816 Mode. The non-integer values of the Fi/Di Ratio are not supported and the user must program the FI_DI_RATIO field to a value as close as possible to the expected value. The FI_DI_RATIO field resets to the value 0x174 (372 in decimal) and is the most common divider between the ISO7816 clock and the bit rate (Fi = 372, Di = 1). Figure 32-5 shows the relation between the Elementary Time Unit, corresponding to a bit time, and the ISO 7816 clock. 468 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Figure 32-5. Elementary Time Unit (ETU) FI_DI_RATIO ISO7816 Clock Cycles ISO7816 Clock on SCK ISO7816 I/O Line on TXD 1 ETU 32.6.2 Receiver and Transmitter Control After reset, the receiver is disabled. The user must enable the receiver by setting the RXEN bit in the Control Register (US_CR). However, the receiver registers can be programmed before the receiver clock is enabled. After reset, the transmitter is disabled. The user must enable it by setting the TXEN bit in the Control Register (US_CR). However, the transmitter registers can be programmed before being enabled. The Receiver and the Transmitter can be enabled together or independently. At any time, the software can perform a reset on the receiver or the transmitter of the USART by setting the corresponding bit, RSTRX and RSTTX respectively, in the Control Register (US_CR). The software resets clear the status flag and reset internal state machines but the user interface configuration registers hold the value configured prior to software reset. Regardless of what the receiver or the transmitter is performing, the communication is immediately stopped. The user can also independently disable the receiver or the transmitter by setting RXDIS and TXDIS respectively in US_CR. If the receiver is disabled during a character reception, the USART waits until the end of reception of the current character, then the reception is stopped. If the transmitter is disabled while it is operating, the USART waits the end of transmission of both the current character and character being stored in the Transmit Holding Register (US_THR). If a timeguard is programmed, it is handled normally. 32.6.3 32.6.3.1 Synchronous and Asynchronous Modes Transmitter Operations The transmitter performs the same in both synchronous and asynchronous operating modes (SYNC = 0 or SYNC = 1). One start bit, up to 9 data bits, one optional parity bit and up to two stop bits are successively shifted out on the TXD pin at each falling edge of the programmed serial clock. The number of data bits is selected by the CHRL field and the MODE 9 bit in the Mode Register (US_MR). Nine bits are selected by setting the MODE 9 bit regardless of the CHRL field. The parity bit is set according to the PAR field in US_MR. The even, odd, space, marked or none parity bit can be configured. The MSBF field in US_MR configures which data bit is sent first. If written at 1, the most significant bit is sent first. At 0, the less significant bit is sent first. The number of stop bits is selected by the NBSTOP field in US_MR. The 1.5 stop bit is supported in asynchronous mode only. 469 6384D–ATARM–04-May-09 Figure 32-6. Character Transmit Example: 8-bit, Parity Enabled One Stop Baud Rate Clock TXD Start Bit D0 D1 D2 D3 D4 D5 D6 D7 Parity Bit Stop Bit The characters are sent by writing in the Transmit Holding Register (US_THR). The transmitter reports two status bits in the Channel Status Register (US_CSR): TXRDY (Transmitter Ready), which indicates that US_THR is empty and TXEMPTY, which indicates that all the characters written in US_THR have been processed. When the current character processing is completed, the last character written in US_THR is transferred into the Shift Register of the transmitter and US_THR becomes empty, thus TXRDY rises. Both TXRDY and TXEMPTY bits are low when the transmitter is disabled. Writing a character in US_THR while TXRDY is low has no effect and the written character is lost. Figure 32-7. Transmitter Status Baud Rate Clock TXD Start D0 Bit D1 D2 D3 D4 D5 D6 D7 Parity Stop Start D0 Bit Bit Bit D1 D2 D3 D4 D5 D6 D7 Parity Stop Bit Bit Write US_THR TXRDY TXEMPTY 32.6.3.2 Manchester Encoder When the Manchester encoder is in use, characters transmitted through the USART are encoded based on biphase Manchester II format. To enable this mode, set the MAN field in the US_MR register to 1. Depending on polarity configuration, a logic level (zero or one), is transmitted as a coded signal one-to-zero or zero-to-one. Thus, a transition always occurs at the midpoint of each bit time. It consumes more bandwidth than the original NRZ signal (2x) but the receiver has more error control since the expected input must show a change at the center of a bit cell. An example of Manchester encoded sequence is: the byte 0xB1 or 10110001 encodes to 10 01 10 10 01 01 01 10, assuming the default polarity of the encoder. Figure 32-8 illustrates this coding scheme. 470 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Figure 32-8. NRZ to Manchester Encoding NRZ encoded data Manchester encoded data 1 0 1 1 0 0 0 1 Txd The Manchester encoded character can also be encapsulated by adding both a configurable preamble and a start frame delimiter pattern. Depending on the configuration, the preamble is a training sequence, composed of a pre-defined pattern with a programmable length from 1 to 15 bit times. If the preamble length is set to 0, the preamble waveform is not generated prior to any character. The preamble pattern is chosen among the following sequences: ALL_ONE, ALL_ZERO, ONE_ZERO or ZERO_ONE, writing the field TX_PP in the US_MAN register, the field TX_PL is used to configure the preamble length. Figure 32-9 illustrates and defines the valid patterns. To improve flexibility, the encoding scheme can be configured using the TX_MPOL field in the US_MAN register. If the TX_MPOL field is set to zero (default), a logic zero is encoded with a zero-to-one transition and a logic one is encoded with a one-to-zero transition. If the TX_MPOL field is set to one, a logic one is encoded with a one-to-zero transition and a logic zero is encoded with a zero-to-one transition. Figure 32-9. Preamble Patterns, Default Polarity Assumed Manchester encoded data Txd SFD DATA 8 bit width "ALL_ONE" Preamble Manchester encoded data Txd SFD DATA 8 bit width "ALL_ZERO" Preamble Manchester encoded data Txd SFD DATA 8 bit width "ZERO_ONE" Preamble Manchester encoded data Txd SFD DATA 8 bit width "ONE_ZERO" Preamble A start frame delimiter is to be configured using the ONEBIT field in the US_MR register. It consists of a user-defined pattern that indicates the beginning of a valid data. Figure 32-10 illustrates these patterns. If the start frame delimiter, also known as start bit, is one bit, (ONEBIT at 1), a logic zero is Manchester encoded and indicates that a new character is being sent serially on the line. If the start frame delimiter is a synchronization pattern also referred to as sync (ONEBIT at 0), a sequence of 3 bit times is sent serially on the line to indicate the start of a new 471 6384D–ATARM–04-May-09 character. The sync waveform is in itself an invalid Manchester waveform as the transition occurs at the middle of the second bit time. Two distinct sync patterns are used: the command sync and the data sync. The command sync has a logic one level for one and a half bit times, then a transition to logic zero for the second one and a half bit times. If the MODSYNC field in the US_MR register is set to 1, the next character is a command. If it is set to 0, the next character is a data. When direct memory access is used, the MODSYNC field can be immediately updated with a modified character located in memory. To enable this mode, VAR_SYNC field in US_MR register must be set to 1. In this case, the MODSYNC field in US_MR is bypassed and the sync configuration is held in the TXSYNH in the US_THR register. The USART character format is modified and includes sync information. Figure 32-10. Start Frame Delimiter Preamble Length is set to 0 SFD Manchester encoded data Txd DATA One bit start frame delimiter SFD Manchester encoded data Txd DATA SFD Manchester encoded data Txd Command Sync start frame delimiter DATA Data Sync start frame delimiter 32.6.3.3 Drift Compensation Drift compensation is available only in 16X oversampling mode. An hardware recovery system allows a larger clock drift. To enable the hardware system, the bit in the USART_MAN register must be set. If the RXD edge is one 16X clock cycle from the expected edge, this is considered as normal jitter and no corrective actions is taken. If the RXD event is between 4 and 2 clock cycles before the expected edge, then the current period is shortened by one clock cycle. If the RXD event is between 2 and 3 clock cycles after the expected edge, then the current period is lengthened by one clock cycle. These intervals are considered to be drift and so corrective actions are automatically taken. 472 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Figure 32-11. Bit Resynchronization Oversampling 16x Clock RXD Sampling point Expected edge Synchro. Error Synchro. Jump Tolerance Sync Jump Synchro. Error 32.6.3.4 Asynchronous Receiver If the USART is programmed in asynchronous operating mode (SYNC = 0), the receiver oversamples the RXD input line. The oversampling is either 16 or 8 times the Baud Rate clock, depending on the OVER bit in the Mode Register (US_MR). The receiver samples the RXD line. If the line is sampled during one half of a bit time at 0, a start bit is detected and data, parity and stop bits are successively sampled on the bit rate clock. If the oversampling is 16, (OVER at 0), a start is detected at the eighth sample at 0. Then, data bits, parity bit and stop bit are sampled on each 16 sampling clock cycle. If the oversampling is 8 (OVER at 1), a start bit is detected at the fourth sample at 0. Then, data bits, parity bit and stop bit are sampled on each 8 sampling clock cycle. The number of data bits, first bit sent and parity mode are selected by the same fields and bits as the transmitter, i.e. respectively CHRL, MODE9, MSBF and PAR. For the synchronization mechanism only, the number of stop bits has no effect on the receiver as it considers only one stop bit, regardless of the field NBSTOP, so that resynchronization between the receiver and the transmitter can occur. Moreover, as soon as the stop bit is sampled, the receiver starts looking for a new start bit so that resynchronization can also be accomplished when the transmitter is operating with one stop bit. Figure 32-12 and Figure 32-13 illustrate start detection and character reception when USART operates in asynchronous mode. 473 6384D–ATARM–04-May-09 Figure 32-12. Asynchronous Start Detection Baud Rate Clock Sampling Clock (x16) RXD Sampling 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 D0 Sampling Start Detection RXD Sampling 1 2 3 4 5 6 01 Start Rejection 7 2 3 4 Figure 32-13. Asynchronous Character Reception Example: 8-bit, Parity Enabled Baud Rate Clock RXD Start Detection 16 16 16 16 16 16 16 16 16 16 samples samples samples samples samples samples samples samples samples samples D0 D1 D2 D3 D4 D5 D6 D7 Parity Bit Stop Bit 32.6.3.5 Manchester Decoder When the MAN field in US_MR register is set to 1, the Manchester decoder is enabled. The decoder performs both preamble and start frame delimiter detection. One input line is dedicated to Manchester encoded input data. An optional preamble sequence can be defined, its length is user-defined and totally independent of the emitter side. Use RX_PL in US_MAN register to configure the length of the preamble sequence. If the length is set to 0, no preamble is detected and the function is disabled. In addition, the polarity of the input stream is programmable with RX_MPOL field in US_MAN register. Depending on the desired application the preamble pattern matching is to be defined via the RX_PP field in US_MAN. See Figure 32-9 for available preamble patterns. Unlike preamble, the start frame delimiter is shared between Manchester Encoder and Decoder. So, if ONEBIT field is set to 1, only a zero encoded Manchester can be detected as a valid start frame delimiter. If ONEBIT is set to 0, only a sync pattern is detected as a valid start frame delimiter. Decoder operates by detecting transition on incoming stream. If RXD is sampled during one quarter of a bit time at zero, a start bit is detected. See Figure 32-14.. The sample pulse rejection mechanism applies. 474 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Figure 32-14. Asynchronous Start Bit Detection Sampling Clock (16 x) Manchester encoded data Txd Start Detection 1 2 3 4 The receiver is activated and starts Preamble and Frame Delimiter detection, sampling the data at one quarter and then three quarters. If a valid preamble pattern or start frame delimiter is detected, the receiver continues decoding with the same synchronization. If the stream does not match a valid pattern or a valid start frame delimiter, the receiver re-synchronizes on the next valid edge.The minimum time threshold to estimate the bit value is three quarters of a bit time. If a valid preamble (if used) followed with a valid start frame delimiter is detected, the incoming stream is decoded into NRZ data and passed to USART for processing. Figure 32-15 illustrates Manchester pattern mismatch. When incoming data stream is passed to the USART, the receiver is also able to detect Manchester code violation. A code violation is a lack of transition in the middle of a bit cell. In this case, MANE flag in US_CSR register is raised. It is cleared by writing the Control Register (US_CR) with the RSTSTA bit at 1. See Figure 32-16 for an example of Manchester error detection during data phase. Figure 32-15. Preamble Pattern Mismatch Preamble Mismatch Manchester coding error Preamble Mismatch invalid pattern Manchester encoded data Txd SFD DATA Preamble Length is set to 8 Figure 32-16. Manchester Error Flag Preamble Length is set to 4 Elementary character bit time SFD Manchester encoded data Txd Entering USART character area sampling points Preamble subpacket and Start Frame Delimiter were successfully decoded Manchester Coding Error detected 475 6384D–ATARM–04-May-09 When the start frame delimiter is a sync pattern (ONEBIT field at 0), both command and data delimiter are supported. If a valid sync is detected, the received character is written as RXCHR field in the US_RHR register and the RXSYNH is updated. RXCHR is set to 1 when the received character is a command, and it is set to 0 if the received character is a data. This mechanism alleviates and simplifies the direct memory access as the character contains its own sync field in the same register. As the decoder is setup to be used in unipolar mode, the first bit of the frame has to be a zero-toone transition. 32.6.3.6 Radio Interface: Manchester Encoded USART Application This section describes low data rate RF transmission systems and their integration with a Manchester encoded USART. These systems are based on transmitter and receiver ICs that support ASK and FSK modulation schemes. The goal is to perform full duplex radio transmission of characters using two different frequency carriers. See the configuration in Figure 32-17. Figure 32-17. Manchester Encoded Characters RF Transmission Fup frequency Carrier ASK/FSK Upstream Receiver Upstream Emitter LNA VCO RF filter Demod Serial Configuration Interface control Fdown frequency Carrier bi-dir line ASK/FSK downstream transmitter Manchester decoder USART Receiver Downstream Receiver Manchester encoder PA RF filter Mod VCO USART Emitter control The USART module is configured as a Manchester encoder/decoder. Looking at the downstream communication channel, Manchester encoded characters are serially sent to the RF emitter. This may also include a user defined preamble and a start frame delimiter. Mostly, preamble is used in the RF receiver to distinguish between a valid data from a transmitter and signals due to noise. The Manchester stream is then modulated. See Figure 32-18 for an example of ASK modulation scheme. When a logic one is sent to the ASK modulator, the power amplifier, referred to as PA, is enabled and transmits an RF signal at downstream frequency. When a logic zero is transmitted, the RF signal is turned off. If the FSK modulator is activated, two different frequencies are used to transmit data. When a logic 1 is sent, the modulator outputs an RF signal at frequency F0 and switches to F1 if the data sent is a 0. See Figure 32-19. 476 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary From the receiver side, another carrier frequency is used. The RF receiver performs a bit check operation examining demodulated data stream. If a valid pattern is detected, the receiver switches to receiving mode. The demodulated stream is sent to the Manchester decoder. Because of bit checking inside RF IC, the data transferred to the microcontroller is reduced by a user-defined number of bits. The Manchester preamble length is to be defined in accordance with the RF IC configuration. Figure 32-18. ASK Modulator Output 1 NRZ stream Manchester encoded data default polarity unipolar output ASK Modulator Output Uptstream Frequency F0 0 0 1 Txd Figure 32-19. FSK Modulator Output 1 NRZ stream Manchester encoded data default polarity unipolar output FSK Modulator Output Uptstream Frequencies [F0, F0+offset] 0 0 1 Txd 32.6.3.7 Synchronous Receiver In synchronous mode (SYNC = 1), the receiver samples the RXD signal on each rising edge of the Baud Rate Clock. If a low level is detected, it is considered as a start. All data bits, the parity bit and the stop bits are sampled and the receiver waits for the next start bit. Synchronous mode operations provide a high speed transfer capability. Configuration fields and bits are the same as in asynchronous mode. Figure 32-20 illustrates a character reception in synchronous mode. 477 6384D–ATARM–04-May-09 Figure 32-20. Synchronous Mode Character Reception Example: 8-bit, Parity Enabled 1 Stop Baud Rate Clock RXD Sampling Start D0 D1 D2 D3 D4 D5 D6 D7 Parity Bit Stop Bit 32.6.3.8 Receiver Operations When a character reception is completed, it is transferred to the Receive Holding Register (US_RHR) and the RXRDY bit in the Status Register (US_CSR) rises. If a character is completed while the RXRDY is set, the OVRE (Overrun Error) bit is set. The last character is transferred into US_RHR and overwrites the previous one. The OVRE bit is cleared by writing the Control Register (US_CR) with the RSTSTA (Reset Status) bit at 1. Figure 32-21. Receiver Status Baud Rate Clock RXD Start D0 Bit D1 D2 D3 D4 D5 D6 D7 Parity Stop Start D0 Bit Bit Bit D1 D2 D3 D4 D5 D6 D7 Parity Stop Bit Bit RSTSTA = 1 Write US_CR Read US_RHR RXRDY OVRE 478 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 32.6.3.9 Parity The USART supports five parity modes selected by programming the PAR field in the Mode Register (US_MR). The PAR field also enables the Multidrop mode, see “Multidrop Mode” on page 480. Even and odd parity bit generation and error detection are supported. If even parity is selected, the parity generator of the transmitter drives the parity bit at 0 if a number of 1s in the character data bit is even, and at 1 if the number of 1s is odd. Accordingly, the receiver parity checker counts the number of received 1s and reports a parity error if the sampled parity bit does not correspond. If odd parity is selected, the parity generator of the transmitter drives the parity bit at 1 if a number of 1s in the character data bit is even, and at 0 if the number of 1s is odd. Accordingly, the receiver parity checker counts the number of received 1s and reports a parity error if the sampled parity bit does not correspond. If the mark parity is used, the parity generator of the transmitter drives the parity bit at 1 for all characters. The receiver parity checker reports an error if the parity bit is sampled at 0. If the space parity is used, the parity generator of the transmitter drives the parity bit at 0 for all characters. The receiver parity checker reports an error if the parity bit is sampled at 1. If parity is disabled, the transmitter does not generate any parity bit and the receiver does not report any parity error. Table 32-6 shows an example of the parity bit for the character 0x41 (character ASCII “A”) depending on the configuration of the USART. Because there are two bits at 1, 1 bit is added when a parity is odd, or 0 is added when a parity is even. Table 32-6. Character A A A A A Parity Bit Examples Hexa 0x41 0x41 0x41 0x41 0x41 Binary 0100 0001 0100 0001 0100 0001 0100 0001 0100 0001 Parity Bit 1 0 1 0 None Parity Mode Odd Even Mark Space None When the receiver detects a parity error, it sets the PARE (Parity Error) bit in the Channel Status Register (US_CSR). The PARE bit can be cleared by writing the Control Register (US_CR) with the RSTSTA bit at 1. Figure 32-22 illustrates the parity bit status setting and clearing. 479 6384D–ATARM–04-May-09 Figure 32-22. Parity Error Baud Rate Clock RXD Start D0 Bit D1 D2 D3 D4 D5 D6 D7 Bad Stop Parity Bit Bit RSTSTA = 1 Write US_CR PARE RXRDY 32.6.3.10 Multidrop Mode If the PAR field in the Mode Register (US_MR) is programmed to the value 0x6 or 0x07, the USART runs in Multidrop Mode. This mode differentiates the data characters and the address characters. Data is transmitted with the parity bit at 0 and addresses are transmitted with the parity bit at 1. If the USART is configured in multidrop mode, the receiver sets the PARE parity error bit when the parity bit is high and the transmitter is able to send a character with the parity bit high when the Control Register is written with the SENDA bit at 1. To handle parity error, the PARE bit is cleared when the Control Register is written with the bit RSTSTA at 1. The transmitter sends an address byte (parity bit set) when SENDA is written to US_CR. In this case, the next byte written to US_THR is transmitted as an address. Any character written in US_THR without having written the command SENDA is transmitted normally with the parity at 0. 32.6.3.11 Transmitter Timeguard The timeguard feature enables the USART interface with slow remote devices. The timeguard function enables the transmitter to insert an idle state on the TXD line between two characters. This idle state actually acts as a long stop bit. The duration of the idle state is programmed in the TG field of the Transmitter Timeguard Register (US_TTGR). When this field is programmed at zero no timeguard is generated. Otherwise, the transmitter holds a high level on TXD after each transmitted byte during the number of bit periods programmed in TG in addition to the number of stop bits. As illustrated in Figure 32-23, the behavior of TXRDY and TXEMPTY status bits is modified by the programming of a timeguard. TXRDY rises only when the start bit of the next character is sent, and thus remains at 0 during the timeguard transmission if a character has been written in US_THR. TXEMPTY remains low until the timeguard transmission is completed as the timeguard is part of the current character being transmitted. 480 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Figure 32-23. Timeguard Operations TG = 4 Baud Rate Clock TXD Start D0 Bit D1 D2 D3 D4 D5 D6 D7 Parity Stop Bit Bit Start D0 Bit D1 D2 D3 D4 D5 D6 D7 Parity Stop Bit Bit TG = 4 Write US_THR TXRDY TXEMPTY Table 32-7 indicates the maximum length of a timeguard period that the transmitter can handle in relation to the function of the Baud Rate. Table 32-7. Maximum Timeguard Length Depending on Baud Rate Bit time µs 833 104 69.4 52.1 34.7 29.9 17.9 17.4 8.7 Timeguard ms 212.50 26.56 17.71 13.28 8.85 7.63 4.55 4.43 2.21 Baud Rate Bit/sec 1 200 9 600 14400 19200 28800 33400 56000 57600 115200 32.6.3.12 Receiver Time-out The Receiver Time-out provides support in handling variable-length frames. This feature detects an idle condition on the RXD line. When a time-out is detected, the bit TIMEOUT in the Channel Status Register (US_CSR) rises and can generate an interrupt, thus indicating to the driver an end of frame. The time-out delay period (during which the receiver waits for a new character) is programmed in the TO field of the Receiver Time-out Register (US_RTOR). If the TO field is programmed at 0, the Receiver Time-out is disabled and no time-out is detected. The TIMEOUT bit in US_CSR remains at 0. Otherwise, the receiver loads a 16-bit counter with the value programmed in TO. This counter is decremented at each bit period and reloaded each time a new character is received. If the counter reaches 0, the TIMEOUT bit in the Status Register rises. Then, the user can either: • Stop the counter clock until a new character is received. This is performed by writing the Control Register (US_CR) with the STTTO (Start Time-out) bit at 1. In this case, the idle state 481 6384D–ATARM–04-May-09 on RXD before a new character is received will not provide a time-out. This prevents having to handle an interrupt before a character is received and allows waiting for the next idle state on RXD after a frame is received. • Obtain an interrupt while no character is received. This is performed by writing US_CR with the RETTO (Reload and Start Time-out) bit at 1. If RETTO is performed, the counter starts counting down immediately from the value TO. This enables generation of a periodic interrupt so that a user time-out can be handled, for example when no key is pressed on a keyboard. If STTTO is performed, the counter clock is stopped until a first character is received. The idle state on RXD before the start of the frame does not provide a time-out. This prevents having to obtain a periodic interrupt and enables a wait of the end of frame when the idle state on RXD is detected. If RETTO is performed, the counter starts counting down immediately from the value TO. This enables generation of a periodic interrupt so that a user time-out can be handled, for example when no key is pressed on a keyboard. Figure 32-24 shows the block diagram of the Receiver Time-out feature. Figure 32-24. Receiver Time-out Block Diagram Baud Rate Clock TO 1 STTTO D Q Clock 16-bit Time-out Counter Load 16-bit Value = TIMEOUT Character Received RETTO Clear 0 Table 32-8 gives the maximum time-out period for some standard baud rates. Table 32-8. Maximum Time-out Period Bit Time µs 1 667 833 417 208 104 69 52 35 30 Time-out ms 109 225 54 613 27 306 13 653 6 827 4 551 3 413 2 276 1 962 Baud Rate bit/sec 600 1 200 2 400 4 800 9 600 14400 19200 28800 33400 482 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Table 32-8. Maximum Time-out Period (Continued) Bit Time 18 17 5 Time-out 1 170 1 138 328 Baud Rate 56000 57600 200000 32.6.3.13 Framing Error The receiver is capable of detecting framing errors. A framing error happens when the stop bit of a received character is detected at level 0. This can occur if the receiver and the transmitter are fully desynchronized. A framing error is reported on the FRAME bit of the Channel Status Register (US_CSR). The FRAME bit is asserted in the middle of the stop bit as soon as the framing error is detected. It is cleared by writing the Control Register (US_CR) with the RSTSTA bit at 1. Figure 32-25. Framing Error Status Baud Rate Clock RXD Start D0 Bit D1 D2 D3 D4 D5 D6 D7 Parity Stop Bit Bit RSTSTA = 1 Write US_CR FRAME RXRDY 32.6.3.14 Transmit Break The user can request the transmitter to generate a break condition on the TXD line. A break condition drives the TXD line low during at least one complete character. It appears the same as a 0x00 character sent with the parity and the stop bits at 0. However, the transmitter holds the TXD line at least during one character until the user requests the break condition to be removed. A break is transmitted by writing the Control Register (US_CR) with the STTBRK bit at 1. This can be performed at any time, either while the transmitter is empty (no character in either the Shift Register or in US_THR) or when a character is being transmitted. If a break is requested while a character is being shifted out, the character is first completed before the TXD line is held low. Once STTBRK command is requested further STTBRK commands are ignored until the end of the break is completed. The break condition is removed by writing US_CR with the STPBRK bit at 1. If the STPBRK is requested before the end of the minimum break duration (one character, including start, data, parity and stop bits), the transmitter ensures that the break condition completes. 483 6384D–ATARM–04-May-09 The transmitter considers the break as though it is a character, i.e. the STTBRK and STPBRK commands are taken into account only if the TXRDY bit in US_CSR is at 1 and the start of the break condition clears the TXRDY and TXEMPTY bits as if a character is processed. Writing US_CR with the both STTBRK and STPBRK bits at 1 can lead to an unpredictable result. All STPBRK commands requested without a previous STTBRK command are ignored. A byte written into the Transmit Holding Register while a break is pending, but not started, is ignored. After the break condition, the transmitter returns the TXD line to 1 for a minimum of 12 bit times. Thus, the transmitter ensures that the remote receiver detects correctly the end of break and the start of the next character. If the timeguard is programmed with a value higher than 12, the TXD line is held high for the timeguard period. After holding the TXD line for this period, the transmitter resumes normal operations. Figure 32-26 illustrates the effect of both the Start Break (STTBRK) and Stop Break (STPBRK) commands on the TXD line. Figure 32-26. Break Transmission Baud Rate Clock TXD Start D0 Bit D1 D2 D3 D4 D5 D6 D7 Parity Stop Bit Bit Break Transmission STPBRK = 1 End of Break STTBRK = 1 Write US_CR TXRDY TXEMPTY 32.6.3.15 Receive Break The receiver detects a break condition when all data, parity and stop bits are low. This corresponds to detecting a framing error with data at 0x00, but FRAME remains low. When the low stop bit is detected, the receiver asserts the RXBRK bit in US_CSR. This bit may be cleared by writing the Control Register (US_CR) with the bit RSTSTA at 1. An end of receive break is detected by a high level for at least 2/16 of a bit period in asynchronous operating mode or one sample at high level in synchronous operating mode. The end of break detection also asserts the RXBRK bit. 32.6.3.16 Hardware Handshaking The USART features a hardware handshaking out-of-band flow control. The RTS and CTS pins are used to connect with the remote device, as shown in Figure 32-27. 484 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Figure 32-27. Connection with a Remote Device for Hardware Handshaking USART TXD RXD CTS RTS Remote Device RXD TXD RTS CTS Setting the USART to operate with hardware handshaking is performed by writing the USART_MODE field in the Mode Register (US_MR) to the value 0x2. The USART behavior when hardware handshaking is enabled is the same as the behavior in standard synchronous or asynchronous mode, except that the receiver drives the RTS pin as described below and the level on the CTS pin modifies the behavior of the transmitter as described below. Using this mode requires using the PDC channel for reception. The transmitter can handle hardware handshaking in any case. Figure 32-28 shows how the receiver operates if hardware handshaking is enabled. The RTS pin is driven high if the receiver is disabled and if the status RXBUFF (Receive Buffer Full) coming from the PDC channel is high. Normally, the remote device does not start transmitting while its CTS pin (driven by RTS) is high. As soon as the Receiver is enabled, the RTS falls, indicating to the remote device that it can start transmitting. Defining a new buffer to the PDC clears the status bit RXBUFF and, as a result, asserts the pin RTS low. Figure 32-28. Receiver Behavior when Operating with Hardware Handshaking RXD RXEN = 1 Write US_CR RTS RXBUFF RXDIS = 1 Figure 32-29 shows how the transmitter operates if hardware handshaking is enabled. The CTS pin disables the transmitter. If a character is being processing, the transmitter is disabled only after the completion of the current character and transmission of the next character happens as soon as the pin CTS falls. Figure 32-29. Transmitter Behavior when Operating with Hardware Handshaking CTS TXD 485 6384D–ATARM–04-May-09 32.6.4 ISO7816 Mode The USART features an ISO7816-compatible operating mode. This mode permits interfacing with smart cards and Security Access Modules (SAM) communicating through an ISO7816 link. Both T = 0 and T = 1 protocols defined by the ISO7816 specification are supported. Setting the USART in ISO7816 mode is performed by writing the USART_MODE field in the Mode Register (US_MR) to the value 0x4 for protocol T = 0 and to the value 0x5 for protocol T = 1. 32.6.4.1 ISO7816 Mode Overview The ISO7816 is a half duplex communication on only one bidirectional line. The baud rate is determined by a division of the clock provided to the remote device (see “Baud Rate Generator” on page 464). The USART connects to a smart card as shown in Figure 32-30. The TXD line becomes bidirectional and the Baud Rate Generator feeds the ISO7816 clock on the SCK pin. As the TXD pin becomes bidirectional, its output remains driven by the output of the transmitter but only when the transmitter is active while its input is directed to the input of the receiver. The USART is considered as the master of the communication as it generates the clock. Figure 32-30. Connection of a Smart Card to the USART USART SCK TXD CLK I/O Smart Card When operating in ISO7816, either in T = 0 or T = 1 modes, the character format is fixed. The configuration is 8 data bits, even parity and 1 or 2 stop bits, regardless of the values programmed in the CHRL, MODE9, PAR and CHMODE fields. MSBF can be used to transmit LSB or MSB first. Parity Bit (PAR) can be used to transmit in normal or inverse mode. Refer to “USART Mode Register” on page 499 and “PAR: Parity Type” on page 500. The USART cannot operate concurrently in both receiver and transmitter modes as the communication is unidirectional at a time. It has to be configured according to the required mode by enabling or disabling either the receiver or the transmitter as desired. Enabling both the receiver and the transmitter at the same time in ISO7816 mode may lead to unpredictable results. The ISO7816 specification defines an inverse transmission format. Data bits of the character must be transmitted on the I/O line at their negative value. The USART does not support this format and the user has to perform an exclusive OR on the data before writing it in the Transmit Holding Register (US_THR) or after reading it in the Receive Holding Register (US_RHR). 32.6.4.2 Protocol T = 0 In T = 0 protocol, a character is made up of one start bit, eight data bits, one parity bit and one guard time, which lasts two bit times. The transmitter shifts out the bits and does not drive the I/O line during the guard time. If no parity error is detected, the I/O line remains at 1 during the guard time and the transmitter can continue with the transmission of the next character, as shown in Figure 32-31. 486 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary If a parity error is detected by the receiver, it drives the I/O line at 0 during the guard time, as shown in Figure 32-32. This error bit is also named NACK, for Non Acknowledge. In this case, the character lasts 1 bit time more, as the guard time length is the same and is added to the error bit time which lasts 1 bit time. When the USART is the receiver and it detects an error, it does not load the erroneous character in the Receive Holding Register (US_RHR). It appropriately sets the PARE bit in the Status Register (US_SR) so that the software can handle the error. Figure 32-31. T = 0 Protocol without Parity Error Baud Rate Clock RXD Start Bit D0 D1 D2 D3 D4 D5 D6 D7 Parity Guard Guard Next Bit Time 1 Time 2 Start Bit Figure 32-32. T = 0 Protocol with Parity Error Baud Rate Clock I/O Start Bit D0 D1 D2 D3 D4 D5 D6 D7 Error Parity Guard Bit Time 1 Guard Start Time 2 Bit D0 D1 Repetition 32.6.4.3 Receive Error Counter The USART receiver also records the total number of errors. This can be read in the Number of Error (US_NER) register. The NB_ERRORS field can record up to 255 errors. Reading US_NER automatically clears the NB_ERRORS field. Receive NACK Inhibit The USART can also be configured to inhibit an error. This can be achieved by setting the INACK bit in the Mode Register (US_MR). If INACK is at 1, no error signal is driven on the I/O line even if a parity bit is detected, but the INACK bit is set in the Status Register (US_SR). The INACK bit can be cleared by writing the Control Register (US_CR) with the RSTNACK bit at 1. Moreover, if INACK is set, the erroneous received character is stored in the Receive Holding Register, as if no error occurred. However, the RXRDY bit does not raise. 32.6.4.4 32.6.4.5 Transmit Character Repetition When the USART is transmitting a character and gets a NACK, it can automatically repeat the character before moving on to the next one. Repetition is enabled by writing the MAX_ITERATION field in the Mode Register (US_MR) at a value higher than 0. Each character can be transmitted up to eight times; the first transmission plus seven repetitions. If MAX_ITERATION does not equal zero, the USART repeats the character as many times as the value loaded in MAX_ITERATION. 487 6384D–ATARM–04-May-09 When the USART repetition number reaches MAX_ITERATION, the ITERATION bit is set in the Channel Status Register (US_CSR). If the repetition of the character is acknowledged by the receiver, the repetitions are stopped and the iteration counter is cleared. The ITERATION bit in US_CSR can be cleared by writing the Control Register with the RSIT bit at 1. 32.6.4.6 Disable Successive Receive NACK The receiver can limit the number of successive NACKs sent back to the remote transmitter. This is programmed by setting the bit DSNACK in the Mode Register (US_MR). The maximum number of NACK transmitted is programmed in the MAX_ITERATION field. As soon as MAX_ITERATION is reached, the character is considered as correct, an acknowledge is sent on the line and the ITERATION bit in the Channel Status Register is set. Protocol T = 1 When operating in ISO7816 protocol T = 1, the transmission is similar to an asynchronous format with only one stop bit. The parity is generated when transmitting and checked when receiving. Parity error detection sets the PARE bit in the Channel Status Register (US_CSR). IrDA Mode The USART features an IrDA mode supplying half-duplex point-to-point wireless communication. It embeds the modulator and demodulator which allows a glueless connection to the infrared transceivers, as shown in Figure 32-33. The modulator and demodulator are compliant with the IrDA specification version 1.1 and support data transfer speeds ranging from 2.4 Kb/s to 115.2 Kb/s. The USART IrDA mode is enabled by setting the USART_MODE field in the Mode Register (US_MR) to the value 0x8. The IrDA Filter Register (US_IF) allows configuring the demodulator filter. The USART transmitter and receiver operate in a normal asynchronous mode and all parameters are accessible. Note that the modulator and the demodulator are activated. Figure 32-33. Connection to IrDA Transceivers 32.6.4.7 32.6.5 USART Receiver Demodulator RXD RX TX Transmitter Modulator TXD IrDA Transceivers The receiver and the transmitter must be enabled or disabled according to the direction of the transmission to be managed. To receive IrDA signals, the following needs to be done: • Disable TX and Enable RX 488 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary • Configure the TXD pin as PIO and set it as an output at 0 (to avoid LED emission). Disable the internal pull-up (better for power consumption). • Receive data 32.6.5.1 IrDA Modulation For baud rates up to and including 115.2 Kbits/sec, the RZI modulation scheme is used. “0” is represented by a light pulse of 3/16th of a bit time. Some examples of signal pulse duration are shown in Table 32-9. Table 32-9. Baud Rate 2.4 Kb/s 9.6 Kb/s 19.2 Kb/s 38.4 Kb/s 57.6 Kb/s 115.2 Kb/s IrDA Pulse Duration Pulse Duration (3/16) 78.13 µs 19.53 µs 9.77 µs 4.88 µs 3.26 µs 1.63 µs Figure 32-34 shows an example of character transmission. Figure 32-34. IrDA Modulation Start Bit Transmitter Output 0 1 0 1 Data Bits 0 0 1 1 0 Stop Bit 1 TXD Bit Period 3 16 Bit Period 32.6.5.2 IrDA Baud Rate Table 32-10 gives some examples of CD values, baud rate error and pulse duration. Note that the requirement on the maximum acceptable error of ±1.87% must be met. Table 32-10. IrDA Baud Rate Error Peripheral Clock 3 686 400 20 000 000 32 768 000 40 000 000 3 686 400 20 000 000 32 768 000 Baud Rate 115 200 115 200 115 200 115 200 57 600 57 600 57 600 CD 2 11 18 22 4 22 36 Baud Rate Error 0.00% 1.38% 1.25% 1.38% 0.00% 1.38% 1.25% Pulse Time 1.63 1.63 1.63 1.63 3.26 3.26 3.26 489 6384D–ATARM–04-May-09 Table 32-10. IrDA Baud Rate Error (Continued) Peripheral Clock 40 000 000 3 686 400 20 000 000 32 768 000 40 000 000 3 686 400 20 000 000 32 768 000 40 000 000 3 686 400 20 000 000 32 768 000 40 000 000 3 686 400 20 000 000 32 768 000 Baud Rate 57 600 38 400 38 400 38 400 38 400 19 200 19 200 19 200 19 200 9 600 9 600 9 600 9 600 2 400 2 400 2 400 CD 43 6 33 53 65 12 65 107 130 24 130 213 260 96 521 853 Baud Rate Error 0.93% 0.00% 1.38% 0.63% 0.16% 0.00% 0.16% 0.31% 0.16% 0.00% 0.16% 0.16% 0.16% 0.00% 0.03% 0.04% Pulse Time 3.26 4.88 4.88 4.88 4.88 9.77 9.77 9.77 9.77 19.53 19.53 19.53 19.53 78.13 78.13 78.13 32.6.5.3 IrDA Demodulator The demodulator is based on the IrDA Receive filter comprised of an 8-bit down counter which is loaded with the value programmed in US_IF. When a falling edge is detected on the RXD pin, the Filter Counter starts counting down at the Master Clock (MCK) speed. If a rising edge is detected on the RXD pin, the counter stops and is reloaded with US_IF. If no rising edge is detected when the counter reaches 0, the input of the receiver is driven low during one bit time. Figure 32-35 illustrates the operations of the IrDA demodulator. Figure 32-35. IrDA Demodulator Operations MCK RXD Counter Value 6 Receiver Input 43 Pulse Rejected 5 2 6 6 5 4 3 2 1 0 Pulse Accepted As the IrDA mode uses the same logic as the ISO7816, note that the FI_DI_RATIO field in US_FIDI must be set to a value higher than 0 in order to assure IrDA communications operate correctly. 490 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 32.6.6 RS485 Mode The USART features the RS485 mode to enable line driver control. While operating in RS485 mode, the USART behaves as though in asynchronous or synchronous mode and configuration of all the parameters is possible. The difference is that the RTS pin is driven high when the transmitter is operating. The behavior of the RTS pin is controlled by the TXEMPTY bit. A typical connection of the USART to a RS485 bus is shown in Figure 32-36. Figure 32-36. Typical Connection to a RS485 Bus USART RXD TXD RTS Differential Bus The USART is set in RS485 mode by programming the USART_MODE field in the Mode Register (US_MR) to the value 0x1. The RTS pin is at a level inverse to the TXEMPTY bit. Significantly, the RTS pin remains high when a timeguard is programmed so that the line can remain driven after the last character completion. Figure 32-37 gives an example of the RTS waveform during a character transmission when the timeguard is enabled. Figure 32-37. Example of RTS Drive with Timeguard TG = 4 Baud Rate Clock TXD Start D0 Bit D1 D2 D3 D4 D5 D6 D7 Parity Stop Bit Bit Write US_THR TXRDY TXEMPTY RTS 491 6384D–ATARM–04-May-09 32.6.7 Modem Mode The USART features modem mode, which enables control of the signals: DTR (Data Terminal Ready), DSR (Data Set Ready), RTS (Request to Send), CTS (Clear to Send), DCD (Data Carrier Detect) and RI (Ring Indicator). While operating in modem mode, the USART behaves as a DTE (Data Terminal Equipment) as it drives DTR and RTS and can detect level change on DSR, DCD, CTS and RI. Setting the USART in modem mode is performed by writing the USART_MODE field in the Mode Register (US_MR) to the value 0x3. While operating in modem mode the USART behaves as though in asynchronous mode and all the parameter configurations are available. Table 32-11 gives the correspondence of the USART signals with modem connection standards. Table 32-11. Circuit References USART Pin TXD RTS DTR RXD CTS DSR DCD RI V24 2 4 20 3 5 6 8 22 CCITT 103 105 108.2 104 106 107 109 125 Direction From terminal to modem From terminal to modem From terminal to modem From modem to terminal From terminal to modem From terminal to modem From terminal to modem From terminal to modem The control of the DTR output pin is performed by writing the Control Register (US_CR) with the DTRDIS and DTREN bits respectively at 1. The disable command forces the corresponding pin to its inactive level, i.e. high. The enable command forces the corresponding pin to its active level, i.e. low. RTS output pin is automatically controlled in this mode The level changes are detected on the RI, DSR, DCD and CTS pins. If an input change is detected, the RIIC, DSRIC, DCDIC and CTSIC bits in the Channel Status Register (US_CSR) are set respectively and can trigger an interrupt. The status is automatically cleared when US_CSR is read. Furthermore, the CTS automatically disables the transmitter when it is detected at its inactive state. If a character is being transmitted when the CTS rises, the character transmission is completed before the transmitter is actually disabled. • 32.6.8 Test Modes The USART can be programmed to operate in three different test modes. The internal loopback capability allows on-board diagnostics. In the loopback mode the USART interface pins are disconnected or not and reconfigured for loopback internally or externally. 492 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 32.6.8.1 Normal Mode Normal mode connects the RXD pin on the receiver input and the transmitter output on the TXD pin. Figure 32-38. Normal Mode Configuration RXD Receiver TXD Transmitter 32.6.8.2 Automatic Echo Mode Automatic echo mode allows bit-by-bit retransmission. When a bit is received on the RXD pin, it is sent to the TXD pin, as shown in Figure 32-39. Programming the transmitter has no effect on the TXD pin. The RXD pin is still connected to the receiver input, thus the receiver remains active. Figure 32-39. Automatic Echo Mode Configuration RXD Receiver TXD Transmitter 32.6.8.3 Local Loopback Mode Local loopback mode connects the output of the transmitter directly to the input of the receiver, as shown in Figure 32-40. The TXD and RXD pins are not used. The RXD pin has no effect on the receiver and the TXD pin is continuously driven high, as in idle state. Figure 32-40. Local Loopback Mode Configuration RXD Receiver Transmitter 1 TXD 32.6.8.4 Remote Loopback Mode Remote loopback mode directly connects the RXD pin to the TXD pin, as shown in Figure 32-41. The transmitter and the receiver are disabled and have no effect. This mode allows bit-by-bit retransmission. 493 6384D–ATARM–04-May-09 Figure 32-41. Remote Loopback Mode Configuration Receiver 1 RXD TXD Transmitter 494 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 32.7 Universal Synchronous Asynchronous Receiver Transmitter (USART) User Interface Register Mapping Register Control Register Mode Register Interrupt Enable Register Interrupt Disable Register Interrupt Mask Register Channel Status Register Receiver Holding Register Transmitter Holding Register Baud Rate Generator Register Receiver Time-out Register Transmitter Timeguard Register Reserved FI DI Ratio Register Number of Errors Register Reserved IrDA Filter Register Manchester Encoder Decoder Register Reserved Reserved for PDC Registers Name US_CR US_MR US_IER US_IDR US_IMR US_CSR US_RHR US_THR US_BRGR US_RTOR US_TTGR – US_FIDI US_NER – US_IF US_MAN – – Access Write-only Read-write Write-only Write-only Read-only Read-only Read-only Write-only Read-write Read-write Read-write – Read-write Read-only – Read-write Read-write – – Reset – – – – 0x0 – 0x0 – 0x0 0x0 0x0 – 0x174 – – 0x0 0x30011004 – – Table 32-12. Offset 0x0000 0x0004 0x0008 0x000C 0x0010 0x0014 0x0018 0x001C 0x0020 0x0024 0x0028 0x2C - 0x3C 0x0040 0x0044 0x0048 0x004C 0x0050 0x5C - 0xFC 0x100 - 0x128 495 6384D–ATARM–04-May-09 32.7.1 Name: USART Control Register US_CR Write-only 30 – 22 – 14 RSTNACK 6 TXEN 29 – 21 – 13 RSTIT 5 RXDIS 28 – 20 – 12 SENDA 4 RXEN 27 – 19 RTSDIS 11 STTTO 3 RSTTX 26 – 18 RTSEN 10 STPBRK 2 RSTRX 25 – 17 DTRDIS 9 STTBRK 1 – 24 – 16 DTREN 8 RSTSTA 0 – Access Type: 31 – 23 – 15 RETTO 7 TXDIS • RSTRX: Reset Receiver 0: No effect. 1: Resets the receiver. • RSTTX: Reset Transmitter 0: No effect. 1: Resets the transmitter. • RXEN: Receiver Enable 0: No effect. 1: Enables the receiver, if RXDIS is 0. • RXDIS: Receiver Disable 0: No effect. 1: Disables the receiver. • TXEN: Transmitter Enable 0: No effect. 1: Enables the transmitter if TXDIS is 0. • TXDIS: Transmitter Disable 0: No effect. 1: Disables the transmitter. 496 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary • RSTSTA: Reset Status Bits 0: No effect. 1: Resets the status bits PARE, FRAME, OVRE, MANERR and RXBRK in US_CSR. • STTBRK: Start Break 0: No effect. 1: Starts transmission of a break after the characters present in US_THR and the Transmit Shift Register have been transmitted. No effect if a break is already being transmitted. • STPBRK: Stop Break 0: No effect. 1: Stops transmission of the break after a minimum of one character length and transmits a high level during 12-bit periods. No effect if no break is being transmitted. • STTTO: Start Time-out 0: No effect. 1: Starts waiting for a character before clocking the time-out counter. Resets the status bit TIMEOUT in US_CSR. • SENDA: Send Address 0: No effect. 1: In Multidrop Mode only, the next character written to the US_THR is sent with the address bit set. • RSTIT: Reset Iterations 0: No effect. 1: Resets ITERATION in US_CSR. No effect if the ISO7816 is not enabled. • RSTNACK: Reset Non Acknowledge 0: No effect 1: Resets NACK in US_CSR. • RETTO: Rearm Time-out 0: No effect 1: Restart Time-out • DTREN: Data Terminal Ready Enable 0: No effect. 1: Drives the pin DTR at 0. • DTRDIS: Data Terminal Ready Disable 0: No effect. 1: Drives the pin DTR to 1. • RTSEN: Request to Send Enable 0: No effect. 1: Drives the pin RTS to 0. 497 6384D–ATARM–04-May-09 • RTSDIS: Request to Send Disable 0: No effect. 1: Drives the pin RTS to 1. 498 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 32.7.2 Name: USART Mode Register US_MR Read-write 30 MODSYNC 22 VAR_SYNC 14 CHMODE 7 CHRL 6 5 USCLKS 29 MAN 21 DSNACK 13 NBSTOP 4 3 28 FILTER 20 INACK 12 27 – 19 OVER 11 26 25 MAX_ITERATION 17 MODE9 9 24 Access Type: 31 ONEBIT 23 – 15 18 CLKO 10 PAR 2 16 MSBF 8 SYNC 0 1 USART_MODE • USART_MODE USART_MODE 0 0 0 0 0 0 1 0 0 0 0 1 1 0 Others 0 0 1 1 0 1 0 0 1 0 1 0 0 0 Mode of the USART Normal RS485 Hardware Handshaking Modem IS07816 Protocol: T = 0 IS07816 Protocol: T = 1 IrDA Reserved • USCLKS: Clock Selection USCLKS 0 0 1 1 0 1 0 1 Selected Clock MCK MCK/DIV (DIV = 8) Reserved SCK • CHRL: Character Length. CHRL 0 0 1 1 0 1 0 1 Character Length 5 bits 6 bits 7 bits 8 bits 499 6384D–ATARM–04-May-09 • SYNC: Synchronous Mode Select 0: USART operates in Asynchronous Mode. 1: USART operates in Synchronous Mode. • PAR: Parity Type PAR 0 0 0 0 1 1 0 0 1 1 0 1 0 1 0 1 x x Parity Type Even parity Odd parity Parity forced to 0 (Space) Parity forced to 1 (Mark) No parity Multidrop mode • NBSTOP: Number of Stop Bits NBSTOP 0 0 1 1 0 1 0 1 Asynchronous (SYNC = 0) 1 stop bit 1.5 stop bits 2 stop bits Reserved Synchronous (SYNC = 1) 1 stop bit Reserved 2 stop bits Reserved • CHMODE: Channel Mode CHMODE 0 0 1 1 0 1 0 1 Mode Description Normal Mode Automatic Echo. Receiver input is connected to the TXD pin. Local Loopback. Transmitter output is connected to the Receiver Input.. Remote Loopback. RXD pin is internally connected to the TXD pin. • MSBF: Bit Order 0: Least Significant Bit is sent/received first. 1: Most Significant Bit is sent/received first. • MODE9: 9-bit Character Length 0: CHRL defines character length. 1: 9-bit character length. • CLKO: Clock Output Select 0: The USART does not drive the SCK pin. 1: The USART drives the SCK pin if USCLKS does not select the external clock SCK. • OVER: Oversampling Mode 0: 16x Oversampling. 500 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 1: 8x Oversampling. • INACK: Inhibit Non Acknowledge 0: The NACK is generated. 1: The NACK is not generated. • DSNACK: Disable Successive NACK 0: NACK is sent on the ISO line as soon as a parity error occurs in the received character (unless INACK is set). 1: Successive parity errors are counted up to the value specified in the MAX_ITERATION field. These parity errors generate a NACK on the ISO line. As soon as this value is reached, no additional NACK is sent on the ISO line. The flag ITERATION is asserted. • VAR_SYNC: Variable Synchronization of Command/Data Sync Start Frame Delimiter 0: User defined configuration of command or data sync field depending on SYNC value. 1: The sync field is updated when a character is written into US_THR register. • MAX_ITERATION Defines the maximum number of iterations in mode ISO7816, protocol T= 0. • FILTER: Infrared Receive Line Filter 0: The USART does not filter the receive line. • 1: The USART filters the receive line using a three-sample filter (1/16-bit clock) (2 over 3 majority).MAN: Manchester Encoder/Decoder Enable 0: Manchester Encoder/Decoder are disabled. 1: Manchester Encoder/Decoder are enabled. • MODSYNC: Manchester Synchronization Mode 0:The Manchester Start bit is a 0 to 1 transition 1: The Manchester Start bit is a 1 to 0 transition. • ONEBIT: Start Frame Delimiter Selector 0: Start Frame delimiter is COMMAND or DATA SYNC. 1: Start Frame delimiter is One Bit. 501 6384D–ATARM–04-May-09 32.7.3 Name: USART Interrupt Enable Register US_IER Write-only 30 – 22 – 14 – 6 FRAME 29 – 21 – 13 NACK 5 OVRE 28 – 20 MANE 12 RXBUFF 4 ENDTX 27 – 19 CTSIC 11 TXBUFE 3 ENDRX 26 – 18 DCDIC 10 ITER 2 RXBRK 25 – 17 DSRIC 9 TXEMPTY 1 TXRDY 24 MANE 16 RIIC 8 TIMEOUT 0 RXRDY Access Type: 31 – 23 – 15 – 7 PARE • RXRDY: RXRDY Interrupt Enable • TXRDY: TXRDY Interrupt Enable • RXBRK: Receiver Break Interrupt Enable • ENDRX: End of Receive Transfer Interrupt Enable • ENDTX: End of Transmit Interrupt Enable • OVRE: Overrun Error Interrupt Enable • FRAME: Framing Error Interrupt Enable • PARE: Parity Error Interrupt Enable • TIMEOUT: Time-out Interrupt Enable • TXEMPTY: TXEMPTY Interrupt Enable • ITER: Iteration Interrupt Enable • TXBUFE: Buffer Empty Interrupt Enable • RXBUFF: Buffer Full Interrupt Enable • NACK: Non Acknowledge Interrupt Enable • RIIC: Ring Indicator Input Change Enable • DSRIC: Data Set Ready Input Change Enable • DCDIC: Data Carrier Detect Input Change Interrupt Enable • CTSIC: Clear to Send Input Change Interrupt Enable • MANE: Manchester Error Interrupt Enable 502 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 32.7.4 Name: USART Interrupt Disable Register US_IDR Write-only 30 – 22 – 14 – 6 FRAME 29 – 21 – 13 NACK 5 OVRE 28 – 20 MANE 12 RXBUFF 4 ENDTX 27 – 19 CTSIC 11 TXBUFE 3 ENDRX 26 – 18 DCDIC 10 ITER 2 RXBRK 25 – 17 DSRIC 9 TXEMPTY 1 TXRDY 24 MANE 16 RIIC 8 TIMEOUT 0 RXRDY Access Type: 31 – 23 – 15 – 7 PARE • RXRDY: RXRDY Interrupt Disable • TXRDY: TXRDY Interrupt Disable • RXBRK: Receiver Break Interrupt Disable • ENDRX: End of Receive Transfer Interrupt Disable • ENDTX: End of Transmit Interrupt Disable • OVRE: Overrun Error Interrupt Disable • FRAME: Framing Error Interrupt Disable • PARE: Parity Error Interrupt Disable • TIMEOUT: Time-out Interrupt Disable • TXEMPTY: TXEMPTY Interrupt Disable • ITER: Iteration Interrupt Enable • TXBUFE: Buffer Empty Interrupt Disable • RXBUFF: Buffer Full Interrupt Disable • NACK: Non Acknowledge Interrupt Disable • RIIC: Ring Indicator Input Change Disable • DSRIC: Data Set Ready Input Change Disable • DCDIC: Data Carrier Detect Input Change Interrupt Disable • CTSIC: Clear to Send Input Change Interrupt Disable • MANE: Manchester Error Interrupt Disable 503 6384D–ATARM–04-May-09 32.7.5 Name: USART Interrupt Mask Register US_IMR Read-only 30 – 22 – 14 – 6 FRAME 29 – 21 – 13 NACK 5 OVRE 28 – 20 MANE 12 RXBUFF 4 ENDTX 27 – 19 CTSIC 11 TXBUFE 3 ENDRX 26 – 18 DCDIC 10 ITER 2 RXBRK 25 – 17 DSRIC 9 TXEMPTY 1 TXRDY 24 MANE 16 RIIC 8 TIMEOUT 0 RXRDY Access Type: 31 – 23 – 15 – 7 PARE • RXRDY: RXRDY Interrupt Mask • TXRDY: TXRDY Interrupt Mask • RXBRK: Receiver Break Interrupt Mask • ENDRX: End of Receive Transfer Interrupt Mask • ENDTX: End of Transmit Interrupt Mask • OVRE: Overrun Error Interrupt Mask • FRAME: Framing Error Interrupt Mask • PARE: Parity Error Interrupt Mask • TIMEOUT: Time-out Interrupt Mask • TXEMPTY: TXEMPTY Interrupt Mask • ITER: Iteration Interrupt Enable • TXBUFE: Buffer Empty Interrupt Mask • RXBUFF: Buffer Full Interrupt Mask • NACK: Non Acknowledge Interrupt Mask • RIIC: Ring Indicator Input Change Mask • DSRIC: Data Set Ready Input Change Mask • DCDIC: Data Carrier Detect Input Change Interrupt Mask • CTSIC: Clear to Send Input Change Interrupt Mask • MANE: Manchester Error Interrupt Mask 504 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 32.7.6 Name: USART Channel Status Register US_CSR Read-only 30 – 22 DCD 14 – 6 FRAME 29 – 21 DSR 13 NACK 5 OVRE 28 – 20 RI 12 RXBUFF 4 ENDTX 27 – 19 CTSIC 11 TXBUFE 3 ENDRX 26 – 18 DCDIC 10 ITER 2 RXBRK 25 – 17 DSRIC 9 TXEMPTY 1 TXRDY 24 MANERR 16 RIIC 8 TIMEOUT 0 RXRDY Access Type: 31 – 23 CTS 15 – 7 PARE • RXRDY: Receiver Ready 0: No complete character has been received since the last read of US_RHR or the receiver is disabled. If characters were being received when the receiver was disabled, RXRDY changes to 1 when the receiver is enabled. 1: At least one complete character has been received and US_RHR has not yet been read. • TXRDY: Transmitter Ready 0: A character is in the US_THR waiting to be transferred to the Transmit Shift Register, or an STTBRK command has been requested, or the transmitter is disabled. As soon as the transmitter is enabled, TXRDY becomes 1. 1: There is no character in the US_THR. • RXBRK: Break Received/End of Break 0: No Break received or End of Break detected since the last RSTSTA. 1: Break Received or End of Break detected since the last RSTSTA. • ENDRX: End of Receiver Transfer 0: The End of Transfer signal from the Receive PDC channel is inactive. 1: The End of Transfer signal from the Receive PDC channel is active. • ENDTX: End of Transmitter Transfer 0: The End of Transfer signal from the Transmit PDC channel is inactive. 1: The End of Transfer signal from the Transmit PDC channel is active. • OVRE: Overrun Error 0: No overrun error has occurred since the last RSTSTA. 1: At least one overrun error has occurred since the last RSTSTA. 505 6384D–ATARM–04-May-09 • FRAME: Framing Error 0: No stop bit has been detected low since the last RSTSTA. 1: At least one stop bit has been detected low since the last RSTSTA. • PARE: Parity Error 0: No parity error has been detected since the last RSTSTA. 1: At least one parity error has been detected since the last RSTSTA. • TIMEOUT: Receiver Time-out 0: There has not been a time-out since the last Start Time-out command (STTTO in US_CR) or the Time-out Register is 0. 1: There has been a time-out since the last Start Time-out command (STTTO in US_CR). • TXEMPTY: Transmitter Empty 0: There are characters in either US_THR or the Transmit Shift Register, or the transmitter is disabled. 1: There are no characters in US_THR, nor in the Transmit Shift Register. • ITER: Max number of Repetitions Reached 0: Maximum number of repetitions has not been reached since the last RSTSTA. 1: Maximum number of repetitions has been reached since the last RSTSTA. • TXBUFE: Transmission Buffer Empty 0: The signal Buffer Empty from the Transmit PDC channel is inactive. 1: The signal Buffer Empty from the Transmit PDC channel is active. • RXBUFF: Reception Buffer Full 0: The signal Buffer Full from the Receive PDC channel is inactive. 1: The signal Buffer Full from the Receive PDC channel is active. • NACK: Non Acknowledge 0: No Non Acknowledge has not been detected since the last RSTNACK. 1: At least one Non Acknowledge has been detected since the last RSTNACK. • RIIC: Ring Indicator Input Change Flag 0: No input change has been detected on the RI pin since the last read of US_CSR. 1: At least one input change has been detected on the RI pin since the last read of US_CSR. • DSRIC: Data Set Ready Input Change Flag 0: No input change has been detected on the DSR pin since the last read of US_CSR. 1: At least one input change has been detected on the DSR pin since the last read of US_CSR. • DCDIC: Data Carrier Detect Input Change Flag 0: No input change has been detected on the DCD pin since the last read of US_CSR. 1: At least one input change has been detected on the DCD pin since the last read of US_CSR. • CTSIC: Clear to Send Input Change Flag 0: No input change has been detected on the CTS pin since the last read of US_CSR. 506 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 1: At least one input change has been detected on the CTS pin since the last read of US_CSR. • RI: Image of RI Input 0: RI is at 0. 1: RI is at 1. • DSR: Image of DSR Input 0: DSR is at 0 1: DSR is at 1. • DCD: Image of DCD Input 0: DCD is at 0. 1: DCD is at 1. • CTS: Image of CTS Input 0: CTS is at 0. 1: CTS is at 1. • MANERR: Manchester Error 0: No Manchester error has been detected since the last RSTSTA. 1: At least one Manchester error has been detected since the last RSTSTA. 507 6384D–ATARM–04-May-09 32.7.7 Name: USART Receive Holding Register US_RHR Read-only 30 – 22 – 14 – 6 29 – 21 – 13 – 5 28 – 20 – 12 – 4 RXCHR 27 – 19 – 11 – 3 26 – 18 – 10 – 2 25 – 17 – 9 – 1 24 – 16 – 8 RXCHR 0 Access Type: 31 – 23 – 15 RXSYNH 7 • RXCHR: Received Character Last character received if RXRDY is set. • RXSYNH: Received Sync 0: Last Character received is a Data. 1: Last Character received is a Command. 508 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 32.7.8 Name: USART Transmit Holding Register US_THR Write-only 30 – 22 – 14 – 6 29 – 21 – 13 – 5 28 – 20 – 12 – 4 TXCHR 27 – 19 – 11 – 3 26 – 18 – 10 – 2 25 – 17 – 9 – 1 24 – 16 – 8 TXCHR 0 Access Type: 31 – 23 – 15 TXSYNH 7 • TXCHR: Character to be Transmitted Next character to be transmitted after the current character if TXRDY is not set. • TXSYNH: Sync Field to be transmitted 0: The next character sent is encoded as a data. Start Frame Delimiter is DATA SYNC. 1: The next character sent is encoded as a command. Start Frame Delimiter is COMMAND SYNC. 509 6384D–ATARM–04-May-09 32.7.9 Name: USART Baud Rate Generator Register US_BRGR Read-write 30 – 22 – 14 29 – 21 – 13 28 – 20 – 12 CD 7 6 5 4 CD 3 2 1 0 27 – 19 – 11 26 – 18 25 – 17 FP– 9 24 – 16 Access Type: 31 – 23 – 15 10 8 • CD: Clock Divider USART_MODE ≠ ISO7816 SYNC = 0 CD 0 1 to 65535 Baud Rate = Selected Clock/16/CD OVER = 0 OVER = 1 Baud Rate Clock Disabled Baud Rate = Selected Clock/8/CD Baud Rate = Selected Clock /CD Baud Rate = Selected Clock/CD/FI_DI_RATIO SYNC = 1 USART_MODE = ISO7816 • FP: Fractional Part 0: Fractional divider is disabled. 1 - 7: Baudrate resolution, defined by FP x 1/8. 510 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 32.7.10 Name: USART Receiver Time-out Register US_RTOR Read-write 30 29 28 27 26 25 24 Access Type: 31 – 23 – 15 – 22 – 14 – 21 – 13 – 20 – 12 TO – 19 – 11 – 18 – 10 – 17 – 9 – 16 – 8 7 6 5 4 TO 3 2 1 0 • TO: Time-out Value 0: The Receiver Time-out is disabled. 1 - 65535: The Receiver Time-out is enabled and the Time-out delay is TO x Bit Period. 511 6384D–ATARM–04-May-09 32.7.11 Name: USART Transmitter Timeguard Register US_TTGR Read-write 30 – 22 – 14 – 6 29 – 21 – 13 – 5 28 – 20 – 12 – 4 TG 27 – 19 – 11 – 3 26 – 18 – 10 – 2 25 – 17 – 9 – 1 24 – 16 – 8 – 0 Access Type: 31 – 23 – 15 – 7 • TG: Timeguard Value 0: The Transmitter Timeguard is disabled. 1 - 255: The Transmitter timeguard is enabled and the timeguard delay is TG x Bit Period. 512 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 32.7.12 Name: USART FI DI RATIO Register US_FIDI Read-write 0x174 30 – 22 – 14 – 6 29 – 21 – 13 – 5 28 – 20 – 12 – 4 FI_DI_RATIO 27 – 19 – 11 – 3 26 – 18 – 10 25 – 17 – 9 FI_DI_RATIO 1 24 – 16 – 8 Access Type: Reset Value: 31 – 23 – 15 – 7 2 0 • FI_DI_RATIO: FI Over DI Ratio Value 0: If ISO7816 mode is selected, the Baud Rate Generator generates no signal. 1 - 2047: If ISO7816 mode is selected, the Baud Rate is the clock provided on SCK divided by FI_DI_RATIO. 32.7.13 Name: USART Number of Errors Register US_NER Read-only 30 – 22 – 14 – 6 29 – 21 – 13 – 5 28 – 20 – 12 – 4 NB_ERRORS 27 – 19 – 11 – 3 26 – 18 – 10 – 2 25 – 17 – 9 – 1 24 – 16 – 8 – 0 Access Type: 31 – 23 – 15 – 7 • NB_ERRORS: Number of Errors Total number of errors that occurred during an ISO7816 transfer. This register automatically clears when read. 513 6384D–ATARM–04-May-09 32.7.14 Name: USART IrDA FILTER Register US_IF Read-write 30 – 22 – 14 – 6 29 – 21 – 13 – 5 28 – 20 – 12 – 4 IRDA_FILTER 27 – 19 – 11 – 3 26 – 18 – 10 – 2 25 – 17 – 9 – 1 24 – 16 – 8 – 0 Access Type: 31 – 23 – 15 – 7 • IRDA_FILTER: IrDA Filter Sets the filter of the IrDA demodulator. 514 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 32.7.15 Name: USART Manchester Configuration Register US_MAN Read-write 30 DRIFT 22 – 14 – 6 – 29 1 21 – 13 – 5 – 28 RX_MPOL 20 – 12 TX_MPOL 4 – 27 – 19 26 – 18 RX_PL 11 – 3 10 – 2 TX_PL 9 TX_PP 1 0 8 25 RX_PP 17 16 24 Access Type: 31 – 23 – 15 – 7 – • TX_PL: Transmitter Preamble Length 0: The Transmitter Preamble pattern generation is disabled 1 - 15: The Preamble Length is TX_PL x Bit Period • TX_PP: Transmitter Preamble Pattern TX_PP 0 0 1 1 0 1 0 1 Preamble Pattern default polarity assumed (TX_MPOL field not set) ALL_ONE ALL_ZERO ZERO_ONE ONE_ZERO • TX_MPOL: Transmitter Manchester Polarity 0: Logic Zero is coded as a zero-to-one transition, Logic One is coded as a one-to-zero transition. 1: Logic Zero is coded as a one-to-zero transition, Logic One is coded as a zero-to-one transition. • RX_PL: Receiver Preamble Length 0: The receiver preamble pattern detection is disabled 1 - 15: The detected preamble length is RX_PL x Bit Period • RX_PP: Receiver Preamble Pattern detected RX_PP 0 0 1 1 0 1 0 1 Preamble Pattern default polarity assumed (RX_MPOL field not set) ALL_ONE ALL_ZERO ZERO_ONE ONE_ZERO 515 6384D–ATARM–04-May-09 • RX_MPOL: Receiver Manchester Polarity 0: Logic Zero is coded as a zero-to-one transition, Logic One is coded as a one-to-zero transition. 1: Logic Zero is coded as a one-to-zero transition, Logic One is coded as a zero-to-one transition. • DRIFT: Drift compensation 0: The USART can not recover from an important clock drift 1: The USART can recover from clock drift. The 16X clock mode must be enabled. 516 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 33. Synchronous Serial Controller (SSC) 33.1 Overview The Atmel Synchronous Serial Controller (SSC) provides a synchronous communication link with external devices. It supports many serial synchronous communication protocols generally used in audio and telecom applications such as I2S, Short Frame Sync, Long Frame Sync, etc. The SSC contains an independent receiver and transmitter and a common clock divider. The receiver and the transmitter each interface with three signals: the TD/RD signal for data, the TK/RK signal for the clock and the TF/RF signal for the Frame Sync. The transfers can be programmed to start automatically or on different events detected on the Frame Sync signal. The SSC’s high-level of programmability and its two dedicated PDC channels of up to 32 bits permit a continuous high bit rate data transfer without processor intervention. Featuring connection to two PDC channels, the SSC permits interfacing with low processor overhead to the following: • CODEC’s in master or slave mode • DAC through dedicated serial interface, particularly I2S • Magnetic card reader 517 6384D–ATARM–04-May-09 33.2 Block Diagram Figure 33-1. Block Diagram System Bus APB Bridge PDC Peripheral Bus TF TK TD SSC Interface PIO RF RK Interrupt Control RD PMC MCK SSC Interrupt 33.3 Application Block Diagram Figure 33-2. Application Block Diagram OS or RTOS Driver Power Management SSC Time Slot Management Frame Management Interrupt Management Test Management Serial AUDIO Codec Line Interface 518 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 33.4 Pin Name List I/O Lines Description Pin Description Receiver Frame Synchro Receiver Clock Receiver Data Transmitter Frame Synchro Transmitter Clock Transmitter Data Type Input/Output Input/Output Input Input/Output Input/Output Output Table 33-1. Pin Name RF RK RD TF TK TD 33.5 33.5.1 Product Dependencies I/O Lines The pins used for interfacing the compliant external devices may be multiplexed with PIO lines. Before using the SSC receiver, the PIO controller must be configured to dedicate the SSC receiver I/O lines to the SSC peripheral mode. Before using the SSC transmitter, the PIO controller must be configured to dedicate the SSC transmitter I/O lines to the SSC peripheral mode. 33.5.2 Power Management The SSC is not continuously clocked. The SSC interface may be clocked through the Power Management Controller (PMC), therefore the programmer must first configure the PMC to enable the SSC clock. Interrupt The SSC interface has an interrupt line connected to the Advanced Interrupt Controller (AIC). Handling interrupts requires programming the AIC before configuring the SSC. All SSC interrupts can be enabled/disabled configuring the SSC Interrupt mask register. Each pending and unmasked SSC interrupt will assert the SSC interrupt line. The SSC interrupt service routine can get the interrupt origin by reading the SSC interrupt status register. 33.5.3 33.6 Functional Description This chapter contains the functional description of the following: SSC Functional Block, Clock Management, Data format, Start, Transmitter, Receiver and Frame Sync. The receiver and transmitter operate separately. However, they can work synchronously by programming the receiver to use the transmit clock and/or to start a data transfer when transmission starts. Alternatively, this can be done by programming the transmitter to use the receive clock and/or to start a data transfer when reception starts. The transmitter and the receiver can be programmed to operate with the clock signals provided on either the TK or RK pins. This allows the SSC to support many slave-mode data transfers. The maximum clock speed allowed on the TK and RK pins is the master clock divided by 2. 519 6384D–ATARM–04-May-09 Figure 33-3. SSC Functional Block Diagram Transmitter Clock Output Controller TK MCK Clock Divider TK Input RX clock TF RF Start Selector TX PDC Transmit Clock Controller TX clock Frame Sync Controller TF Transmit Shift Register Transmit Holding Register Transmit Sync Holding Register TD APB User Interface Load Shift Receiver Clock Output Controller RK RK Input TX Clock RF TF Start Selector Receive Clock RX Clock Controller Frame Sync Controller RF Receive Shift Register Receive Holding Register Receive Sync Holding Register RD RX PDC PDC Interrupt Control Load Shift AIC 33.6.1 Clock Management The transmitter clock can be generated by: • an external clock received on the TK I/O pad • the receiver clock • the internal clock divider The receiver clock can be generated by: • an external clock received on the RK I/O pad • the transmitter clock • the internal clock divider Furthermore, the transmitter block can generate an external clock on the TK I/O pad, and the receiver block can generate an external clock on the RK I/O pad. This allows the SSC to support many Master and Slave Mode data transfers. 520 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 33.6.1.1 Clock Divider Figure 33-4. Divided Clock Block Diagram Clock Divider SSC_CMR MCK /2 12-bit Counter Divided Clock The Master Clock divider is determined by the 12-bit field DIV counter and comparator (so its maximal value is 4095) in the Clock Mode Register SSC_CMR, allowing a Master Clock division by up to 8190. The Divided Clock is provided to both the Receiver and Transmitter. When this field is programmed to 0, the Clock Divider is not used and remains inactive. When DIV is set to a value equal to or greater than 1, the Divided Clock has a frequency of Master Clock divided by 2 times DIV. Each level of the Divided Clock has a duration of the Master Clock multiplied by DIV. This ensures a 50% duty cycle for the Divided Clock regardless of whether the DIV value is even or odd. Figure 33-5. Divided Clock Generation Master Clock Divided Clock DIV = 1 Divided Clock Frequency = MCK/2 Master Clock Divided Clock DIV = 3 Divided Clock Frequency = MCK/6 Table 33-2. Maximum MCK / 2 Minimum MCK / 8190 33.6.1.2 Transmitter Clock Management The transmitter clock is generated from the receiver clock or the divider clock or an external clock scanned on the TK I/O pad. The transmitter clock is selected by the CKS field in SSC_TCMR (Transmit Clock Mode Register). Transmit Clock can be inverted independently by the CKI bits in SSC_TCMR. 521 6384D–ATARM–04-May-09 The transmitter can also drive the TK I/O pad continuously or be limited to the actual data transfer. The clock output is configured by the SSC_TCMR register. The Transmit Clock Inversion (CKI) bits have no effect on the clock outputs. Programming the TCMR register to select TK pin (CKS field) and at the same time Continuous Transmit Clock (CKO field) might lead to unpredictable results. Figure 33-6. Transmitter Clock Management TK (pin) MUX Receiver Clock Tri_state Controller Clock Output Divider Clock CKO Data Transfer CKS INV MUX Tri-state Controller Transmitter Clock CKI CKG 33.6.1.3 Receiver Clock Management The receiver clock is generated from the transmitter clock or the divider clock or an external clock scanned on the RK I/O pad. The Receive Clock is selected by the CKS field in SSC_RCMR (Receive Clock Mode Register). Receive Clocks can be inverted independently by the CKI bits in SSC_RCMR. The receiver can also drive the RK I/O pad continuously or be limited to the actual data transfer. The clock output is configured by the SSC_RCMR register. The Receive Clock Inversion (CKI) bits have no effect on the clock outputs. Programming the RCMR register to select RK pin (CKS field) and at the same time Continuous Receive Clock (CKO field) can lead to unpredictable results. 522 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Figure 33-7. Receiver Clock Management RK (pin) Tri-state Controller MUX Transmitter Clock Clock Output Divider Clock CKO Data Transfer CKS INV MUX Tri-state Controller Receiver Clock CKI CKG 33.6.1.4 Serial Clock Ratio Considerations The Transmitter and the Receiver can be programmed to operate with the clock signals provided on either the TK or RK pins. This allows the SSC to support many slave-mode data transfers. In this case, the maximum clock speed allowed on the RK pin is: – Master Clock divided by 2 if Receiver Frame Synchro is input – Master Clock divided by 3 if Receiver Frame Synchro is output In addition, the maximum clock speed allowed on the TK pin is: – Master Clock divided by 6 if Transmit Frame Synchro is input – Master Clock divided by 2 if Transmit Frame Synchro is output 33.6.2 Transmitter Operations A transmitted frame is triggered by a start event and can be followed by synchronization data before data transmission. The start event is configured by setting the Transmit Clock Mode Register (SSC_TCMR). See “Start” on page 525. The frame synchronization is configured setting the Transmit Frame Mode Register (SSC_TFMR). See “Frame Sync” on page 527. To transmit data, the transmitter uses a shift register clocked by the transmitter clock signal and the start mode selected in the SSC_TCMR. Data is written by the application to the SSC_THR register then transferred to the shift register according to the data format selected. When both the SSC_THR and the transmit shift register are empty, the status flag TXEMPTY is set in SSC_SR. When the Transmit Holding register is transferred in the Transmit shift register, the status flag TXRDY is set in SSC_SR and additional data can be loaded in the holding register. 523 6384D–ATARM–04-May-09 Figure 33-8. Transmitter Block Diagram SSC_CR.TXEN SSC_SR.TXEN SSC_CR.TXDIS SSC_TFMR.DATDEF 1 RF Transmitter Clock TF SSC_TFMR.MSBF 0 SSC_TCMR.STTDLY SSC_TFMR.FSDEN SSC_TFMR.DATNB TD Start Selector Transmit Shift Register SSC_TFMR.FSDEN SSC_TCMR.STTDLY SSC_TFMR.DATLEN SSC_THR 0 1 SSC_TSHR SSC_TFMR.FSLEN 33.6.3 Receiver Operations A received frame is triggered by a start event and can be followed by synchronization data before data transmission. The start event is configured setting the Receive Clock Mode Register (SSC_RCMR). See “Start” on page 525. The frame synchronization is configured setting the Receive Frame Mode Register (SSC_RFMR). See “Frame Sync” on page 527. The receiver uses a shift register clocked by the receiver clock signal and the start mode selected in the SSC_RCMR. The data is transferred from the shift register depending on the data format selected. When the receiver shift register is full, the SSC transfers this data in the holding register, the status flag RXRDY is set in SSC_SR and the data can be read in the receiver holding register. If another transfer occurs before read of the RHR register, the status flag OVERUN is set in SSC_SR and the receiver shift register is transferred in the RHR register. 524 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Figure 33-9. Receiver Block Diagram SSC_CR.RXEN SSC_SR.RXEN SSC_CR.RXDIS RF Receiver Clock TF SSC_RFMR.MSBF SSC_RFMR.DATNB Start Selector Receive Shift Register RD SSC_RSHR SSC_RCMR.STTDLY SSC_RFMR.FSLEN SSC_RHR SSC_RFMR.DATLEN 33.6.4 Start The transmitter and receiver can both be programmed to start their operations when an event occurs, respectively in the Transmit Start Selection (START) field of SSC_TCMR and in the Receive Start Selection (START) field of SSC_RCMR. Under the following conditions the start event is independently programmable: • Continuous. In this case, the transmission starts as soon as a word is written in SSC_THR and the reception starts as soon as the Receiver is enabled. • Synchronously with the transmitter/receiver • On detection of a falling/rising edge on TF/RF • On detection of a low level/high level on TF/RF • On detection of a level change or an edge on TF/RF A start can be programmed in the same manner on either side of the Transmit/Receive Clock Register (RCMR/TCMR). Thus, the start could be on TF (Transmit) or RF (Receive). Moreover, the Receiver can start when data is detected in the bit stream with the Compare Functions. Detection on TF/RF input/output is done by the field FSOS of the Transmit/Receive Frame Mode Register (TFMR/RFMR). 525 6384D–ATARM–04-May-09 Figure 33-10. Transmit Start Mode TK TF (Input) Start = Low Level on TF TD (Output) TD (Output) X BO B1 STTDLY Start = Falling Edge on TF X BO B1 STTDLY X BO B1 STTDLY Start = High Level on TF TD (Output) TD (Output) TD (Output) TD (Output) X Start = Rising Edge on TF BO B1 STTDLY Start = Level Change on TF X BO B1 BO B1 STTDLY Start = Any Edge on TF X BO B1 BO B1 STTDLY Figure 33-11. Receive Pulse/Edge Start Modes RK RF (Input) Start = Low Level on RF RD (Input) RD (Input) X BO B1 STTDLY Start = Falling Edge on RF X BO B1 STTDLY X BO B1 STTDLY Start = High Level on RF RD (Input) RD (Input) RD (Input) RD (Input) X Start = Rising Edge on RF BO B1 STTDLY Start = Level Change on RF X BO B1 BO B1 STTDLY Start = Any Edge on RF X BO B1 BO B1 STTDLY 526 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 33.6.5 Frame Sync The Transmitter and Receiver Frame Sync pins, TF and RF, can be programmed to generate different kinds of frame synchronization signals. The Frame Sync Output Selection (FSOS) field in the Receive Frame Mode Register (SSC_RFMR) and in the Transmit Frame Mode Register (SSC_TFMR) are used to select the required waveform. • Programmable low or high levels during data transfer are supported. • Programmable high levels before the start of data transfers or toggling are also supported. If a pulse waveform is selected, the Frame Sync Length (FSLEN) field in SSC_RFMR and SSC_TFMR programs the length of the pulse, from 1 bit time up to 256 bit time. The periodicity of the Receive and Transmit Frame Sync pulse output can be programmed through the Period Divider Selection (PERIOD) field in SSC_RCMR and SSC_TCMR. 33.6.5.1 Frame Sync Data Frame Sync Data transmits or receives a specific tag during the Frame Sync signal. During the Frame Sync signal, the Receiver can sample the RD line and store the data in the Receive Sync Holding Register and the transmitter can transfer Transmit Sync Holding Register in the Shifter Register. The data length to be sampled/shifted out during the Frame Sync signal is programmed by the FSLEN field in SSC_RFMR/SSC_TFMR and has a maximum value of 16. Concerning the Receive Frame Sync Data operation, if the Frame Sync Length is equal to or lower than the delay between the start event and the actual data reception, the data sampling operation is performed in the Receive Sync Holding Register through the Receive Shift Register. The Transmit Frame Sync Operation is performed by the transmitter only if the bit Frame Sync Data Enable (FSDEN) in SSC_TFMR is set. If the Frame Sync length is equal to or lower than the delay between the start event and the actual data transmission, the normal transmission has priority and the data contained in the Transmit Sync Holding Register is transferred in the Transmit Register, then shifted out. 33.6.5.2 Frame Sync Edge Detection The Frame Sync Edge detection is programmed by the FSEDGE field in SSC_RFMR/SSC_TFMR. This sets the corresponding flags RXSYN/TXSYN in the SSC Status Register (SSC_SR) on frame synchro edge detection (signals RF/TF). Receive Compare Modes Figure 33-12. Receive Compare Modes RK 33.6.6 RD (Input) CMP0 CMP1 CMP2 CMP3 Start Ignored B0 B1 B2 FSLEN Up to 16 Bits (4 in This Example) STDLY DATLEN 527 6384D–ATARM–04-May-09 33.6.6.1 Compare Functions Length of the comparison patterns (Compare 0, Compare 1) and thus the number of bits they are compared to is defined by FSLEN, but with a maximum value of 16 bits. Comparison is always done by comparing the last bits received with the comparison pattern. Compare 0 can be one start event of the Receiver. In this case, the receiver compares at each new sample the last bits received at the Compare 0 pattern contained in the Compare 0 Register (SSC_RC0R). When this start event is selected, the user can program the Receiver to start a new data transfer either by writing a new Compare 0, or by receiving continuously until Compare 1 occurs. This selection is done with the bit (STOP) in SSC_RCMR. Data Format The data framing format of both the transmitter and the receiver are programmable through the Transmitter Frame Mode Register (SSC_TFMR) and the Receiver Frame Mode Register (SSC_RFMR). In either case, the user can independently select: • the event that starts the data transfer (START) • the delay in number of bit periods between the start event and the first data bit (STTDLY) • the length of the data (DATLEN) • the number of data to be transferred for each start event (DATNB). • the length of synchronization transferred for each start event (FSLEN) • the bit sense: most or lowest significant bit first (MSBF) Additionally, the transmitter can be used to transfer synchronization and select the level driven on the TD pin while not in data transfer operation. This is done respectively by the Frame Sync Data Enable (FSDEN) and by the Data Default Value (DATDEF) bits in SSC_TFMR. 33.6.7 528 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Table 33-3. Transmitter SSC_TFMR SSC_TFMR SSC_TFMR SSC_TFMR SSC_TFMR SSC_TFMR SSC_TCMR SSC_TCMR SSC_RCMR SSC_RCMR Data Frame Registers Receiver SSC_RFMR SSC_RFMR SSC_RFMR SSC_RFMR Field DATLEN DATNB MSBF FSLEN DATDEF FSDEN PERIOD STTDLY Up to 512 Up to 255 Up to 16 0 or 1 Length Up to 32 Up to 16 Comment Size of word Number of words transmitted in frame Most significant bit first Size of Synchro data register Data default value ended Enable send SSC_TSHR Frame size Size of transmit start delay Figure 33-13. Transmit and Receive Frame Format in Edge/Pulse Start Modes Start PERIOD TF/RF (1) Start FSLEN TD (If FSDEN = 1) Sync Data Default Data From SSC_THR Data From SSC_THR Data To SSC_RHR DATLEN Data From SSC_THR Data From SSC_THR Data To SSC_RHR DATLEN Default FromDATDEF Default From DATDEF Ignored Sync Data Sync Data From SSC_TSHR FromDATDEF Default From DATDEF Sync Data To SSC_RSHR STTDLY Ignored TD (If FSDEN = 0) RD DATNB Note: 1. Example of input on falling edge of TF/RF. Figure 33-14. Transmit Frame Format in Continuous Mode Start TD Data From SSC_THR DATLEN Data From SSC_THR DATLEN Default Start: 1. TXEMPTY set to 1 2. Write into the SSC_THR 529 6384D–ATARM–04-May-09 Note: 1. STTDLY is set to 0. In this example, SSC_THR is loaded twice. FSDEN value has no effect on the transmission. SyncData cannot be output in continuous mode. Figure 33-15. Receive Frame Format in Continuous Mode Start = Enable Receiver RD Data To SSC_RHR DATLEN Data To SSC_RHR DATLEN Note: 1. STTDLY is set to 0. 33.6.8 Loop Mode The receiver can be programmed to receive transmissions from the transmitter. This is done by setting the Loop Mode (LOOP) bit in SSC_RFMR. In this case, RD is connected to TD, RF is connected to TF and RK is connected to TK. 33.6.9 Interrupt Most bits in SSC_SR have a corresponding bit in interrupt management registers. The SSC can be programmed to generate an interrupt when it detects an event. The interrupt is controlled by writing SSC_IER (Interrupt Enable Register) and SSC_IDR (Interrupt Disable Register) These registers enable and disable, respectively, the corresponding interrupt by setting and clearing the corresponding bit in SSC_IMR (Interrupt Mask Register), which controls the generation of interrupts by asserting the SSC interrupt line connected to the AIC. Figure 33-16. Interrupt Block Diagram SSC_IMR SSC_IER PDC TXBUFE ENDTX Transmitter TXRDY TXEMPTY TXSYNC RXBUFF ENDRX Receiver RXRDY OVRUN RXSYNC Interrupt Control Set SSC_IDR Clear SSC Interrupt 530 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 33.7 SSC Application Examples The SSC can support several serial communication modes used in audio or high speed serial links. Some standard applications are shown in the following figures. All serial link applications supported by the SSC are not listed here. Figure 33-17. Audio Application Block Diagram Clock SCK TK Word Select WS TF Data SD SSC TD RD RF RK I2S RECEIVER Clock SCK Word Select WS Data SD MSB Left Channel LSB MSB Right Channel Figure 33-18. Codec Application Block Diagram Serial Data Clock (SCLK) TK Frame sync (FSYNC) TF Serial Data Out SSC TD Serial Data In RD RF RK CODEC Serial Data Clock (SCLK) Frame sync (FSYNC) First Time Slot Dstart Serial Data Out Dend Serial Data In 531 6384D–ATARM–04-May-09 Figure 33-19. Time Slot Application Block Diagram SCLK TK FSYNC TF Data Out TD SSC RD RF RK Data in CODEC First Time Slot CODEC Second Time Slot Serial Data Clock (SCLK) Frame sync (FSYNC) Serial Data Out First Time Slot Dstart Second Time Slot Dend Serial Data in 532 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 33.8 Syncrhronous Serial Controller (SSC) User Interface Register Mapping Register Control Register Clock Mode Register Reserved Reserved Receive Clock Mode Register Receive Frame Mode Register Transmit Clock Mode Register Transmit Frame Mode Register Receive Holding Register Transmit Holding Register Reserved Reserved Receive Sync. Holding Register Transmit Sync. Holding Register Receive Compare 0 Register Receive Compare 1 Register Status Register Interrupt Enable Register Interrupt Disable Register Interrupt Mask Register Reserved Reserved for Peripheral Data Controller (PDC) Name SSC_CR SSC_CMR – – SSC_RCMR SSC_RFMR SSC_TCMR SSC_TFMR SSC_RHR SSC_THR – – SSC_RSHR SSC_TSHR SSC_RC0R SSC_RC1R SSC_SR SSC_IER SSC_IDR SSC_IMR – – Access Write Read-write – – Read-write Read-write Read-write Read-write Read Write – – Read Read-write Read-write Read-write Read Write Write Read – – Reset – 0x0 – – 0x0 0x0 0x0 0x0 0x0 – – – 0x0 0x0 0x0 0x0 0x000000CC – – 0x0 – – Table 33-4. Offset 0x0 0x4 0x8 0xC 0x10 0x14 0x18 0x1C 0x20 0x24 0x28 0x2C 0x30 0x34 0x38 0x3C 0x40 0x44 0x48 0x4C 0x50-0xFC 0x100- 0x124 533 6384D–ATARM–04-May-09 33.8.1 Name: SSC Control Register SSC_CR Write-only 30 – 22 – 14 – 6 – 29 – 21 – 13 – 5 – 28 – 20 – 12 – 4 – 27 – 19 – 11 – 3 – 26 – 18 – 10 – 2 – 25 – 17 – 9 TXDIS 1 RXDIS 24 – 16 – 8 TXEN 0 RXEN Access Type: 31 – 23 – 15 SWRST 7 – • RXEN: Receive Enable 0 = No effect. 1 = Enables Receive if RXDIS is not set. • RXDIS: Receive Disable 0 = No effect. 1 = Disables Receive. If a character is currently being received, disables at end of current character reception. • TXEN: Transmit Enable 0 = No effect. 1 = Enables Transmit if TXDIS is not set. • TXDIS: Transmit Disable 0 = No effect. 1 = Disables Transmit. If a character is currently being transmitted, disables at end of current character transmission. • SWRST: Software Reset 0 = No effect. 1 = Performs a software reset. Has priority on any other bit in SSC_CR. 534 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 33.8.2 Name: SSC Clock Mode Register SSC_CMR Read-write 30 – 22 – 14 – 6 29 – 21 – 13 – 5 28 – 20 – 12 – 4 DIV 27 – 19 – 11 26 – 18 – 10 DIV 3 2 1 0 25 – 17 – 9 24 – 16 – 8 Access Type: 31 – 23 – 15 – 7 • DIV: Clock Divider 0 = The Clock Divider is not active. Any Other Value: The Divided Clock equals the Master Clock divided by 2 times DIV. The maximum bit rate is MCK/2. The minimum bit rate is MCK/2 x 4095 = MCK/8190. 535 6384D–ATARM–04-May-09 33.8.3 Name: SSC Receive Clock Mode Register SSC_RCMR Read-write 30 29 28 PERIOD 27 26 25 24 Access Type: 31 23 22 21 20 STTDLY 19 18 17 16 15 – 7 CKG 14 – 6 13 – 5 CKI 12 STOP 4 11 10 START 9 8 3 CKO 2 1 CKS 0 • CKS: Receive Clock Selection CKS 0x0 0x1 0x2 0x3 Selected Receive Clock Divided Clock TK Clock signal RK pin Reserved • CKO: Receive Clock Output Mode Selection CKO 0x0 0x1 0x2 0x3-0x7 Receive Clock Output Mode None Continuous Receive Clock Receive Clock only during data transfers Reserved RK pin Input-only Output Output • CKI: Receive Clock Inversion 0 = The data inputs (Data and Frame Sync signals) are sampled on Receive Clock falling edge. The Frame Sync signal output is shifted out on Receive Clock rising edge. 1 = The data inputs (Data and Frame Sync signals) are sampled on Receive Clock rising edge. The Frame Sync signal output is shifted out on Receive Clock falling edge. CKI affects only the Receive Clock and not the output clock signal. 536 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary • CKG: Receive Clock Gating Selection CKG 0x0 0x1 0x2 0x3 Receive Clock Gating None, continuous clock Receive Clock enabled only if RF Low Receive Clock enabled only if RF High Reserved • START: Receive Start Selection START 0x0 0x1 0x2 0x3 0x4 0x5 0x6 0x7 0x8 0x9-0xF Receive Start Continuous, as soon as the receiver is enabled, and immediately after the end of transfer of the previous data. Transmit start Detection of a low level on RF signal Detection of a high level on RF signal Detection of a falling edge on RF signal Detection of a rising edge on RF signal Detection of any level change on RF signal Detection of any edge on RF signal Compare 0 Reserved • STOP: Receive Stop Selection 0 = After completion of a data transfer when starting with a Compare 0, the receiver stops the data transfer and waits for a new compare 0. 1 = After starting a receive with a Compare 0, the receiver operates in a continuous mode until a Compare 1 is detected. • STTDLY: Receive Start Delay If STTDLY is not 0, a delay of STTDLY clock cycles is inserted between the start event and the actual start of reception. When the Receiver is programmed to start synchronously with the Transmitter, the delay is also applied. Note: It is very important that STTDLY be set carefully. If STTDLY must be set, it should be done in relation to TAG (Receive Sync Data) reception. • PERIOD: Receive Period Divider Selection This field selects the divider to apply to the selected Receive Clock in order to generate a new Frame Sync Signal. If 0, no PERIOD signal is generated. If not 0, a PERIOD signal is generated each 2 x (PERIOD+1) Receive Clock. 537 6384D–ATARM–04-May-09 33.8.4 Name: SSC Receive Frame Mode Register SSC_RFMR Read-write 30 FSLEN_EXT 22 29 FSLEN_EXT 21 FSOS 13 – 5 LOOP 28 FSLEN_EXT Access Type: 31 FSLEN_EXT 23 – 15 – 7 MSBF 27 – 19 26 – 18 FSLEN 25 – 17 24 FSEDGE 16 20 14 – 6 – 12 – 4 11 10 DATNB 9 8 3 2 DATLEN 1 0 • DATLEN: Data Length 0 = Forbidden value (1-bit data length not supported). Any other value: The bit stream contains DATLEN + 1 data bits. Moreover, it defines the transfer size performed by the PDC2 assigned to the Receiver. If DATLEN is lower or equal to 7, data transfers are in bytes. If DATLEN is between 8 and 15 (included), half-words are transferred, and for any other value, 32-bit words are transferred. • LOOP: Loop Mode 0 = Normal operating mode. 1 = RD is driven by TD, RF is driven by TF and TK drives RK. • MSBF: Most Significant Bit First 0 = The lowest significant bit of the data register is sampled first in the bit stream. 1 = The most significant bit of the data register is sampled first in the bit stream. • DATNB: Data Number per Frame This field defines the number of data words to be received after each transfer start, which is equal to (DATNB + 1). • FSLEN: Receive Frame Sync Length This field defines the number of bits sampled and stored in the Receive Sync Data Register. When this mode is selected by the START field in the Receive Clock Mode Register, it also determines the length of the sampled data to be compared to the Compare 0 or Compare 1 register. This field is used with FSLEN_EXT to determine the pulse length of the Receive Frame Sync signal. Pulse length is equal to FSLEN + (FSLEN_EXT * 16) + 1 Receive Clock periods. 538 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary • FSOS: Receive Frame Sync Output Selection FSOS 0x0 0x1 0x2 0x3 0x4 0x5 0x6-0x7 Selected Receive Frame Sync Signal None Negative Pulse Positive Pulse Driven Low during data transfer Driven High during data transfer Toggling at each start of data transfer Reserved RF Pin Input-only Output Output Output Output Output Undefined • FSEDGE: Frame Sync Edge Detection Determines which edge on Frame Sync will generate the interrupt RXSYN in the SSC Status Register. FSEDGE 0x0 0x1 Frame Sync Edge Detection Positive Edge Detection Negative Edge Detection • FSLEN_EXT: FSLEN Field Extension Extends FSLEN field. For details, refer to FSLEN bit description on page 538. 539 6384D–ATARM–04-May-09 33.8.5 Name: SSC Transmit Clock Mode Register SSC_TCMR Read-write 30 29 28 PERIOD 27 26 25 24 Access Type: 31 23 22 21 20 STTDLY 19 18 17 16 15 – 7 CKG 14 – 6 13 – 5 CKI 12 – 4 11 10 START 9 8 3 CKO 2 1 CKS 0 • CKS: Transmit Clock Selection CKS 0x0 0x1 0x2 0x3 Selected Transmit Clock Divided Clock RK Clock signal TK Pin Reserved • CKO: Transmit Clock Output Mode Selection CKO 0x0 0x1 0x2 0x3-0x7 Transmit Clock Output Mode None Continuous Transmit Clock Transmit Clock only during data transfers Reserved TK pin Input-only Output Output • CKI: Transmit Clock Inversion 0 = The data outputs (Data and Frame Sync signals) are shifted out on Transmit Clock falling edge. The Frame sync signal input is sampled on Transmit clock rising edge. 1 = The data outputs (Data and Frame Sync signals) are shifted out on Transmit Clock rising edge. The Frame sync signal input is sampled on Transmit clock falling edge. CKI affects only the Transmit Clock and not the output clock signal. 540 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary • CKG: Transmit Clock Gating Selection CKG 0x0 0x1 0x2 0x3 Transmit Clock Gating None, continuous clock Transmit Clock enabled only if TF Low Transmit Clock enabled only if TF High Reserved • START: Transmit Start Selection START 0x0 0x1 0x2 0x3 0x4 0x5 0x6 0x7 0x8 - 0xF Transmit Start Continuous, as soon as a word is written in the SSC_THR Register (if Transmit is enabled), and immediately after the end of transfer of the previous data. Receive start Detection of a low level on TF signal Detection of a high level on TF signal Detection of a falling edge on TF signal Detection of a rising edge on TF signal Detection of any level change on TF signal Detection of any edge on TF signal Reserved • STTDLY: Transmit Start Delay If STTDLY is not 0, a delay of STTDLY clock cycles is inserted between the start event and the actual start of transmission of data. When the Transmitter is programmed to start synchronously with the Receiver, the delay is also applied. Note: STTDLY must be set carefully. If STTDLY is too short in respect to TAG (Transmit Sync Data) emission, data is emitted instead of the end of TAG. • PERIOD: Transmit Period Divider Selection This field selects the divider to apply to the selected Transmit Clock to generate a new Frame Sync Signal. If 0, no period signal is generated. If not 0, a period signal is generated at each 2 x (PERIOD+1) Transmit Clock. 541 6384D–ATARM–04-May-09 33.8.6 Name: SSC Transmit Frame Mode Register SSC_TFMR Read-write 30 FSLEN_EXT 22 29 FSLEN_EXT 21 FSOS 13 – 5 DATDEF 28 FSLEN_EXT Access Type: 31 FSLEN_EXT 23 FSDEN 15 – 7 MSBF 27 – 19 26 – 18 FSLEN 25 – 17 24 FSEDGE 16 20 14 – 6 – 12 – 4 11 10 DATNB 9 8 3 2 DATLEN 1 0 • DATLEN: Data Length 0 = Forbidden value (1-bit data length not supported). Any other value: The bit stream contains DATLEN + 1 data bits. Moreover, it defines the transfer size performed by the PDC2 assigned to the Transmit. If DATLEN is lower or equal to 7, data transfers are bytes, if DATLEN is between 8 and 15 (included), half-words are transferred, and for any other value, 32-bit words are transferred. • DATDEF: Data Default Value This bit defines the level driven on the TD pin while out of transmission. Note that if the pin is defined as multi-drive by the PIO Controller, the pin is enabled only if the SCC TD output is 1. • MSBF: Most Significant Bit First 0 = The lowest significant bit of the data register is shifted out first in the bit stream. 1 = The most significant bit of the data register is shifted out first in the bit stream. • DATNB: Data Number per frame This field defines the number of data words to be transferred after each transfer start, which is equal to (DATNB +1). • FSLEN: Transmit Frame Sync Length This field defines the length of the Transmit Frame Sync signal and the number of bits shifted out from the Transmit Sync Data Register if FSDEN is 1. This field is used with FSLEN_EXT to determine the pulse length of the Transmit Frame Sync signal. Pulse length is equal to FSLEN + (FSLEN_EXT * 16) + 1 Transmit Clock periods. 542 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary • FSOS: Transmit Frame Sync Output Selection FSOS 0x0 0x1 0x2 0x3 0x4 0x5 0x6-0x7 Selected Transmit Frame Sync Signal None Negative Pulse Positive Pulse Driven Low during data transfer Driven High during data transfer Toggling at each start of data transfer Reserved TF Pin Input-only Output Output Output Output Output Undefined • FSDEN: Frame Sync Data Enable 0 = The TD line is driven with the default value during the Transmit Frame Sync signal. 1 = SSC_TSHR value is shifted out during the transmission of the Transmit Frame Sync signal. • FSEDGE: Frame Sync Edge Detection Determines which edge on frame sync will generate the interrupt TXSYN (Status Register). FSEDGE 0x0 0x1 Frame Sync Edge Detection Positive Edge Detection Negative Edge Detection • FSLEN_EXT: FSLEN Field Extension Extends FSLEN field. For details, refer to FSLEN bit description on page 542. 543 6384D–ATARM–04-May-09 33.8.7 Name: SSC Receive Holding Register SSC_RHR Read-only 30 29 28 RDAT 27 26 25 24 Access Type: 31 23 22 21 20 RDAT 19 18 17 16 15 14 13 12 RDAT 11 10 9 8 7 6 5 4 RDAT 3 2 1 0 • RDAT: Receive Data Right aligned regardless of the number of data bits defined by DATLEN in SSC_RFMR. 33.8.8 Name: SSC Transmit Holding Register SSC_THR Write-only 30 29 28 TDAT 27 26 25 24 Access Type: 31 23 22 21 20 TDAT 19 18 17 16 15 14 13 12 TDAT 11 10 9 8 7 6 5 4 TDAT 3 2 1 0 • TDAT: Transmit Data Right aligned regardless of the number of data bits defined by DATLEN in SSC_TFMR. 544 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 33.8.9 Name: SSC Receive Synchronization Holding Register SSC_RSHR Read-only 30 – 22 – 14 29 – 21 – 13 28 – 20 – 12 RSDAT 7 6 5 4 RSDAT 3 2 1 0 27 – 19 – 11 26 – 18 – 10 25 – 17 – 9 24 – 16 – 8 Access Type: 31 – 23 – 15 • RSDAT: Receive Synchronization Data 33.8.10 Name: SSC Transmit Synchronization Holding Register SSC_TSHR Read-write 30 – 22 – 14 29 – 21 – 13 28 – 20 – 12 TSDAT 27 – 19 – 11 26 – 18 – 10 25 – 17 – 9 24 – 16 – 8 Access Type: 31 – 23 – 15 7 6 5 4 TSDAT 3 2 1 0 • TSDAT: Transmit Synchronization Data 545 6384D–ATARM–04-May-09 33.8.11 Name: SSC Receive Compare 0 Register SSC_RC0R Read-write 30 – 22 – 14 29 – 21 – 13 28 – 20 – 12 CP0 27 – 19 – 11 26 – 18 – 10 25 – 17 – 9 24 – 16 – 8 Access Type: 31 – 23 – 15 7 6 5 4 CP0 3 2 1 0 • CP0: Receive Compare Data 0 33.8.12 Name: SSC Receive Compare 1 Register SSC_RC1R Read-write 30 – 22 – 14 29 – 21 – 13 28 – 20 – 12 CP1 27 – 19 – 11 26 – 18 – 10 25 – 17 – 9 24 – 16 – 8 Access Type: 31 – 23 – 15 7 6 5 4 CP1 3 2 1 0 • CP1: Receive Compare Data 1 546 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 33.8.13 Name: SSC Status Register SSC_SR Read-only 30 – 22 – 14 – 6 ENDRX 29 – 21 – 13 – 5 OVRUN 28 – 20 – 12 – 4 RXRDY 27 – 19 – 11 RXSYN 3 TXBUFE 26 – 18 – 10 TXSYN 2 ENDTX 25 – 17 RXEN 9 CP1 1 TXEMPTY 24 – 16 TXEN 8 CP0 0 TXRDY Access Type: 31 – 23 – 15 – 7 RXBUFF • TXRDY: Transmit Ready 0 = Data has been loaded in SSC_THR and is waiting to be loaded in the Transmit Shift Register (TSR). 1 = SSC_THR is empty. • TXEMPTY: Transmit Empty 0 = Data remains in SSC_THR or is currently transmitted from TSR. 1 = Last data written in SSC_THR has been loaded in TSR and last data loaded in TSR has been transmitted. • ENDTX: End of Transmission 0 = The register SSC_TCR has not reached 0 since the last write in SSC_TCR or SSC_TNCR. 1 = The register SSC_TCR has reached 0 since the last write in SSC_TCR or SSC_TNCR. • TXBUFE: Transmit Buffer Empty 0 = SSC_TCR or SSC_TNCR have a value other than 0. 1 = Both SSC_TCR and SSC_TNCR have a value of 0. • RXRDY: Receive Ready 0 = SSC_RHR is empty. 1 = Data has been received and loaded in SSC_RHR. • OVRUN: Receive Overrun 0 = No data has been loaded in SSC_RHR while previous data has not been read since the last read of the Status Register. 1 = Data has been loaded in SSC_RHR while previous data has not yet been read since the last read of the Status Register. • ENDRX: End of Reception 0 = Data is written on the Receive Counter Register or Receive Next Counter Register. 1 = End of PDC transfer when Receive Counter Register has arrived at zero. 547 6384D–ATARM–04-May-09 • RXBUFF: Receive Buffer Full 0 = SSC_RCR or SSC_RNCR have a value other than 0. 1 = Both SSC_RCR and SSC_RNCR have a value of 0. • CP0: Compare 0 0 = A compare 0 has not occurred since the last read of the Status Register. 1 = A compare 0 has occurred since the last read of the Status Register. • CP1: Compare 1 0 = A compare 1 has not occurred since the last read of the Status Register. 1 = A compare 1 has occurred since the last read of the Status Register. • TXSYN: Transmit Sync 0 = A Tx Sync has not occurred since the last read of the Status Register. 1 = A Tx Sync has occurred since the last read of the Status Register. • RXSYN: Receive Sync 0 = An Rx Sync has not occurred since the last read of the Status Register. 1 = An Rx Sync has occurred since the last read of the Status Register. • TXEN: Transmit Enable 0 = Transmit is disabled. 1 = Transmit is enabled. • RXEN: Receive Enable 0 = Receive is disabled. 1 = Receive is enabled. 548 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 33.8.14 Name: SSC Interrupt Enable Register SSC_IER Write-only 30 – 22 – 14 – 6 ENDRX 29 – 21 – 13 – 5 OVRUN 28 – 20 – 12 – 4 RXRDY 27 – 19 – 11 RXSYN 3 TXBUFE 26 – 18 – 10 TXSYN 2 ENDTX 25 – 17 – 9 CP1 1 TXEMPTY 24 – 16 – 8 CP0 0 TXRDY Access Type: 31 – 23 – 15 – 7 RXBUFF • TXRDY: Transmit Ready Interrupt Enable 0 = No effect. 1 = Enables the Transmit Ready Interrupt. • TXEMPTY: Transmit Empty Interrupt Enable 0 = No effect. 1 = Enables the Transmit Empty Interrupt. • ENDTX: End of Transmission Interrupt Enable 0 = No effect. 1 = Enables the End of Transmission Interrupt. • TXBUFE: Transmit Buffer Empty Interrupt Enable 0 = No effect. 1 = Enables the Transmit Buffer Empty Interrupt • RXRDY: Receive Ready Interrupt Enable 0 = No effect. 1 = Enables the Receive Ready Interrupt. • OVRUN: Receive Overrun Interrupt Enable 0 = No effect. 1 = Enables the Receive Overrun Interrupt. • ENDRX: End of Reception Interrupt Enable 0 = No effect. 1 = Enables the End of Reception Interrupt. 549 6384D–ATARM–04-May-09 • RXBUFF: Receive Buffer Full Interrupt Enable 0 = No effect. 1 = Enables the Receive Buffer Full Interrupt. • CP0: Compare 0 Interrupt Enable 0 = No effect. 1 = Enables the Compare 0 Interrupt. • CP1: Compare 1 Interrupt Enable 0 = No effect. 1 = Enables the Compare 1 Interrupt. • TXSYN: Tx Sync Interrupt Enable 0 = No effect. 1 = Enables the Tx Sync Interrupt. • RXSYN: Rx Sync Interrupt Enable 0 = No effect. 1 = Enables the Rx Sync Interrupt. 550 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 33.8.15 Name: SSC Interrupt Disable Register SSC_IDR Write-only 30 – 22 – 14 – 6 ENDRX 29 – 21 – 13 – 5 OVRUN 28 – 20 – 12 – 4 RXRDY 27 – 19 – 11 RXSYN 3 TXBUFE 26 – 18 – 10 TXSYN 2 ENDTX 25 – 17 – 9 CP1 1 TXEMPTY 24 – 16 – 8 CP0 0 TXRDY Access Type: 31 – 23 – 15 – 7 RXBUFF • TXRDY: Transmit Ready Interrupt Disable 0 = No effect. 1 = Disables the Transmit Ready Interrupt. • TXEMPTY: Transmit Empty Interrupt Disable 0 = No effect. 1 = Disables the Transmit Empty Interrupt. • ENDTX: End of Transmission Interrupt Disable 0 = No effect. 1 = Disables the End of Transmission Interrupt. • TXBUFE: Transmit Buffer Empty Interrupt Disable 0 = No effect. 1 = Disables the Transmit Buffer Empty Interrupt. • RXRDY: Receive Ready Interrupt Disable 0 = No effect. 1 = Disables the Receive Ready Interrupt. • OVRUN: Receive Overrun Interrupt Disable 0 = No effect. 1 = Disables the Receive Overrun Interrupt. • ENDRX: End of Reception Interrupt Disable 0 = No effect. 1 = Disables the End of Reception Interrupt. 551 6384D–ATARM–04-May-09 • RXBUFF: Receive Buffer Full Interrupt Disable 0 = No effect. 1 = Disables the Receive Buffer Full Interrupt. • CP0: Compare 0 Interrupt Disable 0 = No effect. 1 = Disables the Compare 0 Interrupt. • CP1: Compare 1 Interrupt Disable 0 = No effect. 1 = Disables the Compare 1 Interrupt. • TXSYN: Tx Sync Interrupt Enable 0 = No effect. 1 = Disables the Tx Sync Interrupt. • RXSYN: Rx Sync Interrupt Enable 0 = No effect. 1 = Disables the Rx Sync Interrupt. 552 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 33.8.16 Name: SSC Interrupt Mask Register SSC_IMR Read-only 30 – 22 – 14 – 6 ENDRX 29 – 21 – 13 – 5 OVRUN 28 – 20 – 12 – 4 RXRDY 27 – 19 – 11 RXSYN 3 TXBUFE 26 – 18 – 10 TXSYN 2 ENDTX 25 – 17 – 9 CP1 1 TXEMPTY 24 – 16 – 8 CP0 0 TXRDY Access Type: 31 – 23 – 15 – 7 RXBUF • TXRDY: Transmit Ready Interrupt Mask 0 = The Transmit Ready Interrupt is disabled. 1 = The Transmit Ready Interrupt is enabled. • TXEMPTY: Transmit Empty Interrupt Mask 0 = The Transmit Empty Interrupt is disabled. 1 = The Transmit Empty Interrupt is enabled. • ENDTX: End of Transmission Interrupt Mask 0 = The End of Transmission Interrupt is disabled. 1 = The End of Transmission Interrupt is enabled. • TXBUFE: Transmit Buffer Empty Interrupt Mask 0 = The Transmit Buffer Empty Interrupt is disabled. 1 = The Transmit Buffer Empty Interrupt is enabled. • RXRDY: Receive Ready Interrupt Mask 0 = The Receive Ready Interrupt is disabled. 1 = The Receive Ready Interrupt is enabled. • OVRUN: Receive Overrun Interrupt Mask 0 = The Receive Overrun Interrupt is disabled. 1 = The Receive Overrun Interrupt is enabled. • ENDRX: End of Reception Interrupt Mask 0 = The End of Reception Interrupt is disabled. 1 = The End of Reception Interrupt is enabled. 553 6384D–ATARM–04-May-09 • RXBUFF: Receive Buffer Full Interrupt Mask 0 = The Receive Buffer Full Interrupt is disabled. 1 = The Receive Buffer Full Interrupt is enabled. • CP0: Compare 0 Interrupt Mask 0 = The Compare 0 Interrupt is disabled. 1 = The Compare 0 Interrupt is enabled. • CP1: Compare 1 Interrupt Mask 0 = The Compare 1 Interrupt is disabled. 1 = The Compare 1 Interrupt is enabled. • TXSYN: Tx Sync Interrupt Mask 0 = The Tx Sync Interrupt is disabled. 1 = The Tx Sync Interrupt is enabled. • RXSYN: Rx Sync Interrupt Mask 0 = The Rx Sync Interrupt is disabled. 1 = The Rx Sync Interrupt is enabled. 554 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 34. Timer Counter (TC) 34.1 Overview The Timer Counter (TC) includes three identical 16-bit Timer Counter channels. Each channel can be independently programmed to perform a wide range of functions including frequency measurement, event counting, interval measurement, pulse generation, delay timing and pulse width modulation. Each channel has three external clock inputs, five internal clock inputs and two multi-purpose input/output signals which can be configured by the user. Each channel drives an internal interrupt signal which can be programmed to generate processor interrupts. The Timer Counter block has two global registers which act upon all three TC channels. The Block Control Register allows the three channels to be started simultaneously with the same instruction. The Block Mode Register defines the external clock inputs for each channel, allowing them to be chained. Table 34-1 gives the assignment of the device Timer Counter clock inputs common to Timer Counter 0 to 2 Table 34-1. Name Timer Counter Clock Assignment Definition MCK/2 MCK/8 MCK/32 MCK/128 SLCK TIMER_CLOCK1 TIMER_CLOCK2 TIMER_CLOCK3 TIMER_CLOCK4 TIMER_CLOCK5 555 6384D–ATARM–04-May-09 34.2 Block Diagram Figure 34-1. Timer Counter Block Diagram Parallel I/O Controller TCLK0 TIMER_CLOCK2 TIMER_CLOCK1 TIOA1 TIMER_CLOCK3 TCLK0 TCLK1 TCLK2 TIOA0 TIOB0 TIOA2 TCLK1 XC0 XC1 XC2 TC0XC0S Timer/Counter Channel 0 TIOA TIOA0 TIOB TIMER_CLOCK4 TIMER_CLOCK5 TCLK2 TIOB0 SYNC INT0 TCLK0 TCLK1 TIOA0 TIOA2 TCLK2 XC0 XC1 XC2 TC1XC1S SYNC Timer/Counter Channel 1 TIOA TIOA1 TIOB TIOB1 INT1 TIOA1 TIOB1 TCLK0 TCLK1 TCLK2 TIOA0 TIOA1 XC0 XC1 XC2 TC2XC2S Timer/Counter Channel 2 TIOA TIOA2 TIOB TIOB2 SYNC TIOA2 TIOB2 INT2 Timer Counter Advanced Interrupt Controller Table 34-2. Signal Name Description Signal Name XC0, XC1, XC2 TIOA Description External Clock Inputs Capture Mode: Timer Counter Input Waveform Mode: Timer Counter Output Capture Mode: Timer Counter Input Waveform Mode: Timer Counter Input/Output Interrupt Signal Output Synchronization Input Signal Block/Channel Channel Signal TIOB INT SYNC 556 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 34.3 Pin Name List Table 34-3. Pin Name TCLK0-TCLK2 TIOA0-TIOA2 TIOB0-TIOB2 TC pin list Description External Clock Input I/O Line A I/O Line B Type Input I/O I/O 34.4 34.4.1 Product Dependencies I/O Lines The pins used for interfacing the compliant external devices may be multiplexed with PIO lines. The programmer must first program the PIO controllers to assign the TC pins to their peripheral functions. 34.4.2 Power Management The TC is clocked through the Power Management Controller (PMC), thus the programmer must first configure the PMC to enable the Timer Counter clock. Interrupt The TC has an interrupt line connected to the Advanced Interrupt Controller (AIC). Handling the TC interrupt requires programming the AIC before configuring the TC. 34.4.3 557 6384D–ATARM–04-May-09 34.5 34.5.1 Functional Description TC Description The three channels of the Timer Counter are independent and identical in operation. The registers for channel programming are listed in Table 34-4 on page 571. 16-bit Counter Each channel is organized around a 16-bit counter. The value of the counter is incremented at each positive edge of the selected clock. When the counter has reached the value 0xFFFF and passes to 0x0000, an overflow occurs and the COVFS bit in TC_SR (Status Register) is set. The current value of the counter is accessible in real time by reading the Counter Value Register, TC_CV. The counter can be reset by a trigger. In this case, the counter value passes to 0x0000 on the next valid edge of the selected clock. 34.5.2 34.5.3 Clock Selection At block level, input clock signals of each channel can either be connected to the external inputs TCLK0, TCLK1 or TCLK2, or be connected to the internal I/O signals TIOA0, TIOA1 or TIOA2 for chaining by programming the TC_BMR (Block Mode). See Figure 34-2 on page 559. Each channel can independently select an internal or external clock source for its counter: • • Internal clock signals: TIMER_CLOCK1, TIMER_CLOCK2, TIMER_CLOCK3, TIMER_CLOCK4, TIMER_CLOCK5 External clock signals: XC0, XC1 or XC2 This selection is made by the TCCLKS bits in the TC Channel Mode Register. The selected clock can be inverted with the CLKI bit in TC_CMR. This allows counting on the opposite edges of the clock. The burst function allows the clock to be validated when an external signal is high. The BURST parameter in the Mode Register defines this signal (none, XC0, XC1, XC2). See Figure 34-3 on page 559 Note: In all cases, if an external clock is used, the duration of each of its levels must be longer than the master clock period. The external clock frequency must be at least 2.5 times lower than the master clock 558 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Figure 34-2. Clock Chaining Selection TC0XC0S Timer/Counter Channel 0 TIOA1 TIOA2 XC0 XC1 = TCLK1 XC2 = TCLK2 TIOB0 TIOA0 TCLK0 SYNC TC1XC1S Timer/Counter Channel 1 TCLK1 TIOA0 TIOA2 XC0 = TCLK2 XC1 XC2 = TCLK2 TIOB1 TIOA1 SYNC TC2XC2S Timer/Counter Channel 2 XC0 = TCLK0 TIOA2 TCLK2 TIOA0 TIOA1 XC1 = TCLK1 XC2 TIOB2 SYNC Figure 34-3. Clock Selection TCCLKS TIMER_CLOCK1 TIMER_CLOCK2 TIMER_CLOCK3 TIMER_CLOCK4 TIMER_CLOCK5 XC0 XC1 XC2 CLKI Selected Clock BURST 1 559 6384D–ATARM–04-May-09 34.5.4 Clock Control The clock of each counter can be controlled in two different ways: it can be enabled/disabled and started/stopped. See Figure 34-4. • The clock can be enabled or disabled by the user with the CLKEN and the CLKDIS commands in the Control Register. In Capture Mode it can be disabled by an RB load event if LDBDIS is set to 1 in TC_CMR. In Waveform Mode, it can be disabled by an RC Compare event if CPCDIS is set to 1 in TC_CMR. When disabled, the start or the stop actions have no effect: only a CLKEN command in the Control Register can re-enable the clock. When the clock is enabled, the CLKSTA bit is set in the Status Register. The clock can also be started or stopped: a trigger (software, synchro, external or compare) always starts the clock. The clock can be stopped by an RB load event in Capture Mode (LDBSTOP = 1 in TC_CMR) or a RC compare event in Waveform Mode (CPCSTOP = 1 in TC_CMR). The start and the stop commands have effect only if the clock is enabled. • Figure 34-4. Clock Control Selected Clock Trigger CLKSTA CLKEN CLKDIS Q Q S R S R Counter Clock Stop Event Disable Event 34.5.5 TC Operating Modes Each channel can independently operate in two different modes: • • Capture Mode provides measurement on signals. Waveform Mode provides wave generation. The TC Operating Mode is programmed with the WAVE bit in the TC Channel Mode Register. In Capture Mode, TIOA and TIOB are configured as inputs. In Waveform Mode, TIOA is always configured to be an output and TIOB is an output if it is not selected to be the external trigger. 34.5.6 Trigger A trigger resets the counter and starts the counter clock. Three types of triggers are common to both modes, and a fourth external trigger is available to each mode. The following triggers are common to both modes: 560 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary • • Software Trigger: Each channel has a software trigger, available by setting SWTRG in TC_CCR. SYNC: Each channel has a synchronization signal SYNC. When asserted, this signal has the same effect as a software trigger. The SYNC signals of all channels are asserted simultaneously by writing TC_BCR (Block Control) with SYNC set. Compare RC Trigger: RC is implemented in each channel and can provide a trigger when the counter value matches the RC value if CPCTRG is set in TC_CMR. • The channel can also be configured to have an external trigger. In Capture Mode, the external trigger signal can be selected between TIOA and TIOB. In Waveform Mode, an external event can be programmed on one of the following signals: TIOB, XC0, XC1 or XC2. This external event can then be programmed to perform a trigger by setting ENETRG in TC_CMR. If an external trigger is used, the duration of the pulses must be longer than the master clock period in order to be detected. Regardless of the trigger used, it will be taken into account at the following active edge of the selected clock. This means that the counter value can be read differently from zero just after a trigger, especially when a low frequency signal is selected as the clock. 34.5.7 Capture Operating Mode This mode is entered by clearing the WAVE parameter in TC_CMR (Channel Mode Register). Capture Mode allows the TC channel to perform measurements such as pulse timing, frequency, period, duty cycle and phase on TIOA and TIOB signals which are considered as inputs. Figure 34-5 shows the configuration of the TC channel when programmed in Capture Mode. 34.5.8 Capture Registers A and B Registers A and B (RA and RB) are used as capture registers. This means that they can be loaded with the counter value when a programmable event occurs on the signal TIOA. The LDRA parameter in TC_CMR defines the TIOA edge for the loading of register A, and the LDRB parameter defines the TIOA edge for the loading of Register B. RA is loaded only if it has not been loaded since the last trigger or if RB has been loaded since the last loading of RA. RB is loaded only if RA has been loaded since the last trigger or the last loading of RB. Loading RA or RB before the read of the last value loaded sets the Overrun Error Flag (LOVRS) in TC_SR (Status Register). In this case, the old value is overwritten. 34.5.9 Trigger Conditions In addition to the SYNC signal, the software trigger and the RC compare trigger, an external trigger can be defined. The ABETRG bit in TC_CMR selects TIOA or TIOB input signal as an external trigger. The ETRGEDG parameter defines the edge (rising, falling or both) detected to generate an external trigger. If ETRGEDG = 0 (none), the external trigger is disabled. 561 6384D–ATARM–04-May-09 Figure 34-5. Capture Mode 562 TCCLKS CLKI CLKSTA CLKEN CLKDIS TIMER_CLOCK1 TIMER_CLOCK2 TIMER_CLOCK3 TIMER_CLOCK4 Q Q R S R S TIMER_CLOCK5 XC0 XC1 LDBSTOP BURST LDBDIS XC2 Register C 1 16-bit Counter CLK OVF RESET Trig ABETRG ETRGEDG Edge Detector LDRA LDRB CPCTRG Capture Register A SWTRG AT91SAM9G20 Preliminary Capture Register B Compare RC = CPCS LOVRS LDRAS LDRBS ETRGS COVFS TC1_SR SYNC MTIOB TIOB MTIOA If RA is not loaded or RB is Loaded Edge Detector If RA is Loaded Edge Detector TC1_IMR TIOA Timer/Counter Channel 6384D–ATARM–04-May-09 INT AT91SAM9G20 Preliminary 34.5.10 Waveform Operating Mode Waveform operating mode is entered by setting the WAVE parameter in TC_CMR (Channel Mode Register). In Waveform Operating Mode the TC channel generates 1 or 2 PWM signals with the same frequency and independently programmable duty cycles, or generates different types of one-shot or repetitive pulses. In this mode, TIOA is configured as an output and TIOB is defined as an output if it is not used as an external event (EEVT parameter in TC_CMR). Figure 34-6 shows the configuration of the TC channel when programmed in Waveform Operating Mode. 34.5.11 Waveform Selection Depending on the WAVSEL parameter in TC_CMR (Channel Mode Register), the behavior of TC_CV varies. With any selection, RA, RB and RC can all be used as compare registers. RA Compare is used to control the TIOA output, RB Compare is used to control the TIOB output (if correctly configured) and RC Compare is used to control TIOA and/or TIOB outputs. 563 6384D–ATARM–04-May-09 BURST Register A WAVSEL Register B Edge Detector TIOB TC1_IMR BSWTRG Timer/Counter Channel 6384D–ATARM–04-May-09 INT Output Controller AT91SAM9G20 Preliminary TCCLKS CLKSTA CLKI CLKEN CLKDIS ACPC Register C ASWTRG 1 16-bit Counter CLK RESET OVF Compare RA = Compare RB = Compare RC = SWTRG BCPC Trig BCPB WAVSEL EEVT BEEVT EEVTEDG ENETRG CPCS CPAS CPBS ETRGS COVFS TC1_SR MTIOB SYNC Output Controller 564 Q CPCDIS TIMER_CLOCK1 TIMER_CLOCK2 TIMER_CLOCK3 TIMER_CLOCK4 S R ACPA MTIOA TIMER_CLOCK5 Q R CPCSTOP S XC0 XC1 Figure 34-6. Waveform Mode XC2 AEEVT TIOA TIOB AT91SAM9G20 Preliminary 34.5.11.1 WAVSEL = 00 When WAVSEL = 00, the value of TC_CV is incremented from 0 to 0xFFFF. Once 0xFFFF has been reached, the value of TC_CV is reset. Incrementation of TC_CV starts again and the cycle continues. See Figure 34-7. An external event trigger or a software trigger can reset the value of TC_CV. It is important to note that the trigger may occur at any time. See Figure 34-8. RC Compare cannot be programmed to generate a trigger in this configuration. At the same time, RC Compare can stop the counter clock (CPCSTOP = 1 in TC_CMR) and/or disable the counter clock (CPCDIS = 1 in TC_CMR). Figure 34-7. WAVSEL= 00 without trigger Counter Value 0xFFFF Counter cleared by compare match with 0xFFFF RC RB RA Waveform Examples TIOB Time TIOA 565 6384D–ATARM–04-May-09 Figure 34-8. WAVSEL= 00 with trigger Counter Value 0xFFFF Counter cleared by trigger Counter cleared by compare match with 0xFFFF RC RB RA Waveform Examples TIOB Time TIOA 34.5.11.2 WAVSEL = 10 When WAVSEL = 10, the value of TC_CV is incremented from 0 to the value of RC, then automatically reset on a RC Compare. Once the value of TC_CV has been reset, it is then incremented and so on. See Figure 34-9. It is important to note that TC_CV can be reset at any time by an external event or a software trigger if both are programmed correctly. See Figure 34-10. In addition, RC Compare can stop the counter clock (CPCSTOP = 1 in TC_CMR) and/or disable the counter clock (CPCDIS = 1 in TC_CMR). Figure 34-9. WAVSEL = 10 Without Trigger Counter Value 0xFFFF Counter cleared by compare match with RC RC RB RA Waveform Examples TIOB Time TIOA 566 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Figure 34-10. WAVSEL = 10 With Trigger Counter Value 0xFFFF Counter cleared by compare match with RC RC RB Counter cleared by trigger RA Waveform Examples TIOB Time TIOA 34.5.11.3 WAVSEL = 01 When WAVSEL = 01, the value of TC_CV is incremented from 0 to 0xFFFF. Once 0xFFFF is reached, the value of TC_CV is decremented to 0, then re-incremented to 0xFFFF and so on. See Figure 34-11. A trigger such as an external event or a software trigger can modify TC_CV at any time. If a trigger occurs while TC_CV is incrementing, TC_CV then decrements. If a trigger is received while TC_CV is decrementing, TC_CV then increments. See Figure 34-12. RC Compare cannot be programmed to generate a trigger in this configuration. At the same time, RC Compare can stop the counter clock (CPCSTOP = 1) and/or disable the counter clock (CPCDIS = 1). 567 6384D–ATARM–04-May-09 Figure 34-11. WAVSEL = 01 Without Trigger Counter Value 0xFFFF Counter decremented by compare match with 0xFFFF RC RB RA Waveform Examples TIOB Time TIOA Figure 34-12. WAVSEL = 01 With Trigger Counter Value 0xFFFF Counter decremented by trigger RC RB Counter decremented by compare match with 0xFFFF Counter incremented by trigger RA Waveform Examples TIOB Time TIOA 34.5.11.4 WAVSEL = 11 When WAVSEL = 11, the value of TC_CV is incremented from 0 to RC. Once RC is reached, the value of TC_CV is decremented to 0, then re-incremented to RC and so on. See Figure 34-13. A trigger such as an external event or a software trigger can modify TC_CV at any time. If a trigger occurs while TC_CV is incrementing, TC_CV then decrements. If a trigger is received while TC_CV is decrementing, TC_CV then increments. See Figure 34-14. RC Compare can stop the counter clock (CPCSTOP = 1) and/or disable the counter clock (CPCDIS = 1). 568 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Figure 34-13. WAVSEL = 11 Without Trigger Counter Value 0xFFFF Counter decremented by compare match with RC RC RB RA Waveform Examples TIOB Time TIOA Figure 34-14. WAVSEL = 11 With Trigger Counter Value 0xFFFF Counter decremented by compare match with RC RC RB Counter decremented by trigger Counter incremented by trigger RA Waveform Examples TIOB Time TIOA 569 6384D–ATARM–04-May-09 34.5.12 External Event/Trigger Conditions An external event can be programmed to be detected on one of the clock sources (XC0, XC1, XC2) or TIOB. The external event selected can then be used as a trigger. The EEVT parameter in TC_CMR selects the external trigger. The EEVTEDG parameter defines the trigger edge for each of the possible external triggers (rising, falling or both). If EEVTEDG is cleared (none), no external event is defined. If TIOB is defined as an external event signal (EEVT = 0), TIOB is no longer used as an output and the compare register B is not used to generate waveforms and subsequently no IRQs. In this case the TC channel can only generate a waveform on TIOA. When an external event is defined, it can be used as a trigger by setting bit ENETRG in TC_CMR. As in Capture Mode, the SYNC signal and the software trigger are also available as triggers. RC Compare can also be used as a trigger depending on the parameter WAVSEL. 34.5.13 Output Controller The output controller defines the output level changes on TIOA and TIOB following an event. TIOB control is used only if TIOB is defined as output (not as an external event). The following events control TIOA and TIOB: software trigger, external event and RC compare. RA compare controls TIOA and RB compare controls TIOB. Each of these events can be programmed to set, clear or toggle the output as defined in the corresponding parameter in TC_CMR. 570 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 34.6 Timer Counter (TC) User Interface Register Mapping Offset(1) 0x00 + channel * 0x40 + 0x00 0x00 + channel * 0x40 + 0x04 0x00 + channel * 0x40 + 0x08 0x00 + channel * 0x40 + 0x0C 0x00 + channel * 0x40 + 0x10 0x00 + channel * 0x40 + 0x14 0x00 + channel * 0x40 + 0x18 0x00 + channel * 0x40 + 0x1C 0x00 + channel * 0x40 + 0x20 0x00 + channel * 0x40 + 0x24 0x00 + channel * 0x40 + 0x28 0x00 + channel * 0x40 + 0x2C 0xC0 0xC4 0xFC Notes: 2. Read-only if WAVE = 0 Register Channel Control Register Channel Mode Register Reserved Reserved Counter Value Register A Register B Register C Status Register Interrupt Enable Register Interrupt Disable Register Interrupt Mask Register Block Control Register Block Mode Register Reserved TC_CV TC_RA TC_RB TC_RC TC_SR TC_IER TC_IDR TC_IMR TC_BCR TC_BMR – Read-only Read-write Read-write (2) (2) Table 34-4. Name TC_CCR TC_CMR Access Write-only Read-write Reset – 0 0 0 0 0 0 – – 0 – 0 – Read-write Read-only Write-only Write-only Read-only Write-only Read-write – 1. Channel index ranges from 0 to 2. 571 6384D–ATARM–04-May-09 34.6.1 TC Block Control Register Register Name:TC_BCR Access Type:Write-only 31 – 23 – 15 – 7 – 30 – 22 – 14 – 6 – 29 – 21 – 13 – 5 – 28 – 20 – 12 – 4 – 27 – 19 – 11 – 3 – 26 – 18 – 10 – 2 – 25 – 17 – 9 – 1 – 24 – 16 – 8 – 0 SYNC • SYNC: Synchro Command 0 = No effect. 1 = Asserts the SYNC signal which generates a software trigger simultaneously for each of the channels. 572 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 34.6.2 TC Block Mode Register Register Name:TC_BMR Access Type:Read-write 31 – 23 – 15 – 7 – 30 – 22 – 14 – 6 – 29 – 21 – 13 – 5 TC2XC2S 28 – 20 – 12 – 4 27 – 19 – 11 – 3 TC1XC1S 26 – 18 – 10 – 2 25 – 17 – 9 – 1 TC0XC0S 24 – 16 – 8 – 0 • TC0XC0S: External Clock Signal 0 Selection TC0XC0S 0 0 1 1 0 1 0 1 Signal Connected to XC0 TCLK0 none TIOA1 TIOA2 • TC1XC1S: External Clock Signal 1 Selection TC1XC1S 0 0 1 1 0 1 0 1 Signal Connected to XC1 TCLK1 none TIOA0 TIOA2 • TC2XC2S: External Clock Signal 2 Selection TC2XC2S 0 0 1 1 0 1 0 1 Signal Connected to XC2 TCLK2 none TIOA0 TIOA1 573 6384D–ATARM–04-May-09 34.6.3 TC Channel Control Register Register Name:TC_CCRx [x=0..2] Access Type:Write-only 31 – 23 – 15 – 7 – 30 – 22 – 14 – 6 – 29 – 21 – 13 – 5 – 28 – 20 – 12 – 4 – 27 – 19 – 11 – 3 – 26 – 18 – 10 – 2 SWTRG 25 – 17 – 9 – 1 CLKDIS 24 – 16 – 8 – 0 CLKEN • CLKEN: Counter Clock Enable Command 0 = No effect. 1 = Enables the clock if CLKDIS is not 1. • CLKDIS: Counter Clock Disable Command 0 = No effect. 1 = Disables the clock. • SWTRG: Software Trigger Command 0 = No effect. 1 = A software trigger is performed: the counter is reset and the clock is started. 574 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 34.6.4 TC Channel Mode Register: Capture Mode Register Name:TC_CMRx [x=0..2] (WAVE = 0) Access Type:Read-write 31 – 23 – 15 WAVE 7 LDBDIS 30 – 22 – 14 CPCTRG 6 LDBSTOP 29 – 21 – 13 – 5 BURST 28 – 20 – 12 – 4 11 – 3 CLKI 27 – 19 LDRB 10 ABETRG 2 1 TCCLKS 9 ETRGEDG 0 26 – 18 25 – 17 LDRA 8 24 – 16 • TCCLKS: Clock Selection TCCLKS 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 Clock Selected TIMER_CLOCK1 TIMER_CLOCK2 TIMER_CLOCK3 TIMER_CLOCK4 TIMER_CLOCK5 XC0 XC1 XC2 • CLKI: Clock Invert 0 = Counter is incremented on rising edge of the clock. 1 = Counter is incremented on falling edge of the clock. • BURST: Burst Signal Selection BURST 0 0 1 1 0 1 0 1 The clock is not gated by an external signal. XC0 is ANDed with the selected clock. XC1 is ANDed with the selected clock. XC2 is ANDed with the selected clock. • LDBSTOP: Counter Clock Stopped with RB Loading 0 = Counter clock is not stopped when RB loading occurs. 1 = Counter clock is stopped when RB loading occurs. 575 6384D–ATARM–04-May-09 • LDBDIS: Counter Clock Disable with RB Loading 0 = Counter clock is not disabled when RB loading occurs. 1 = Counter clock is disabled when RB loading occurs. • ETRGEDG: External Trigger Edge Selection ETRGEDG 0 0 1 1 0 1 0 1 Edge none rising edge falling edge each edge • ABETRG: TIOA or TIOB External Trigger Selection 0 = TIOB is used as an external trigger. 1 = TIOA is used as an external trigger. • CPCTRG: RC Compare Trigger Enable 0 = RC Compare has no effect on the counter and its clock. 1 = RC Compare resets the counter and starts the counter clock. • WAVE 0 = Capture Mode is enabled. 1 = Capture Mode is disabled (Waveform Mode is enabled). • LDRA: RA Loading Selection LDRA 0 0 1 1 0 1 0 1 Edge none rising edge of TIOA falling edge of TIOA each edge of TIOA • LDRB: RB Loading Selection LDRB 0 0 1 1 0 1 0 1 Edge none rising edge of TIOA falling edge of TIOA each edge of TIOA 576 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 34.6.5 TC Channel Mode Register: Waveform Mode Register Name:TC_CMRx [x=0..2] (WAVE = 1) Access Type:Read-write 31 BSWTRG 23 ASWTRG 15 WAVE 7 CPCDIS 6 CPCSTOP 14 WAVSEL 5 BURST 13 22 21 AEEVT 12 ENETRG 4 3 CLKI 11 EEVT 2 1 TCCLKS 30 29 BEEVT 20 19 ACPC 10 9 EEVTEDG 0 28 27 BCPC 18 17 ACPA 8 26 25 BCPB 16 24 • TCCLKS: Clock Selection TCCLKS 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 Clock Selected TIMER_CLOCK1 TIMER_CLOCK2 TIMER_CLOCK3 TIMER_CLOCK4 TIMER_CLOCK5 XC0 XC1 XC2 • CLKI: Clock Invert 0 = Counter is incremented on rising edge of the clock. 1 = Counter is incremented on falling edge of the clock. • BURST: Burst Signal Selection BURST 0 0 1 1 0 1 0 1 The clock is not gated by an external signal. XC0 is ANDed with the selected clock. XC1 is ANDed with the selected clock. XC2 is ANDed with the selected clock. • CPCSTOP: Counter Clock Stopped with RC Compare 0 = Counter clock is not stopped when counter reaches RC. 1 = Counter clock is stopped when counter reaches RC. 577 6384D–ATARM–04-May-09 • CPCDIS: Counter Clock Disable with RC Compare 0 = Counter clock is not disabled when counter reaches RC. 1 = Counter clock is disabled when counter reaches RC. • EEVTEDG: External Event Edge Selection EEVTEDG 0 0 1 1 0 1 0 1 Edge none rising edge falling edge each edge • EEVT: External Event Selection EEVT 0 0 1 1 Note: 0 1 0 1 Signal selected as external event TIOB XC0 XC1 XC2 TIOB Direction input (1) output output output 1. If TIOB is chosen as the external event signal, it is configured as an input and no longer generates waveforms and subsequently no IRQs. • ENETRG: External Event Trigger Enable 0 = The external event has no effect on the counter and its clock. In this case, the selected external event only controls the TIOA output. 1 = The external event resets the counter and starts the counter clock. • WAVSEL: Waveform Selection WAVSEL 0 1 0 1 0 0 1 1 Effect UP mode without automatic trigger on RC Compare UP mode with automatic trigger on RC Compare UPDOWN mode without automatic trigger on RC Compare UPDOWN mode with automatic trigger on RC Compare • WAVE 0 = Waveform Mode is disabled (Capture Mode is enabled). 1 = Waveform Mode is enabled. 578 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary • ACPA: RA Compare Effect on TIOA ACPA 0 0 1 1 0 1 0 1 Effect none set clear toggle • ACPC: RC Compare Effect on TIOA ACPC 0 0 1 1 0 1 0 1 Effect none set clear toggle • AEEVT: External Event Effect on TIOA AEEVT 0 0 1 1 0 1 0 1 Effect none set clear toggle • ASWTRG: Software Trigger Effect on TIOA ASWTRG 0 0 1 1 0 1 0 1 Effect none set clear toggle • BCPB: RB Compare Effect on TIOB BCPB 0 0 1 1 0 1 0 1 Effect none set clear toggle 579 6384D–ATARM–04-May-09 • BCPC: RC Compare Effect on TIOB BCPC 0 0 1 1 0 1 0 1 Effect none set clear toggle • BEEVT: External Event Effect on TIOB BEEVT 0 0 1 1 0 1 0 1 Effect none set clear toggle • BSWTRG: Software Trigger Effect on TIOB BSWTRG 0 0 1 1 0 1 0 1 Effect none set clear toggle 580 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 34.6.6 TC Counter Value Register Register Name:TC_CVx [x=0..2] Access Type:Read-only 31 – 23 – 15 30 – 22 – 14 29 – 21 – 13 28 – 20 – 12 CV 7 6 5 4 CV 3 2 1 0 27 – 19 – 11 26 – 18 – 10 25 – 17 – 9 24 – 16 – 8 • CV: Counter Value CV contains the counter value in real time. 581 6384D–ATARM–04-May-09 34.6.7 TC Register A Register Name:TC_RAx [x=0..2] Access Type:Read-only if WAVE = 0, Read-write if WAVE = 1 31 – 23 – 15 30 – 22 – 14 29 – 21 – 13 28 – 20 – 12 RA 7 6 5 4 RA 3 2 1 0 27 – 19 – 11 26 – 18 – 10 25 – 17 – 9 24 – 16 – 8 • RA: Register A RA contains the Register A value in real time. 582 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 34.6.8 TC Register B Register Name:TC_RBx [x=0..2] Access Type:Read-only if WAVE = 0, Read-write if WAVE = 1 31 – 23 – 15 30 – 22 – 14 29 – 21 – 13 28 – 20 – 12 RB 7 6 5 4 RB 3 2 1 0 27 – 19 – 11 26 – 18 – 10 25 – 17 – 9 24 – 16 – 8 • RB: Register B RB contains the Register B value in real time. 34.6.9 TC Register C Register Name:TC_RCx [x=0..2] Access Type:Read-write 31 – 23 – 15 30 – 22 – 14 29 – 21 – 13 28 – 20 – 12 RC 7 6 5 4 RC 3 2 1 0 27 – 19 – 11 26 – 18 – 10 25 – 17 – 9 24 – 16 – 8 • RC: Register C RC contains the Register C value in real time. 583 6384D–ATARM–04-May-09 34.6.10 TC Status Register Register Name:TC_SRx [x=0..2] Access Type:Read-only 31 – 23 – 15 – 7 ETRGS 30 – 22 – 14 – 6 LDRBS 29 – 21 – 13 – 5 LDRAS 28 – 20 – 12 – 4 CPCS 27 – 19 – 11 – 3 CPBS 26 – 18 MTIOB 10 – 2 CPAS 25 – 17 MTIOA 9 – 1 LOVRS 24 – 16 CLKSTA 8 – 0 COVFS • COVFS: Counter Overflow Status 0 = No counter overflow has occurred since the last read of the Status Register. 1 = A counter overflow has occurred since the last read of the Status Register. • LOVRS: Load Overrun Status 0 = Load overrun has not occurred since the last read of the Status Register or WAVE = 1. 1 = RA or RB have been loaded at least twice without any read of the corresponding register since the last read of the Status Register, if WAVE = 0. • CPAS: RA Compare Status 0 = RA Compare has not occurred since the last read of the Status Register or WAVE = 0. 1 = RA Compare has occurred since the last read of the Status Register, if WAVE = 1. • CPBS: RB Compare Status 0 = RB Compare has not occurred since the last read of the Status Register or WAVE = 0. 1 = RB Compare has occurred since the last read of the Status Register, if WAVE = 1. • CPCS: RC Compare Status 0 = RC Compare has not occurred since the last read of the Status Register. 1 = RC Compare has occurred since the last read of the Status Register. • LDRAS: RA Loading Status 0 = RA Load has not occurred since the last read of the Status Register or WAVE = 1. 1 = RA Load has occurred since the last read of the Status Register, if WAVE = 0. • LDRBS: RB Loading Status 0 = RB Load has not occurred since the last read of the Status Register or WAVE = 1. 1 = RB Load has occurred since the last read of the Status Register, if WAVE = 0. • ETRGS: External Trigger Status 0 = External trigger has not occurred since the last read of the Status Register. 1 = External trigger has occurred since the last read of the Status Register. 584 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary • CLKSTA: Clock Enabling Status 0 = Clock is disabled. 1 = Clock is enabled. • MTIOA: TIOA Mirror 0 = TIOA is low. If WAVE = 0, this means that TIOA pin is low. If WAVE = 1, this means that TIOA is driven low. 1 = TIOA is high. If WAVE = 0, this means that TIOA pin is high. If WAVE = 1, this means that TIOA is driven high. • MTIOB: TIOB Mirror 0 = TIOB is low. If WAVE = 0, this means that TIOB pin is low. If WAVE = 1, this means that TIOB is driven low. 1 = TIOB is high. If WAVE = 0, this means that TIOB pin is high. If WAVE = 1, this means that TIOB is driven high. 585 6384D–ATARM–04-May-09 34.6.11 TC Interrupt Enable Register Register Name:TC_IERx [x=0..2] Access Type:Write-only 31 – 23 – 15 – 7 ETRGS 30 – 22 – 14 – 6 LDRBS 29 – 21 – 13 – 5 LDRAS 28 – 20 – 12 – 4 CPCS 27 – 19 – 11 – 3 CPBS 26 – 18 – 10 – 2 CPAS 25 – 17 – 9 – 1 LOVRS 24 – 16 – 8 – 0 COVFS • COVFS: Counter Overflow 0 = No effect. 1 = Enables the Counter Overflow Interrupt. • LOVRS: Load Overrun 0 = No effect. 1 = Enables the Load Overrun Interrupt. • CPAS: RA Compare 0 = No effect. 1 = Enables the RA Compare Interrupt. • CPBS: RB Compare 0 = No effect. 1 = Enables the RB Compare Interrupt. • CPCS: RC Compare 0 = No effect. 1 = Enables the RC Compare Interrupt. • LDRAS: RA Loading 0 = No effect. 1 = Enables the RA Load Interrupt. • LDRBS: RB Loading 0 = No effect. 1 = Enables the RB Load Interrupt. • ETRGS: External Trigger 0 = No effect. 1 = Enables the External Trigger Interrupt. 586 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 34.6.12 TC Interrupt Disable Register Register Name:TC_IDRx [x=0..2] Access Type:Write-only 31 – 23 – 15 – 7 ETRGS 30 – 22 – 14 – 6 LDRBS 29 – 21 – 13 – 5 LDRAS 28 – 20 – 12 – 4 CPCS 27 – 19 – 11 – 3 CPBS 26 – 18 – 10 – 2 CPAS 25 – 17 – 9 – 1 LOVRS 24 – 16 – 8 – 0 COVFS • COVFS: Counter Overflow 0 = No effect. 1 = Disables the Counter Overflow Interrupt. • LOVRS: Load Overrun 0 = No effect. 1 = Disables the Load Overrun Interrupt (if WAVE = 0). • CPAS: RA Compare 0 = No effect. 1 = Disables the RA Compare Interrupt (if WAVE = 1). • CPBS: RB Compare 0 = No effect. 1 = Disables the RB Compare Interrupt (if WAVE = 1). • CPCS: RC Compare 0 = No effect. 1 = Disables the RC Compare Interrupt. • LDRAS: RA Loading 0 = No effect. 1 = Disables the RA Load Interrupt (if WAVE = 0). • LDRBS: RB Loading 0 = No effect. 1 = Disables the RB Load Interrupt (if WAVE = 0). • ETRGS: External Trigger 0 = No effect. 1 = Disables the External Trigger Interrupt. 587 6384D–ATARM–04-May-09 34.6.13 TC Interrupt Mask Register Register Name:TC_IMRx [x=0..2] Access Type:Read-only 31 – 23 – 15 – 7 ETRGS 30 – 22 – 14 – 6 LDRBS 29 – 21 – 13 – 5 LDRAS 28 – 20 – 12 – 4 CPCS 27 – 19 – 11 – 3 CPBS 26 – 18 – 10 – 2 CPAS 25 – 17 – 9 – 1 LOVRS 24 – 16 – 8 – 0 COVFS • COVFS: Counter Overflow 0 = The Counter Overflow Interrupt is disabled. 1 = The Counter Overflow Interrupt is enabled. • LOVRS: Load Overrun 0 = The Load Overrun Interrupt is disabled. 1 = The Load Overrun Interrupt is enabled. • CPAS: RA Compare 0 = The RA Compare Interrupt is disabled. 1 = The RA Compare Interrupt is enabled. • CPBS: RB Compare 0 = The RB Compare Interrupt is disabled. 1 = The RB Compare Interrupt is enabled. • CPCS: RC Compare 0 = The RC Compare Interrupt is disabled. 1 = The RC Compare Interrupt is enabled. • LDRAS: RA Loading 0 = The Load RA Interrupt is disabled. 1 = The Load RA Interrupt is enabled. • LDRBS: RB Loading 0 = The Load RB Interrupt is disabled. 1 = The Load RB Interrupt is enabled. • ETRGS: External Trigger 0 = The External Trigger Interrupt is disabled. 1 = The External Trigger Interrupt is enabled. 588 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 35. MultiMedia Card Interface (MCI) 35.1 Overview The MultiMedia Card Interface (MCI) supports the MultiMedia Card (MMC) Specification V3.11, the SDIO Specification V1.1 and the SD Memory Card Specification V1.0. The MCI includes a command register, response registers, data registers, timeout counters and error detection logic that automatically handle the transmission of commands and, when required, the reception of the associated responses and data with a limited processor overhead. The MCI supports stream, block and multi-block data read and write, and is compatible with the Peripheral DMA Controller (PDC) channels, minimizing processor intervention for large buffer transfers. The MCI operates at a rate of up to Master Clock divided by 2 and supports the interfacing of 2 slot(s). Each slot may be used to interface with a MultiMediaCard bus (up to 30 Cards) or with a SD Memory Card. Only one slot can be selected at a time (slots are multiplexed). A bit field in the SD Card Register performs this selection. The SD Memory Card communication is based on a 9-pin interface (clock, command, four data and three power lines) and the MultiMedia Card on a 7-pin interface (clock, command, one data, three power lines and one reserved for future use). The SD Memory Card interface also supports MultiMedia Card operations. The main differences between SD and MultiMedia Cards are the initialization process and the bus topology. 589 6384D–ATARM–04-May-09 35.2 Block Diagram Figure 35-1. Block Diagram APB Bridge PDC APB MCCK(1) MCCDA(1) MCDA0(1) PMC MCK MCDA1(1) MCDA2(1) MCDA3(1) MCI Interface PIO MCCDB(1) MCDB0(1) MCDB1(1) MCDB2(1) Interrupt Control MCDB3(1) MCI Interrupt Note: When several MCI (x MCI) are embedded in a product, MCCK refers to MCIx_CK, MCCDA to MCIx_CDA, MCCDB to MCIx_CDB,MCDAy to MCIx_DAy, MCDBy to MCIx_DBy. 590 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 35.3 Application Block Diagram Figure 35-2. Application Block Diagram Application Layer ex: File System, Audio, Security, etc. Physical Layer MCI Interface 1 2 3 4 5 6 78 1234567 MMC 9 SDCard 35.4 Pin Name List I/O Lines Description Pin Description Command/response Clock Data 0..3 of Slot A Data 0..3 of Slot B Type(1) I/O/PP/OD I/O I/O/PP I/O/PP Comments CMD of an MMC or SDCard/SDIO CLK of an MMC or SD Card/SDIO DAT0 of an MMC DAT[0..3] of an SD Card/SDIO DAT0 of an MMC DAT[0..3] of an SD Card/SDIO Table 35-1. Pin Name(2) MCCDA/MCCDB MCCK MCDA0 - MCDA3 MCDB0 - MCDB3 Notes: 1. I: Input, O: Output, PP: Push/Pull, OD: Open Drain. 2. When several MCI (x MCI) are embedded in a product, MCCK refers to MCIx_CK, MCCDA to MCIx_CDA, MCCDB to MCIx_CDB, MCDAy to MCIx_DAy, MCDBy to MCIx_DBy. 35.5 35.5.1 Product Dependencies I/O Lines The pins used for interfacing the MultiMedia Cards or SD Cards may be multiplexed with PIO lines. The programmer must first program the PIO controllers to assign the peripheral functions to MCI pins. 35.5.2 Power Management The MCI may be clocked through the Power Management Controller (PMC), so the programmer must first configure the PMC to enable the MCI clock. 591 6384D–ATARM–04-May-09 35.5.3 Interrupt The MCI interface has an interrupt line connected to the Advanced Interrupt Controller (AIC). Handling the MCI interrupt requires programming the AIC before configuring the MCI. 35.6 Bus Topology Figure 35-3. Multimedia Memory Card Bus Topology 1234567 MMC The MultiMedia Card communication is based on a 7-pin serial bus interface. It has three communication lines and four supply lines. Table 35-2. Pin Number 1 2 3 4 5 6 7 Notes: Bus Topology Name RSV CMD VSS1 VDD CLK VSS2 DAT[0] Type NC I/O/PP/OD S S I/O S I/O/PP (1) Description Not connected Command/response Supply voltage ground Supply voltage Clock Supply voltage ground Data 0 MCI Pin Name(2) (Slot z) MCCDz VSS VDD MCCK VSS MCDz0 1. I: Input, O: Output, PP: Push/Pull, OD: Open Drain. 2. When several MCI (x MCI) are embedded in a product, MCCK refers to MCIx_CK, MCCDA to MCIx_CDA, MCCDB to MCIx_CDB, MCDAy to MCIx_DAy, MCDBy to MCIx_DBy. Figure 35-4. MMC Bus Connections (One Slot) MCI MCDA0 MCCDA MCCK 1234567 MMC1 1234567 MMC2 1234567 MMC3 Note: When several MCI (x MCI) are embedded in a product, MCCK refers to MCIx_CK, MCCDA to MCIx_CDA MCDAy to MCIx_DAy. 592 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Figure 35-5. SD Memory Card Bus Topology 1 2 3 4 5 6 78 9 SD CARD The SD Memory Card bus includes the signals listed in Table 35-3. Table 35-3. Pin Number 1 2 3 4 5 6 7 8 9 Notes: SD Memory Card Bus Signals Name CD/DAT[3] CMD VSS1 VDD CLK VSS2 DAT[0] DAT[1] DAT[2] Type(1) I/O/PP PP S S I/O S I/O/PP I/O/PP I/O/PP Description Card detect/ Data line Bit 3 Command/response Supply voltage ground Supply voltage Clock Supply voltage ground Data line Bit 0 Data line Bit 1 or Interrupt Data line Bit 2 MCI Pin Name(2) (Slot z) MCDz3 MCCDz VSS VDD MCCK VSS MCDz0 MCDz1 MCDz2 1. I: input, O: output, PP: Push Pull, OD: Open Drain. 2. When several MCI (x MCI) are embedded in a product, MCCK refers to MCIx_CK, MCCDA to MCIx_CDA, MCCDB to MCIx_CDB, MCDAy to MCIx_DAy, MCDBy to MCIx_DBy. Figure 35-6. SD Card Bus Connections with One Slot MCDA0 - MCDA3 MCCK MCCDA 1 2 3 4 5 6 78 SD CARD Note: When several MCI (x MCI) are embedded in a product, MCCK refers to MCIx_CK, MCCDA to MCIx_CDA MCDAy to MCIx_DAy. 9 593 6384D–ATARM–04-May-09 Figure 35-7. SD Card Bus Connections with Two Slots MCDA0 - MCDA3 MCCK MCCDA 1 2 3 4 5 6 78 1 2 3 4 5 6 78 1234567 MMC1 1 2 3 4 5 6 78 SD CARD 1 MCDB0 - MCDB3 MCCDB Note: When several MCI (x MCI) are embedded in a product, MCCK refers to MCIx_CK,MCCDA to MCIx_CDA, MCDAy to MCIx_DAy, MCCDB to MCIx_CDB, MCDBy to MCIx_DBy. Figure 35-8. Mixing MultiMedia and SD Memory Cards with Two Slots MCDA0 MCCDA MCCK 1234567 MMC2 9 9 SD CARD 2 1234567 MMC3 MCDB0 - MCDB3 SD CARD MCCDB Note: When several MCI (x MCI) are embedded in a product, MCCK refers to MCIx_CK, MCCDA to MCIx_CDA, MCDAy to MCIx_DAy, MCCDB to MCIx_CDB, MCDBy to MCIx_DBy. When the MCI is configured to operate with SD memory cards, the width of the data bus can be selected in the MCI_SDCR register. Clearing the SDCBUS bit in this register means that the width is one bit; setting it means that the width is four bits. In the case of multimedia cards, only the data line 0 is used. The other data lines can be used as independent PIOs. 594 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 9 AT91SAM9G20 Preliminary 35.7 MultiMedia Card Operations After a power-on reset, the cards are initialized by a special message-based MultiMedia Card bus protocol. Each message is represented by one of the following tokens: • Command: A command is a token that starts an operation. A command is sent from the host either to a single card (addressed command) or to all connected cards (broadcast command). A command is transferred serially on the CMD line. • Response: A response is a token which is sent from an addressed card or (synchronously) from all connected cards to the host as an answer to a previously received command. A response is transferred serially on the CMD line. • Data: Data can be transferred from the card to the host or vice versa. Data is transferred via the data line. Card addressing is implemented using a session address assigned during the initialization phase by the bus controller to all currently connected cards. Their unique CID number identifies individual cards. The structure of commands, responses and data blocks is described in the MultiMedia-Card System Specification. See also Table 35-5 on page 596. MultiMediaCard bus data transfers are composed of these tokens. There are different types of operations. Addressed operations always contain a command and a response token. In addition, some operations have a data token; the others transfer their information directly within the command or response structure. In this case, no data token is present in an operation. The bits on the DAT and the CMD lines are transferred synchronous to the clock MCI Clock. Two types of data transfer commands are defined: • Sequential commands: These commands initiate a continuous data stream. They are terminated only when a stop command follows on the CMD line. This mode reduces the command overhead to an absolute minimum. • Block-oriented commands: These commands send a data block succeeded by CRC bits. Both read and write operations allow either single or multiple block transmission. A multiple block transmission is terminated when a stop command follows on the CMD line similarly to the sequential read or when a multiple block transmission has a pre-defined block count (See “Data Transfer Operation” on page 597.). The MCI provides a set of registers to perform the entire range of MultiMedia Card operations. 35.7.1 Command - Response Operation After reset, the MCI is disabled and becomes valid after setting the MCIEN bit in the MCI_CR Control Register. The PWSEN bit saves power by dividing the MCI clock by 2PWSDIV + 1 when the bus is inactive. The two bits, RDPROOF and WRPROOF in the MCI Mode Register (MCI_MR) allow stopping the MCI Clock during read or write access if the internal FIFO is full. This will guarantee data integrity, not bandwidth. The command and the response of the card are clocked out with the rising edge of the MCI Clock. All the timings for MultiMedia Card are defined in the MultiMediaCard System Specification. 595 6384D–ATARM–04-May-09 The two bus modes (open drain and push/pull) needed to process all the operations are defined in the MCI command register. The MCI_CMDR allows a command to be carried out. For example, to perform an ALL_SEND_CID command: Table 35-4. Host Command CMD S T Content CRC E Z NID Cycles ****** Z S T CID Content Z Z Z The command ALL_SEND_CID and the fields and values for the MCI_CMDR Control Register are described in Table 35-5 and Table 35-6. Table 35-5. CMD Index CMD2 ALL_SEND_CID Command Description Type bcr Argument [31:0] stuff bits Resp R2 Abbreviation ALL_SEND_CID Command Description Asks all cards to send their CID numbers on the CMD line Note: bcr means broadcast command with response. Table 35-6. Field Fields and Values for MCI_CMDR Command Register Value 2 (CMD2) 2 (R2: 136 bits response) 0 (not a special command) 1 0 (NID cycles ==> 5 cycles) 0 (No transfer) X (available only in transfer command) X (available only in transfer command) 0 (not a special command) CMDNB (command number) RSPTYP (response type) SPCMD (special command) OPCMD (open drain command) MAXLAT (max latency for command to response) TRCMD (transfer command) TRDIR (transfer direction) TRTYP (transfer type) IOSPCMD (SDIO special command) The MCI_ARGR contains the argument field of the command. To send a command, the user must perform the following steps: • Fill the argument register (MCI_ARGR) with the command argument. • Set the command register (MCI_CMDR) (see Table 35-6). The command is sent immediately after writing the command register. The status bit CMDRDY in the status register (MCI_SR) is asserted when the command is completed. If the command requires a response, it can be read in the MCI response register (MCI_RSPR). The response size can be from 48 bits up to 136 bits depending on the command. The MCI embeds an error detection to prevent any corrupted data during the transfer. The following flowchart shows how to send a command to the card and read the response if needed. In this example, the status register bits are polled but setting the appropriate bits in the interrupt enable register (MCI_IER) allows using an interrupt method. 596 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Figure 35-9. Command/Response Functional Flow Diagram Set the command argument MCI_ARGR = Argument(1) Set the command MCI_CMDR = Command Read MCI_SR Wait for command ready status flag 0 CMDRDY 1 Check error bits in the status register (1) Yes Status error flags? Read response if required RETURN ERROR(1) RETURN OK Note: 1. If the command is SEND_OP_COND, the CRC error flag is always present (refer to R3 response in the MultiMedia Card specification). 35.7.2 Data Transfer Operation The MultiMedia Card allows several read/write operations (single block, multiple blocks, stream, etc.). These kind of transfers can be selected setting the Transfer Type (TRTYP) field in the MCI Command Register (MCI_CMDR). These operations can be done using the features of the Peripheral DMA Controller (PDC). If the PDCMODE bit is set in MCI_MR, then all reads and writes use the PDC facilities. In all cases, the block length (BLKLEN field) must be defined either in the mode register MCI_MR, or in the Block Register MCI_BLKR. This field determines the size of the data block. Enabling PDC Force Byte Transfer (PDCFBYTE bit in the MCI_MR) allows the PDC to manage with internal byte transfers, so that transfer of blocks with a size different from modulo 4 can be supported. When PDC Force Byte Transfer is disabled, the PDC type of transfers are in words, otherwise the type of transfers are in bytes. 597 6384D–ATARM–04-May-09 Consequent to MMC Specification 3.1, two types of multiple block read (or write) transactions are defined (the host can use either one at any time): • Open-ended/Infinite Multiple block read (or write): The number of blocks for the read (or write) multiple block operation is not defined. The card will continuously transfer (or program) data blocks until a stop transmission command is received. • Multiple block read (or write) with pre-defined block count (since version 3.1 and higher): The card will transfer (or program) the requested number of data blocks and terminate the transaction. The stop command is not required at the end of this type of multiple block read (or write), unless terminated with an error. In order to start a multiple block read (or write) with pre-defined block count, the host must correctly program the MCI Block Register (MCI_BLKR). Otherwise the card will start an open-ended multiple block read. The BCNT field of the Block Register defines the number of blocks to transfer (from 1 to 65535 blocks). Programming the value 0 in the BCNT field corresponds to an infinite block transfer. 35.7.3 Read Operation The following flowchart shows how to read a single block with or without use of PDC facilities. In this example (see Figure 35-10), a polling method is used to wait for the end of read. Similarly, the user can configure the interrupt enable register (MCI_IER) to trigger an interrupt at the end of read. 598 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Figure 35-10. Read Functional Flow Diagram Send SELECT/DESELECT_CARD command(1) to select the card (1) Send SET_BLOCKLEN command No Read with PDC Yes Reset the PDCMODE bit MCI_MR &= ~PDCMODE Set the block length (in bytes) MCI_MR |= (BlockLenght UDP_CSR[endpoint] &= ~(flags); \ while ( (pInterface->UDP_CSR[endpoint] & (flags)) == (flags) ); \ } //! Set flags of UDP UDP_CSR register and waits for synchronization #define Udp_ep_set_flag(pInterface, endpoint, flags) { \ pInterface->UDP_CSR[endpoint] |= (flags); \ while ( (pInterface->UDP_CSR[endpoint] & (flags)) != (flags) ); \ } Note: In a preemptive environment, set or clear the flag and wait for a time of 1 UDPCK clock cycle and 1peripheral clock cycle. However, RX_DATA_BLK0, TXPKTRDY, RX_DATA_BK1 require wait times of 3 UDPCK clock cycles and 3 peripheral clock cycles before accessing DPR. • TXCOMP: Generates an IN Packet with Data Previously Written in the DPR This flag generates an interrupt while it is set to one. Write (Cleared by the firmware): 0 = Clear the flag, clear the interrupt. 1 = No effect. Read (Set by the USB peripheral): 0 = Data IN transaction has not been acknowledged by the Host. 1 = Data IN transaction is achieved, acknowledged by the Host. After having issued a Data IN transaction setting TXPKTRDY, the device firmware waits for TXCOMP to be sure that the host has acknowledged the transaction. 702 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary • RX_DATA_BK0: Receive Data Bank 0 This flag generates an interrupt while it is set to one. Write (Cleared by the firmware): 0 = Notify USB peripheral device that data have been read in the FIFO's Bank 0. 1 = To leave the read value unchanged. Read (Set by the USB peripheral): 0 = No data packet has been received in the FIFO's Bank 0. 1 = A data packet has been received, it has been stored in the FIFO's Bank 0. When the device firmware has polled this bit or has been interrupted by this signal, it must transfer data from the FIFO to the microcontroller memory. The number of bytes received is available in RXBYTCENT field. Bank 0 FIFO values are read through the UDP_FDRx register. Once a transfer is done, the device firmware must release Bank 0 to the USB peripheral device by clearing RX_DATA_BK0. After setting or clearing this bit, a wait time of 3 UDPCK clock cycles and 3 peripheral clock cycles is required before accessing DPR. • RXSETUP: Received Setup This flag generates an interrupt while it is set to one. Read: 0 = No setup packet available. 1 = A setup data packet has been sent by the host and is available in the FIFO. Write: 0 = Device firmware notifies the USB peripheral device that it has read the setup data in the FIFO. 1 = No effect. This flag is used to notify the USB device firmware that a valid Setup data packet has been sent by the host and successfully received by the USB device. The USB device firmware may transfer Setup data from the FIFO by reading the UDP_FDRx register to the microcontroller memory. Once a transfer has been done, RXSETUP must be cleared by the device firmware. Ensuing Data OUT transaction is not accepted while RXSETUP is set. • STALLSENT: Stall Sent (Control, Bulk Interrupt Endpoints)/ISOERROR (Isochronous Endpoints) This flag generates an interrupt while it is set to one. STALLSENT: This ends a STALL handshake. Read: 0 = The host has not acknowledged a STALL. 1 = Host has acknowledged the stall. Write: 0 = Resets the STALLSENT flag, clears the interrupt. 1 = No effect. 703 6384D–ATARM–04-May-09 This is mandatory for the device firmware to clear this flag. Otherwise the interrupt remains. Refer to chapters 8.4.5 and 9.4.5 of the Universal Serial Bus Specification, Rev. 2.0 for more information on the STALL handshake. ISOERROR: A CRC error has been detected in an isochronous transfer. Read: 0 = No error in the previous isochronous transfer. 1 = CRC error has been detected, data available in the FIFO are corrupted. Write: 0 = Resets the ISOERROR flag, clears the interrupt. 1 = No effect. • TXPKTRDY: Transmit Packet Ready This flag is cleared by the USB device. This flag is set by the USB device firmware. Read: 0 = There is no data to send. 1 = The data is waiting to be sent upon reception of token IN. Write: 0 = Can be used in the procedure to cancel transmission data. (See, Section 37.5.2.9 “Transmit Data Cancellation” on page 685) 1 = A new data payload has been written in the FIFO by the firmware and is ready to be sent. This flag is used to generate a Data IN transaction (device to host). Device firmware checks that it can write a data payload in the FIFO, checking that TXPKTRDY is cleared. Transfer to the FIFO is done by writing in the UDP_FDRx register. Once the data payload has been transferred to the FIFO, the firmware notifies the USB device setting TXPKTRDY to one. USB bus transactions can start. TXCOMP is set once the data payload has been received by the host. After setting or clearing this bit, a wait time of 3 UDPCK clock cycles and 3 peripheral clock cycles is required before accessing DPR. • FORCESTALL: Force Stall (used by Control, Bulk and Isochronous Endpoints) Read: 0 = Normal state. 1 = Stall state. Write: 0 = Return to normal state. 1 = Send STALL to the host. Refer to chapters 8.4.5 and 9.4.5 of the Universal Serial Bus Specification, Rev. 2.0 for more information on the STALL handshake. Control endpoints: During the data stage and status stage, this bit indicates that the microcontroller cannot complete the request. 704 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Bulk and interrupt endpoints: This bit notifies the host that the endpoint is halted. The host acknowledges the STALL, device firmware is notified by the STALLSENT flag. • RX_DATA_BK1: Receive Data Bank 1 (only used by endpoints with ping-pong attributes) This flag generates an interrupt while it is set to one. Write (Cleared by the firmware): 0 = Notifies USB device that data have been read in the FIFO’s Bank 1. 1 = To leave the read value unchanged. Read (Set by the USB peripheral): 0 = No data packet has been received in the FIFO's Bank 1. 1 = A data packet has been received, it has been stored in FIFO's Bank 1. When the device firmware has polled this bit or has been interrupted by this signal, it must transfer data from the FIFO to microcontroller memory. The number of bytes received is available in RXBYTECNT field. Bank 1 FIFO values are read through UDP_FDRx register. Once a transfer is done, the device firmware must release Bank 1 to the USB device by clearing RX_DATA_BK1. After setting or clearing this bit, a wait time of 3 UDPCK clock cycles and 3 peripheral clock cycles is required before accessing DPR. • DIR: Transfer Direction (only available for control endpoints) Read-write 0 = Allows Data OUT transactions in the control data stage. 1 = Enables Data IN transactions in the control data stage. Refer to Chapter 8.5.3 of the Universal Serial Bus Specification, Rev. 2.0 for more information on the control data stage. This bit must be set before UDP_CSRx/RXSETUP is cleared at the end of the setup stage. According to the request sent in the setup data packet, the data stage is either a device to host (DIR = 1) or host to device (DIR = 0) data transfer. It is not necessary to check this bit to reverse direction for the status stage. • EPTYPE[2:0]: Endpoint Type Read-write 000 001 101 010 110 011 111 Control Isochronous OUT Isochronous IN Bulk OUT Bulk IN Interrupt OUT Interrupt IN 705 6384D–ATARM–04-May-09 • DTGLE: Data Toggle Read-only 0 = Identifies DATA0 packet. 1 = Identifies DATA1 packet. Refer to Chapter 8 of the Universal Serial Bus Specification, Rev. 2.0 for more information on DATA0, DATA1 packet definitions. • EPEDS: Endpoint Enable Disable Read: 0 = Endpoint disabled. 1 = Endpoint enabled. Write: 0 = Disables endpoint. 1 = Enables endpoint. Control endpoints are always enabled. Reading or writing this field has no effect on control endpoints. Note: After reset, all endpoints are configured as control endpoints (zero). • RXBYTECNT[10:0]: Number of Bytes Available in the FIFO Read-only When the host sends a data packet to the device, the USB device stores the data in the FIFO and notifies the microcontroller. The microcontroller can load the data from the FIFO by reading RXBYTECENT bytes in the UDP_FDRx register. 706 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 37.6.11 UDP FIFO Data Register Register Name:UDP_FDRx [x = 0..5] Access Type: Read-write 31 – 23 – 15 – 7 30 – 22 – 14 – 6 29 – 21 – 13 – 5 28 – 20 – 12 – 4 FIFO_DATA 27 – 19 – 11 – 3 26 – 18 – 10 – 2 25 – 17 – 9 – 1 24 – 16 – 8 – 0 • FIFO_DATA[7:0]: FIFO Data Value The microcontroller can push or pop values in the FIFO through this register. RXBYTECNT in the corresponding UDP_CSRx register is the number of bytes to be read from the FIFO (sent by the host). The maximum number of bytes to write is fixed by the Max Packet Size in the Standard Endpoint Descriptor. It can not be more than the physical memory size associated to the endpoint. Refer to the Universal Serial Bus Specification, Rev. 2.0 for more information. 707 6384D–ATARM–04-May-09 37.6.12 UDP Transceiver Control Register Register Name:UDP_TXVC Access Type: Read-write 31 – 23 – 15 – 7 – 30 – 22 – 14 – 6 – 29 – 21 – 13 – 5 – 28 – 20 – 12 – 4 – 27 – 19 – 11 – 3 – 26 – 18 – 10 – 2 – 25 – 17 – 9 PUON 1 – 24 – 16 – 8 TXVDIS 0 – WARNING: The UDP peripheral clock in the Power Management Controller (PMC) must be enabled before any read/write operations to the UDP registers including the UDP_TXVC register. • TXVDIS: Transceiver Disable When UDP is disabled, power consumption can be reduced significantly by disabling the embedded transceiver. This can be done by setting TXVDIS field. To enable the transceiver, TXVDIS must be cleared. • PUON: Pullup On 0: The 1.5KΩ integrated pullup on DP is disconnected. 1: The 1.5 KΩ integrated pullup on DP is connected. NOTE: If the USB pullup is not connected on DP, the user should not write in any UDP register other than the UDP_TXVC register. This is because if DP and DM are floating at 0, or pulled down, then SE0 is received by the device with the consequence of a USB Reset. 708 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 38. USB Host Port (UHP) 38.1 Overview The USB Host Port (UHP) interfaces the USB with the host application. It handles Open HCI protocol (Open Host Controller Interface) as well as USB v2.0 Full-speed and Low-speed protocols. The USB Host Port integrates a root hub and transceivers on downstream ports. It provides several high-speed half-duplex serial communication ports at a baud rate of 12 Mbit/s. Up to 127 USB devices (printer, camera, mouse, keyboard, disk, etc.) and the USB hub can be connected to the USB host in the USB “tiered star” topology. The USB Host Port controller is fully compliant with the Open HCI specification. The USB Host Port User Interface (registers description) can be found in the Open HCI Rev 1.0 Specification available on http://h18000.www1.hp.com/productinfo/development/openhci.html. The standard OHCI USB stack driver can be easily ported to Atmel’s architecture in the same way all existing class drivers run without hardware specialization. This means that all standard class devices are automatically detected and available to the user application. As an example, integrating an HID (Human Interface Device) class driver provides a plug & play feature for all USB keyboards and mouses. 38.2 Block Diagram Figure 38-1. Block Diagram AHB HCI Slave Block OHCI Registers Control List Processor Block ED & TD Regsisters OHCI Root Hub Registers Embedded USB v2.0 Full-speed Transceiver USB transceiver USB transceiver DP DM DP DM Slave Root Hub and Host SIE PORT S/M PORT S/M AHB HCI Master Block Master Data FIFO 64 x 8 uhp_int MCK UHPCK Access to the USB host operational registers is achieved through the AHB bus slave interface. The Open HCI host controller initializes master DMA transfers through the ASB bus master interface as follows: • Fetches endpoint descriptors and transfer descriptors • Access to endpoint data from system memory 709 6384D–ATARM–04-May-09 • Access to the HC communication area • Write status and retire transfer Descriptor Memory access errors (abort, misalignment) lead to an “Unrecoverable Error” indicated by the corresponding flag in the host controller operational registers. The USB root hub is integrated in the USB host. Several USB downstream ports are available. The number of downstream ports can be determined by the software driver reading the root hub’s operational registers. Device connection is automatically detected by the USB host port logic. USB physical transceivers are integrated in the product and driven by the root hub’s ports. Over current protection on ports can be activated by the USB host controller. Atmel’s standard product does not dedicate pads to external over current protection. 38.3 38.3.1 Product Dependencies I/O Lines DPs and DMs are not controlled by any PIO controllers. The embedded USB physical transceivers are controlled by the USB host controller. 38.3.2 Power Management The USB host controller requires a 48 MHz clock. This clock must be generated by a PLL with a correct accuracy of ± 0.25%. Thus the USB device peripheral receives two clocks from the Power Management Controller (PMC): the master clock MCK used to drive the peripheral user interface (MCK domain) and the UHPCLK 48 MHz clock used to interface with the bus USB signals (Recovered 12 MHz domain). 38.3.3 Interrupt The USB host interface has an interrupt line connected to the Advanced Interrupt Controller (AIC). Handling USB host interrupts requires programming the AIC before configuring the UHP. 38.4 Functional Description Please refer to the Open Host Controller Interface Specification for USB Release 1.0.a. 38.4.1 Host Controller Interface There are two communication channels between the Host Controller and the Host Controller Driver. The first channel uses a set of operational registers located on the USB Host Controller. The Host Controller is the target for all communications on this channel. The operational registers contain control, status and list pointer registers. They are mapped in the memory mapped area. Within the operational register set there is a pointer to a location in the processor address space named the Host Controller Communication Area (HCCA). The HCCA is the second communication channel. The host controller is the master for all communication on this channel. The HCCA contains the head pointers to the interrupt Endpoint Descriptor lists, the head pointer to the done queue and status information associated with start-of-frame processing. The basic building blocks for communication across the interface are Endpoint Descriptors (ED, 4 double words) and Transfer Descriptors (TD, 4 or 8 double words). The host controller assigns 710 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary an Endpoint Descriptor to each endpoint in the system. A queue of Transfer Descriptors is linked to the Endpoint Descriptor for the specific endpoint. Figure 38-2. USB Host Communication Channels Device Enumeration Open HCI Operational Registers Mode HCCA Status Event Frame Int Ratio Control Bulk Host Controller Communications Area Interrupt 0 Interrupt 1 Interrupt 2 ... Interrupt 31 ... ... Done Device Register in Memory Space Shared RAM = Transfer Descriptor = Endpoint Descriptor 38.4.2 Host Controller Driver Figure 38-3. USB Host Drivers User Application User Space Kernel Drivers Mini Driver Class Driver Class Driver HUB Driver USB Driver Host Controller Driver Hardware Host Controller Hardware USB Handling is done through several layers as follows: 711 6384D–ATARM–04-May-09 • Host controller hardware and serial engine: Transmits and receives USB data on the bus. • Host controller driver: Drives the Host controller hardware and handles the USB protocol. • USB Bus driver and hub driver: Handles USB commands and enumeration. Offers a hardware independent interface. • Mini driver: Handles device specific commands. • Class driver: Handles standard devices. This acts as a generic driver for a class of devices, for example the HID driver. 38.5 Typical Connection Figure 38-4. Board Schematic to Interface UHP Device Controller 5V 0.20A Type A Connector 10μF HDMA or HDMB HDPA or HDPB REXT 100nF 10nF REXT A termination serial resistor must be connected to HDP and HDM. The resistor value is defined in the electrical specification of the product (REXT). 712 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 39. Image Sensor Interface (ISI) 39.1 Overview The Image Sensor Interface (ISI) connects a CMOS-type image sensor to the processor and provides image capture in various formats. It does data conversion, if necessary, before the storage in memory through DMA. The ISI supports color CMOS image sensor and grayscale image sensors with a reduced set of functionalities. In grayscale mode, the data stream is stored in memory without any processing and so is not compatible with the LCD controller. Internal FIFOs on the preview and codec paths are used to store the incoming data. The RGB output on the preview path is compatible with the LCD controller. This module outputs the data in RGB format (LCD compatible) and has scaling capabilities to make it compliant to the LCD display resolution (See Table 39-3 on page 716). Several input formats such as preprocessed RGB or YCbCr are supported through the data bus interface. It supports two modes of synchronization: 1. The hardware with ISI_VSYNC and ISI_HSYNC signals 2. The International Telecommunication Union Recommendation ITU-R BT.656-4 Start-ofActive-Video (SAV) and End-of-Active-Video (EAV) synchronization sequence. Using EAV/SAV for synchronization reduces the pin count (ISI_VSYNC, ISI_HSYNC not used). The polarity of the synchronization pulse is programmable to comply with the sensor signals. Table 39-1. Signal ISI_VSYNC ISI_HSYNC ISI_DATA[11..0] ISI_MCK ISI_PCK I/O Description Dir IN IN IN OUT IN Description Vertical Synchronization Horizontal Synchronization Sensor Pixel Data Master Clock Provided to the Image Sensor Pixel Clock Provided by the Image Sensor Figure 39-1. ISI Connection Example Image Sensor Image Sensor Interface data[11..0] CLK PCLK VSYNC HSYNC ISI_DATA[11..0] ISI_MCK ISI_PCK ISI_VSYNC ISI_HSYNC 713 6384D–ATARM–04-May-09 39.2 Block Diagram Figure 39-2. Image Sensor Interface Block Diagram APB bus AHB bus Hsync/Len Vsync/Fen Timing Signals Interface Camera Interrupt Controller From Rx buffers Config Registers Camera Interrupt Request Line APB Interface CCIR-656 Embedded Timing Decoder(SAV/EAV) CMOS sensor Pixel input up to 12 bit YCbCr 4:2:2 8:8:8 RGB 5:6:5 APB Clock Domain AHB Clock Domain Camera AHB Master Interface Scatter Mode Support Pixel Clock Domain Frame Rate Clipping + Color Conversion YCC to RGB 2-D Image Scaler Pixel Formatter Pixel Sampling Module Rx Direct Display FIFO Core Video Arbiter CMOS sensor pixel clock input Clipping + Color Conversion RGB to YCC Packed Formatter Rx Direct Capture FIFO codec_on 39.3 Functional Description The Image Sensor Interface (ISI) supports direct connection to the ITU-R BT. 601/656 8-bit mode compliant sensors and up to 12-bit grayscale sensors. It receives the image data stream from the image sensor on the 12-bit data bus. This module receives up to 12 bits for data, the horizontal and vertical synchronizations and the pixel clock. The reduced pin count alternative for synchronization is supported for sensors that embed SAV (start of active video) and EAV (end of active video) delimiters in the data stream. The Image Sensor Interface interrupt line is generally connected to the Advanced Interrupt Controller and can trigger an interrupt at the beginning of each frame and at the end of a DMA frame transfer. If the SAV/EAV synchronization is used, an interrupt can be triggered on each delimiter event. For 8-bit color sensors, the data stream received can be in several possible formats: YCbCr 4:2:2, RGB 8:8:8, RGB 5:6:5 and may be processed before the storage in memory. The data stream may be sent on both preview path and codec path if the bit CODEC_ON in the ISI_CR1 is one. To optimize the bandwidth, the codec path should be enabled only when a capture is required. In grayscale mode, the input data stream is stored in memory without any processing. The 12-bit data, which represent the grayscale level for the pixel, is stored in memory one or two pixels per word, depending on the GS_MODE bit in the ISI_CR2 register. The codec datapath is not available when grayscale image is selected. A frame rate counter allows users to capture all frames or 1 out of every 2 to 8 frames. 714 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 39.3.1 Data Timing The two data timings using horizontal and vertical synchronization and EAV/SAV sequence synchronization are shown in Figure 39-3 and Figure 39-4. In the VSYNC/HSYNC synchronization, the valid data is captured with the active edge of the pixel clock (ISI_PCK), after SFD lines of vertical blanking and SLD pixel clock periods delay programmed in the control register. The ITU-RBT.656-4 defines the functional timing for an 8-bit wide interface. There are two timing reference signals, one at the beginning of each video data block SAV (0xFF000080) and one at the end of each video data block EAV(0xFF00009D). Only data sent between EAV and SAV is captured. Horizontal blanking and vertical blanking are ignored. Use of the SAV and EAV synchronization eliminates the ISI_VSYNC and ISI_HSYNC signals from the interface, thereby reducing the pin count. In order to retrieve both frame and line synchronization properly, at least one line of vertical blanking is mandatory. Figure 39-3. HSYNC and VSYNC Synchronization Frame ISI_VSYNC 1 line ISI_HSYNC ISI_PCK DATA[7..0] Y Cb Y Cr Y Cb Y Cr Y Cb Y Cr Figure 39-4. SAV and EAV Sequence Synchronization ISII_PCK DATA[7..0] FF 00 00 SAV 80 Y Cb Y Cr Y Cb Y Cr Active Video Y Y Cr Y Cb FF 00 00 EAV 9D 715 6384D–ATARM–04-May-09 39.3.2 Data Ordering The RGB color space format is required for viewing images on a display screen preview, and the YCbCr color space format is required for encoding. All the sensors do not output the YCbCr or RGB components in the same order. The ISI allows the user to program the same component order as the sensor, reducing software treatments to restore the right format. Table 39-2. Mode Default Mode1 Mode2 Mode3 Data Ordering in YCbCr Mode Byte 0 Cb(i) Cr(i) Y(i) Y(i) Byte 1 Y(i) Y(i) Cb(i) Cr(i) Byte 2 Cr(i) Cb(i) Y(i+1) Y(i+1) Byte 3 Y(i+1) Y(i+1) Cr(i) Cb(i) Table 39-3. Mode RGB Format in Default Mode, RGB_CFG = 00, No Swap Byte Byte 0 Byte 1 D7 R7(i) G7(i) B7(i) R7(i+1) R4(i) G2(i) R4(i+1) G2(i+1) D6 R6(i) G6(i) B6(i) R6(i+1) R3(i) G1(i) R3(i+1) G1(i+1) D5 R5(i) G5(i) B5(i) R5(i+1) R2(i) G0(i) R2(i+1) G0(i+1) D4 R4(i) G4(i) B4(i) R4(i+1) R1(i) B4(i) R1(i+1) B4(i+1) D3 R3(i) G3(i) B3(i) R3(i+1) R0(i) B3(i) R0(i+1) B3(i+1) D2 R2(i) G2(i) B2(i) R2(i+1) G5(i) B2(i) G5(i+1) B2(i+1) D1 R1(i) G1(i) B1(i) R1(i+1) G4(i) B1(i) G4(i+1) B1(i+1) D0 R0(i) G0(i) B0(i) R0(i+1) G3(i) B0(i) G3(i+1) B0(i+1) RGB 8:8:8 Byte 2 Byte 3 Byte 0 Byte 1 RGB 5:6:5 Byte 2 Byte 3 Table 39-4. Mode RGB Format, RGB_CFG = 10 (Mode 2), No Swap Byte Byte 0 Byte 1 D7 G2(i) B4(i) G2(i+1) B4(i+1) D6 G1(i) B3(i) G1(i+1) B3(i+1) D5 G0(i) B2(i) G0(i+1) B2(i+1) D4 R4(i) B1(i) R4(i+1) B1(i+1) D3 R3(i) B0(i) R3(i+1) B0(i+1) D2 R2(i) G5(i) R2(i+1) G5(i+1) D1 R1(i) G4(i) R1(i+1) G4(i+1) D0 R0(i) G3(i) R0(i+1) G3(i+1) RGB 5:6:5 Byte 2 Byte 3 716 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Table 39-5. Mode RGB Format in Default Mode, RGB_CFG = 00, Swap Activated Byte Byte 0 Byte 1 D7 R0(i) G0(i) B0(i) R0(i+1) G3(i) B0(i) G3(i+1) B0(i+1) D6 R1(i) G1(i) B1(i) R1(i+1) G4(i) B1(i) G4(i+1) B1(i+1) D5 R2(i) G2(i) B2(i) R2(i+1) G5(i) B2(i) G5(i+1) B2(i+1) D4 R3(i) G3(i) B3(i) R3(i+1) R0(i) B3(i) R0(i+1) B3(i+1) D3 R4(i) G4(i) B4(i) R4(i+1) R1(i) B4(i) R1(i+1) B4(i+1) D2 R5(i) G5(i) B5(i) R5(i+1) R2(i) G0(i) R2(i+1) G0(i+1) D1 R6(i) G6(i) B6(i) R6(i+1) R3(i) G1(i) R3(i+1) G1(i+1) D0 R7(i) G7(i) B7(i) R7(i+1) R4(i) G2(i) R4(i+1) G2(i+1) RGB 8:8:8 Byte 2 Byte 3 Byte 0 Byte 1 RGB 5:6:5 Byte 2 Byte 3 The RGB 5:6:5 input format is processed to be displayed as RGB 5:5:5 format, compliant with the 16-bit mode of the LCD controller. 39.3.3 Clocks The sensor master clock (ISI_MCK) can be generated either by the Advanced Power Management Controller (APMC) through a Programmable Clock output or by an external oscillator connected to the sensor. None of the sensors embeds a power management controller, so providing the clock by the APMC is a simple and efficient way to control power consumption of the system. Care must be taken when programming the system clock. The ISI has two clock domains, the system bus clock and the pixel clock provided by sensor. The two clock domains are not synchronized, but the system clock must be faster than pixel clock. 717 6384D–ATARM–04-May-09 39.3.4 39.3.4.1 Preview Path Scaling, Decimation (Subsampling) This module resizes captured 8-bit color sensor images to fit the LCD display format. The resize module performs only downscaling. The same ratio is applied for both horizontal and vertical resize, then a fractional decimation algorithm is applied. The decimation factor is a multiple of 1/16 and values 0 to 15 are forbidden. Table 39-6. Dec value Dec Factor Decimation Factor 0->15 X 16 1 17 1.063 18 1.125 19 1.188 ... ... 124 7.750 125 7.813 126 7.875 127 7.938 Table 39-7. OUTPUT VGA 640*480 QVGA 320*240 CIF 352*288 QCIF 176*144 Decimation and Scaler Offset Values INPUT 352*288 NA 16 16 16 640*480 16 32 26 53 800*600 20 40 33 66 1280*1024 32 64 56 113 1600*1200 40 80 66 133 2048*1536 51 102 85 170 F F F F Example: Input 1280*1024 Output=640*480 Hratio = 1280/640 =2 Vratio = 1024/480 =2.1333 The decimation factor is 2 so 32/16. 718 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Figure 39-5. Resize Examples 1280 32/16 decimation 640 1024 480 1280 56/16 decimation 352 1024 288 39.3.4.2 Color Space Conversion This module converts YCrCb or YUV pixels to RGB color space. Clipping is performed to ensure that the samples value do not exceed the allowable range. The conversion matrix is defined below and is fully programmable: C0 0 C1 Y – Y off R = C 0 – C 2 – C 3 × C b – C boff G B C0 C4 0 C r – C roff Example of programmable value to convert YCrCb to RGB: ⎧ R = 1,164 ⋅ ( Y – 16 ) + 1,596 ⋅ ( C r – 128 ) ⎪ ⎨ G = 1,164 ⋅ ( Y – 16 ) – 0,813 ⋅ ( C r – 128 ) – 0,392 ⋅ ( C b – 128 ) ⎪ ⎩ B = 1,164 ⋅ ( Y – 16 ) + 2,107 ⋅ ( C b – 128 ) An example of programmable value to convert from YUV to RGB: ⎧ R = Y + 1,596 ⋅ V ⎪ ⎨ G = Y – 0,394 ⋅ U – 0,436 ⋅ V ⎪ B = Y + 2,032 ⋅ U ⎩ 719 6384D–ATARM–04-May-09 39.3.4.3 Memory Interface Preview datapath contains a data formatter that converts 8:8:8 pixel to RGB 5:5:5 format compliant with 16-bit format of the LCD controller. In general, when converting from a color channel with more bits to one with fewer bits, formatter module discards the lower-order bits. Example: Converting from RGB 8:8:8 to RGB 5:6:5, it discards the three LSBs from the red and blue channels, and two LSBs from the green channel. When grayscale mode is enabled, two memory format are supported. One mode supports 2 pixels per word, and the other mode supports 1 pixel per word. Table 39-8. GS_MODE 0 1 Grayscale Memory Mapping Configuration for 12-bit Data DATA[31:24] P_0[11:4] P_0[11:4] DATA[23:16] P_0[3:0], 0000 P_0[3:0], 0000 DATA[15:8] P_1[11:4] 0 DATA[7:0] P_1[3:0], 0000 0 39.3.4.4 FIFO and DMA Features Both preview and Codec datapaths contain FIFOs, asynchronous buffers that are used to safely transfer formatted pixels from Pixel clock domain to AHB clock domain. A video arbiter is used to manage FIFO thresholds and triggers a relevant DMA request through the AHB master interface. Thus, depending on FIFO state, a specified length burst is asserted. Regarding AHB master interface, it supports Scatter DMA mode through linked list operation. This mode of operation improves flexibility of image buffer location and allows the user to allocate two or more frame buffers. The destination frame buffers are defined by a series of Frame Buffer Descriptors (FBD). Each FBD controls the transfer of one entire frame and then optionally loads a further FBD to switch the DMA operation at another frame buffer address. The FBD is defined by a series of two words. The first one defines the current frame buffer address, and the second defines the next FBD memory location. This DMA transfer mode is only available for preview datapath and is configured in the ISI_PPFBD register that indicates the memory location of the first FBD. The primary FBD is programmed into the camera interface controller. The data to be transferred described by an FBD requires several burst access. In the example below, the use of 2 pingpong frame buffers is described. Example The first FBD, stored at address 0x30000, defines the location of the first frame buffer. Destination Address: frame buffer ID0 0x02A000 Next FBD address: 0x30010 Second FBD, stored at address 0x30010, defines the location of the second frame buffer. Destination Address: frame buffer ID1 0x3A000 Transfer width: 32 bit Next FBD address: 0x30000, wrapping to first FBD. Using this technique, several frame buffers can be configured through the linked list. Figure 39-6 illustrates a typical three frame buffer application. Frame n is mapped to frame buffer 0, frame n+1 is mapped to frame buffer 1, frame n+2 is mapped to Frame buffer 2, further frames wrap. A codec request occurs, and the full-size 4:2:2 encoded frame is stored in a dedicated memory space. 720 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary Figure 39-6. Three Frame Buffers Application and Memory Mapping Codec Request Codec Done frame n-1 frame n frame n+1 frame n+2 frame n+3 frame n+4 Memory Space Frame Buffer 3 Frame Buffer 0 LCD Frame Buffer 1 ISI config Space 4:2:2 Image Full ROI 39.3.5 39.3.5.1 Codec Path Color Space Conversion Depending on user selection, this module can be bypassed so that input YCrCb stream is directly connected to the format converter module. If the RGB input stream is selected, this module converts RGB to YCrCb color space with the formulas given below: Y Cr = Cb Y off R C 3 – C 4 – C 5 × G + Cr off B –C6 –C7 C8 Cb off C0 C1 C2 An example of coefficients is given below: ⎧ Y = 0,257 ⋅ R + 0,504 ⋅ G + 0,098 ⋅ B + 16 ⎪ C = 0,439 ⋅ R – 0,368 ⋅ G – 0,071 ⋅ B + 128 ⎨r ⎪ C = – 0,148 ⋅ R – 0,291 ⋅ G + 0,439 ⋅ B + 128 ⎩b 721 6384D–ATARM–04-May-09 39.3.5.2 Memory Interface Dedicated FIFO are used to support packed memory mapping. YCrCb pixel components are sent in a single 32-bit word in a contiguous space (packed). Data is stored in the order of natural scan lines. Planar mode is not supported. DMA Features Unlike preview datapath, codec datapath DMA mode does not support linked list operation. Only the CODEC_DMA_ADDR register is used to configure the frame buffer base address. 39.3.5.3 722 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 39.4 Image Sensor Interface (ISI) User Interface ISI Memory Mapping Register ISI Control 1 Register ISI Control 2 Register ISI Status Register ISI Interrupt Enable Register ISI Interrupt Disable Register ISI Interrupt Mask Register Reserved Reserved ISI Preview Size Register ISI Preview Decimation Factor Register ISI Preview Primary FBD Register ISI Codec DMA Base Address Register ISI CSC YCrCb To RGB Set 0 Register ISI CSC YCrCb To RGB Set 1 Register ISI CSC RGB To YCrCb Set 0 Register ISI CSC RGB To YCrCb Set 1 Register ISI CSC RGB To YCrCb Set 2 Register Reserved Reserved Register ISI_CR1 ISI_CR2 ISI_SR ISI_IER ISI_IDR ISI_IMR ISI_PSIZE ISI_PDECF ISI_PPFBD ISI_CDBA ISI_Y2R_SET0 ISI_Y2R_SET1 ISI_R2Y_SET0 ISI_R2Y_SET1 ISI_R2Y_SET2 – – Access Read-write Read-write Read Read-write Read-write Read-write Read-write Read-write Read-write Read-write Read-write Read-write Read-write Read-write Read-write – – Reset 0x00000002 0x00000000 0x00000000 0x00000000 0x00000000 0x00000000 0x00000000 0x00000010 0x00000000 0x00000000 0x6832cc95 0x00007102 0x01324145 0x01245e38 0x01384a4b – – Table 39-9. Offset 0x00 0x04 0x08 0x0C 0x10 0x14 0x18 0x1C 0x20 0x24 0x28 0x2C 0x30 0x34 0x38 0x3C 0x40 0x44-0xF8 0xFC Note: Several parts of the ISI controller use the pixel clock provided by the image sensor (ISI_PCK). Thus the user must first program the image sensor to provide this clock (ISI_PCK) before programming the Image Sensor Controller. 723 6384D–ATARM–04-May-09 39.4.1 ISI Control 1 Register Register Name: ISI_CR1 Access Type: Read-write Reset Value: 0x00000002 31 30 29 28 SFD 23 22 21 20 SLD 15 CODEC_ON 7 CRC_SYNC 14 THMASK 6 EMB_SYNC 5 13 12 FULL 4 PIXCLK_POL 11 3 VSYNC_POL 10 9 FRATE 1 ISI_DIS 8 19 18 17 16 27 26 25 24 2 HSYNC_POL 0 ISI_RST • ISI_RST: Image Sensor Interface Reset Write-only. Refer to bit SOFTRST in Section 39.4.3 “ISI Status Register” on page 728 for soft reset status. 0: No action 1: Resets the image sensor interface. • ISI_DIS: Image Sensor Disable: 0: Enable the image sensor interface. 1: Finish capturing the current frame and then shut down the module. • HSYNC_POL: Horizontal Synchronization Polarity 0: HSYNC active high 1: HSYNC active low • VSYNC_POL: Vertical sYnchronization Polarity 0: VSYNC active high 1: VSYNC active low • PIXCLK_POL: Pixel Clock Polarity 0: Data is sampled on rising edge of pixel clock 1: Data is sampled on falling edge of pixel clock • EMB_SYNC: Embedded Synchronization 0: Synchronization by HSYNC, VSYNC 1: Synchronization by embedded synchronization sequence SAV/EAV • CRC_SYNC: Embedded Synchronization 0: No CRC correction is performed on embedded synchronization 724 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 1: CRC correction is performed. if the correction is not possible, the current frame is discarded and the CRC_ERR is set in the status register. • FRATE: Frame Rate [0..7] 0: All the frames are captured, else one frame every FRATE+1 is captured. • FULL: Full Mode is Allowed 1: Both codec and preview datapaths are working simultaneously • THMASK: Threshold Mask 0: 4, 8 and 16 AHB bursts are allowed 1: 8 and 16 AHB bursts are allowed 2: Only 16 AHB bursts are allowed • CODEC_ON: Enable the Codec Path Enable Bit Write-only. 0: The codec path is disabled 1: The codec path is enabled and the next frame is captured. Refer to bit CDC_PND in “ISI Status Register” on page 728. • SLD: Start of Line Delay SLD pixel clock periods to wait before the beginning of a line. • SFD: Start of Frame Delay SFD lines are skipped at the beginning of the frame. 725 6384D–ATARM–04-May-09 39.4.2 ISI Control 2 Register Register Name: ISI_CR2 Access Type: Read-write Reset Value: 0x0 31 RGB_CFG 23 22 21 30 29 YCC_SWAP 20 IM_HSIZE 15 COL_SPACE 7 14 RGB_SWAP 6 13 GRAYSCALE 5 12 RGB_MODE 4 IM_VSIZE 11 GS_MODE 3 10 9 IM_VSIZE 1 8 28 27 19 26 25 IM_HSIZE 17 24 18 16 2 0 • IM_VSIZE: Vertical Size of the Image Sensor [0..2047] Vertical size = IM_VSIZE + 1 • GS_MODE 0: 2 pixels per word 1: 1 pixel per word • RGB_MODE: RGB Input Mode 0: RGB 8:8:8 24 bits 1: RGB 5:6:5 16 bits • GRAYSCALE 0: Grayscale mode is disabled 1: Input image is assumed to be grayscale coded • RGB_SWAP 0: D7 -> R7 1: D0 -> R7 The RGB_SWAP has no effect when the grayscale mode is enabled. • COL_SPACE: Color Space for The Image Data 0: YCbCr 1: RGB • IM_HSIZE: Horizontal Size of the Image Sensor [0..2047] Horizontal size = IM_HSIZE + 1 726 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary • YCC_SWAP: Defines the YCC Image Data YCC_SWAP 00: Default 01: Mode1 10: Mode2 11: Mode3 Byte 0 Cb(i) Cr(i) Y(i) Y(i) Byte 1 Y(i) Y(i) Cb(i) Cr(i) Byte 2 Cr(i) Cb(i) Y(i+1) Y(i+1) Byte 3 Y(i+1) Y(i+1) Cr(i) Cb(i) • RGB_CFG: Defines RGB Pattern when RGB_MODE is set to 1 RGB_CFG 00: Default 01: Mode1 10: Mode2 11: Mode3 Byte 0 R/G(MSB) B/G(MSB) G(LSB)/R G(LSB)/B Byte 1 G(LSB)/B G(LSB)/R B/G(MSB) R/G(MSB) Byte 2 R/G(MSB) B/G(MSB) G(LSB)/R G(LSB)/B Byte 3 G(LSB)/B G(LSB)/R B/G(MSB) R/G(MSB) If RGB_MODE is set to RGB 8:8:8, then RGB_CFG = 0 implies RGB color sequence, else it implies BGR color sequence. 727 6384D–ATARM–04-May-09 39.4.3 ISI Status Register Register Name: ISI_SR Access Type: Read Reset Value: 0x0 31 – 23 – 15 – 7 FO_P_EMP 30 – 22 – 14 – 6 FO_P_OVF 29 – 21 – 13 – 5 FO_C_OVF 28 – 20 – 12 – 4 CRC_ERR 27 – 19 – 11 – 3 CDC_PND 26 – 18 – 10 – 2 SOFTRST 25 – 17 – 9 FR_OVR 1 DIS 24 – 16 – 8 FO_C_EMP 0 SOF • SOF: Start of Frame 0: No start of frame has been detected. 1: A start of frame has been detected. • DIS: Image Sensor Interface Disable 0: The image sensor interface is enabled. 1: The image sensor interface is disabled and stops capturing data. The DMA controller and the core can still read the FIFOs. • SOFTRST: Software Reset 0: Software reset not asserted or not completed. 1: Software reset has completed successfully. • CDC_PND: Codec Request Pending 0: No request asserted. 1: A codec request is pending. If a codec request is asserted during a frame, the CDC_PND bit rises until the start of a new frame. The capture is completed when the flag FO_C_EMP = 1. • CRC_ERR: CRC Synchronization Error 0: No CRC error in the embedded synchronization frame (SAV/EAV) 1: The CRC_SYNC is enabled in the control register and an error has been detected and not corrected. The frame is discarded and the ISI waits for a new one. • FO_C_OVF: FIFO Codec Overflow 0: No overflow 1: An overrun condition has occurred in input FIFO on the codec path. The overrun happens when the FIFO is full and an attempt is made to write a new sample to the FIFO. 728 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary • FO_P_OVF: FIFO Preview Overflow 0: No overflow 1: An overrun condition has occurred in input FIFO on the preview path. The overrun happens when the FIFO is full and an attempt is made to write a new sample to the FIFO. • FO_P_EMP 0:The DMA has not finished transferring all the contents of the preview FIFO. 1:The DMA has finished transferring all the contents of the preview FIFO. • FO_C_EMP 0: The DMA has not finished transferring all the contents of the codec FIFO. 1: The DMA has finished transferring all the contents of the codec FIFO. • FR_OVR: Frame Rate Overrun 0: No frame overrun. 1: Frame overrun, the current frame is being skipped because a vsync signal has been detected while flushing FIFOs. 729 6384D–ATARM–04-May-09 39.4.4 Interrupt Enable Register Register Name: ISI_IER Access Type: Read-write Reset Value: 0x0 31 – 23 – 15 – 7 FO_P_EMP 30 – 22 – 14 – 6 FO_P_OVF 29 – 21 – 13 – 5 FO_C_OVF 28 – 20 – 12 – 4 CRC_ERR 27 – 19 – 11 – 3 – 26 – 18 – 10 – 2 SOFTRST 25 – 17 – 9 FR_OVR 1 DIS 24 – 16 – 8 FO_C_EMP 0 SOF • SOF: Start of Frame 1: Enables the Start of Frame interrupt. • DIS: Image Sensor Interface Disable 1: Enables the DIS interrupt. • SOFTRST: Soft Reset 1: Enables the Soft Reset Completion interrupt. • CRC_ERR: CRC Synchronization Error 1: Enables the CRC_SYNC interrupt. • FO_C_OVF: FIFO Codec Overflow 1: Enables the codec FIFO overflow interrupt. • FO_P_OVF: FIFO Preview Overflow 1: Enables the preview FIFO overflow interrupt. • FO_P_EMP 1: Enables the preview FIFO empty interrupt. • FO_C_EMP 1: Enables the codec FIFO empty interrupt. • FR_OVR: Frame Overrun 1: Enables the Frame overrun interrupt. 730 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 39.4.5 ISI Interrupt Disable Register Register Name: ISI_IDR Access Type: Read-write Reset Value: 0x0 31 – 23 – 15 – 7 FO_P_EMP 30 – 22 – 14 – 6 FO_P_OVF 29 – 21 – 13 – 5 FO_C_OVF 28 – 20 – 12 – 4 CRC_ERR 27 – 19 – 11 – 3 – 26 – 18 – 10 – 2 SOFTRST 25 – 17 – 9 FR_OVR 1 DIS 24 – 16 – 8 FO_C_EMP 0 SOF • SOF: Start of Frame 1: Disables the Start of Frame interrupt. • DIS: Image Sensor Interface Disable 1: Disables the DIS interrupt. • SOFTRST 1: Disables the soft reset completion interrupt. • CRC_ERR: CRC Synchronization Error 1: Disables the CRC_SYNC interrupt. • FO_C_OVF: FIFO Codec Overflow 1: Disables the codec FIFO overflow interrupt. • FO_P_OVF: FIFO Preview Overflow 1: Disables the preview FIFO overflow interrupt. • FO_P_EMP 1: Disables the preview FIFO empty interrupt. • FO_C_EMP 1: Disables the codec FIFO empty interrupt. • FR_OVR 1: Disables frame overrun interrupt. 731 6384D–ATARM–04-May-09 39.4.6 ISI Interrupt Mask Register Register Name: ISI_IMR Access Type: Read-write Reset Value: 0x0 31 – 23 – 15 – 7 FO_P_EMP 30 – 22 – 14 – 6 FO_P_OVF 29 – 21 – 13 – 5 FO_C_OVF 28 – 20 – 12 – 4 CRC_ERR 27 – 19 – 11 – 3 – 26 – 18 – 10 – 2 SOFTRST 25 – 17 – 9 FR_OVR 1 DIS 24 – 16 – 8 FO_C_EMP 0 SOF • SOF: Start of Frame 0: The Start of Frame interrupt is disabled. 1: The Start of Frame interrupt is enabled. • DIS: Image Sensor Interface Disable 0: The DIS interrupt is disabled. 1: The DIS interrupt is enabled. • SOFTRST 0: The soft reset completion interrupt is enabled. 1: The soft reset completion interrupt is disabled. • CRC_ERR: CRC Synchronization Error 0: The CRC_SYNC interrupt is disabled. 1: The CRC_SYNC interrupt is enabled. • FO_C_OVF: FIFO Codec Overflow 0: The codec FIFO overflow interrupt is disabled. 1: The codec FIFO overflow interrupt is enabled. • FO_P_OVF: FIFO Preview Overflow 0: The preview FIFO overflow interrupt is disabled. 1: The preview FIFO overflow interrupt is enabled. • FO_P_EMP 0: The preview FIFO empty interrupt is disabled. 1: The preview FIFO empty interrupt is enabled. 732 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary • FO_C_EMP 0: The codec FIFO empty interrupt is disabled. 1: The codec FIFO empty interrupt is enabled. • FR_OVR: Frame Rate Overrun 0: The frame overrun interrupt is disabled. 1: The frame overrun interrupt is enabled. 733 6384D–ATARM–04-May-09 39.4.7 ISI Preview Register Register Name: ISI_PSIZE Access Type: Read-write Reset Value: 0x0 31 – 23 30 – 22 29 – 21 28 – 20 PREV_HSIZE 27 – 19 26 – 18 25 PREV_HSIZE 17 24 16 15 – 7 14 – 6 13 – 5 12 – 4 PREV_VSIZE 11 – 3 10 – 2 9 PREV_VSIZE 1 8 0 • PREV_VSIZE: Vertical Size for the Preview Path Vertical Preview size = PREV_VSIZE + 1 (480 max only in RGB mode). • PREV_HSIZE: Horizontal Size for the Preview Path Horizontal Preview size = PREV_HSIZE + 1 (640 max only in RGB mode). 734 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 39.4.8 ISI Preview Decimation Factor Register Register Name: ISI_PDECF Access Type: Read-write Reset Value: 0x00000010 31 – 23 – 15 – 7 30 – 22 – 14 – 6 29 – 21 – 13 – 5 28 – 20 – 12 – 4 27 – 19 – 11 – 3 26 – 18 – 10 – 2 25 – 17 – 9 – 1 24 – 16 – 8 – 0 DEC_FACTOR • DEC_FACTOR: Decimation Factor DEC_FACTOR is 8-bit width, range is from 16 to 255. Values from 0 to 16 do not perform any decimation. 735 6384D–ATARM–04-May-09 39.4.9 ISI Preview Primary FBD Register Register Name: ISI_PPFBD Access Type: Read-write Reset Value: 0x0 31 30 29 28 27 PREV_FBD_ADDR 20 19 PREV_FBD_ADDR 12 11 PREV_FBD_ADDR 4 3 PREV_FBD_ADDR 26 25 24 23 22 21 18 17 16 15 14 13 10 9 8 7 6 5 2 1 0 • PREV_FBD_ADDR: Base Address for Preview Frame Buffer Descriptor Written with the address of the start of the preview frame buffer queue, reads as a pointer to the current buffer being used. The frame buffer is forced to word alignment. 736 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 39.4.10 ISI Codec DMA Base Address Register Register Name: ISI_CDBA Access Type: Read-write Reset Value: 0x0 31 30 29 28 27 CODEC_DMA_ADDR 20 19 CODEC_DMA_ADDR 12 11 CODEC_DMA_ADDR 4 3 CODEC_DMA_ADDR 26 25 24 23 22 21 18 17 16 15 14 13 10 9 8 7 6 5 2 1 0 • CODEC_DMA_ADDR: Base Address for Codec DMA This register contains codec datapath start address of buffer location. 737 6384D–ATARM–04-May-09 39.4.11 ISI Color Space Conversion YCrCb to RGB Set 0 Register Register Name: ISI_Y2R_SET0 Access Type: Read-write Reset Value: 0x6832cc95 31 30 29 28 C3 27 26 25 24 23 22 21 20 C2 19 18 17 16 15 14 13 12 C1 11 10 9 8 7 6 5 4 C0 3 2 1 0 • C0: Color Space Conversion Matrix Coefficient C0 C0 element, default step is 1/128, ranges from 0 to 1.9921875. • C1: Color Space Conversion Matrix Coefficient C1 C1 element, default step is 1/128, ranges from 0 to 1.9921875. • C2: Color Space Conversion Matrix Coefficient C2 C2 element, default step is 1/128, ranges from 0 to 1.9921875. • C3: Color Space Conversion Matrix Coefficient C3 C3 element default step is 1/128, ranges from 0 to 1.9921875. 738 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 39.4.12 ISI Color Space Conversion YCrCb to RGB Set 1 Register Register Name: ISI_Y2R_SET1 Access Type: Read-write Reset Value: 0x00007102 31 – 23 – 15 – 30 – 22 – 14 Cboff 29 – 21 – 13 Croff 28 – 20 – 12 Yoff 27 – 19 – 11 – 26 – 18 – 10 – 25 – 17 – 9 – 24 – 16 – 8 C4 C4 • C4: Color Space Conversion Matrix Coefficient C4 C4 element default step is 1/128, ranges from 0 to 3.9921875. • Yoff: Color Space Conversion Luminance Default Offset 0: No offset. 1: Offset = 128. • Croff: Color Space Conversion Red Chrominance Default Offset 0: No offset. 1: Offset = 16. • Cboff: Color Space Conversion Blue Chrominance Default Offset 0: No offset. 1: Offset = 16. 739 6384D–ATARM–04-May-09 39.4.13 ISI Color Space Conversion RGB to YCrCb Set 0 Register Register Name: ISI_R2Y_SET0 Access Type: Read-write Reset Value: 0x01324145 31 – 23 30 – 22 29 – 21 28 – 20 C2 27 – 19 26 – 18 25 – 17 24 Roff 16 15 14 13 12 C1 11 10 9 8 7 6 5 4 C0 3 2 1 0 • C0: Color Space Conversion Matrix Coefficient C0 C0 element default step is 1/256, from 0 to 0.49609375. • C1: Color Space Conversion Matrix Coefficient C1 C1 element default step is 1/128, from 0 to 0.9921875. • C2: Color Space Conversion Matrix Coefficient C2 C2 element default step is 1/512, from 0 to 0.2480468875. • Roff: Color Space Conversion Red Component Offset 0: No offset. 1: Offset = 16. 740 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 39.4.14 ISI Color Space Conversion RGB to YCrCb Set 1 Register Register Name: ISI_R2Y_SET1 Access Type: Read-write Reset Value: 0x01245e38 31 – 23 30 – 22 29 – 21 28 – 20 C5 27 – 19 26 – 18 25 – 17 24 Goff 16 15 14 13 12 C4 11 10 9 8 7 6 5 4 C3 3 2 1 0 • C3: Color Space Conversion Matrix Coefficient C3 C0 element default step is 1/128, ranges from 0 to 0.9921875. • C4: Color Space Conversion Matrix Coefficient C4 C1 element default step is 1/256, ranges from 0 to 0.49609375. • C5: Color Space Conversion Matrix Coefficient C5 C1 element default step is 1/512, ranges from 0 to 0.2480468875. • Goff: Color Space Conversion Green Component Offset 0: No offset. 1: Offset = 128. 741 6384D–ATARM–04-May-09 39.4.15 ISI Color Space Conversion RGB to YCrCb Set 2 Register Register Name: ISI_R2Y_SET2 Access Type: Read-write Reset Value: 0x01384a4b 31 – 23 30 – 22 29 – 21 28 – 20 C8 27 – 19 26 – 18 25 – 17 24 Boff 16 15 14 13 12 C7 11 10 9 8 7 6 5 4 C6 3 2 1 0 • C6: Color Space Conversion Matrix Coefficient C6 C6 element default step is 1/512, ranges from 0 to 0.2480468875. • C7: Color Space Conversion Matrix coefficient C7 C7 element default step is 1/256, ranges from 0 to 0.49609375. • C8: Color Space Conversion Matrix Coefficient C8 C8 element default step is 1/128, ranges from 0 to 0.9921875. • Boff: Color Space Conversion Blue Component Offset 0: No offset. 1: Offset = 128. 742 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 40. Analog-to-digital Converter (ADC) 40.1 Overview The ADC is based on a Successive Approximation Register (SAR) 10-bit Analog-to-Digital Converter (ADC). It also integrates a 4-to-1 analog multiplexer, making possible the analog-to-digital conversions of 4 analog lines. The conversions extend from 0V to ADVREF. The ADC supports an 8-bit or 10-bit resolution mode, and conversion results are reported in a common register for all channels, as well as in a channel-dedicated register. Software trigger, external trigger on rising edge of the ADTRG pin or internal triggers from Timer Counter output(s) are configurable. The ADC also integrates a Sleep Mode and a conversion sequencer and connects with a PDC channel. These features reduce both power consumption and processor intervention. Finally, the user can configure ADC timings, such as Startup Time and Sample & Hold Time. 40.2 Block Diagram Figure 40-1. Analog-to-Digital Converter Block Diagram Timer Counter Channels ADC Trigger Selection ADTRG Control Logic ADC Interrupt AIC VDDANA ADVREF ASB ADPDC Dedicated Analog Inputs ADUser Interface ADSuccessive Approximation Register Analog-to-Digital Converter APB Peripheral Bridge AD- Analog Inputs Multiplexed with I/O lines PIO AD- AD- GND 743 6384D–ATARM–04-May-09 40.3 Signal Description ADC Pin Description Description Analog power supply Reference voltage Analog input channels External trigger Table 40-1. Pin Name VDDANA ADVREF AD0 - AD3 ADTRG 40.4 40.4.1 Product Dependencies Power Management The ADC is automatically clocked after the first conversion in Normal Mode. In Sleep Mode, the ADC clock is automatically stopped after each conversion. As the logic is small and the ADC cell can be put into Sleep Mode, the Power Management Controller has no effect on the ADC behavior. Interrupt Sources The ADC interrupt line is connected on one of the internal sources of the Advanced Interrupt Controller. Using the ADC interrupt requires the AIC to be programmed first. Analog Inputs The analog input pins can be multiplexed with PIO lines. In this case, the assignment of the ADC input is automatically done as soon as the corresponding channel is enabled by writing the register ADC_CHER. By default, after reset, the PIO line is configured as input with its pull-up enabled and the ADC input is connected to the GND. 40.4.2 40.4.3 40.4.4 I/O Lines The pin ADTRG may be shared with other peripheral functions through the PIO Controller. In this case, the PIO Controller should be set accordingly to assign the pin ADTRG to the ADC function. 40.4.5 Timer Triggers Timer Counters may or may not be used as hardware triggers depending on user requirements. Thus, some or all of the timer counters may be non-connected. 40.4.6 Conversion Performances For performance and electrical characteristics of the ADC, see the DC Characteristics section. 744 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 40.5 40.5.1 Functional Description Analog-to-digital Conversion The ADC uses the ADC Clock to perform conversions. Converting a single analog value to a 10bit digital data requires Sample and Hold Clock cycles as defined in the field SHTIM of the “ADC Mode Register” on page 752 and 10 ADC Clock cycles. The ADC Clock frequency is selected in the PRESCAL field of the Mode Register (ADC_MR). The ADC clock range is between MCK/2, if PRESCAL is 0, and MCK/128, if PRESCAL is set to 63 (0x3F). PRESCAL must be programmed in order to provide an ADC clock frequency according to the parameters given in the Product definition section. 40.5.2 Conversion Reference The conversion is performed on a full range between 0V and the reference voltage pin ADVREF. Analog inputs between these voltages convert to values based on a linear conversion. Conversion Resolution The ADC supports 8-bit or 10-bit resolutions. The 8-bit selection is performed by setting the bit LOWRES in the ADC Mode Register (ADC_MR). By default, after a reset, the resolution is the highest and the DATA field in the data registers is fully used. By setting the bit LOWRES, the ADC switches in the lowest resolution and the conversion results can be read in the eight lowest significant bits of the data registers. The two highest bits of the DATA field in the corresponding ADC_CDR register and of the LDATA field in the ADC_LCDR register read 0. Moreover, when a PDC channel is connected to the ADC, 10-bit resolution sets the transfer request sizes to 16-bit. Setting the bit LOWRES automatically switches to 8-bit data transfers. In this case, the destination buffers are optimized. 40.5.3 745 6384D–ATARM–04-May-09 40.5.4 Conversion Results When a conversion is completed, the resulting 10-bit digital value is stored in the Channel Data Register (ADC_CDR) of the current channel and in the ADC Last Converted Data Register (ADC_LCDR). The channel EOC bit in the Status Register (ADC_SR) is set and the DRDY is set. In the case of a connected PDC channel, DRDY rising triggers a data transfer request. In any case, either EOC and DRDY can trigger an interrupt. Reading one of the ADC_CDR registers clears the corresponding EOC bit. Reading ADC_LCDR clears the DRDY bit and the EOC bit corresponding to the last converted channel. Figure 40-2. EOCx and DRDY Flag Behavior Write the ADC_CR with START = 1 Read the ADC_CDRx Write the ADC_CR with START = 1 Read the ADC_LCDR CHx (ADC_CHSR) EOCx (ADC_SR) Conversion Time Conversion Time DRDY (ADC_SR) 746 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary If the ADC_CDR is not read before further incoming data is converted, the corresponding Overrun Error (OVRE) flag is set in the Status Register (ADC_SR). In the same way, new data converted when DRDY is high sets the bit GOVRE (General Overrun Error) in ADC_SR. The OVRE and GOVRE flags are automatically cleared when ADC_SR is read. Figure 40-3. GOVRE and OVREx Flag Behavior Read ADC_SR ADTRG CH0 (ADC_CHSR) CH1 (ADC_CHSR) ADC_LCDR ADC_CDR0 ADC_CDR1 Undefined Data Undefined Data Undefined Data Data A Data A Data B Data C Data C Data B EOC0 (ADC_SR) Conversion Conversion Read ADC_CDR0 EOC1 (ADC_SR) Conversion Read ADC_CDR1 GOVRE (ADC_SR) DRDY (ADC_SR) OVRE0 (ADC_SR) Warning: If the corresponding channel is disabled during a conversion or if it is disabled and then reenabled during a conversion, its associated data and its corresponding EOC and OVRE flags in ADC_SR are unpredictable. 747 6384D–ATARM–04-May-09 40.5.5 Conversion Triggers Conversions of the active analog channels are started with a software or a hardware trigger. The software trigger is provided by writing the Control Register (ADC_CR) with the bit START at 1. The hardware trigger can be one of the TIOA outputs of the Timer Counter channels, or the external trigger input of the ADC (ADTRG). The hardware trigger is selected with the field TRGSEL in the Mode Register (ADC_MR). The selected hardware trigger is enabled with the bit TRGEN in the Mode Register (ADC_MR). If a hardware trigger is selected, the start of a conversion is detected at each rising edge of the selected signal. If one of the TIOA outputs is selected, the corresponding Timer Counter channel must be programmed in Waveform Mode. Only one start command is necessary to initiate a conversion sequence on all the channels. The ADC hardware logic automatically performs the conversions on the active channels, then waits for a new request. The Channel Enable (ADC_CHER) and Channel Disable (ADC_CHDR) Registers enable the analog channels to be enabled or disabled independently. If the ADC is used with a PDC, only the transfers of converted data from enabled channels are performed and the resulting data buffers should be interpreted accordingly. Warning: Enabling hardware triggers does not disable the software trigger functionality. Thus, if a hardware trigger is selected, the start of a conversion can be initiated either by the hardware or the software trigger. 40.5.6 Sleep Mode and Conversion Sequencer The ADC Sleep Mode maximizes power saving by automatically deactivating the ADC when it is not being used for conversions. Sleep Mode is selected by setting the bit SLEEP in the Mode Register ADC_MR. The SLEEP mode is automatically managed by a conversion sequencer, which can automatically process the conversions of all channels at lowest power consumption. When a start conversion request occurs, the ADC is automatically activated. As the analog cell requires a start-up time, the logic waits during this time and starts the conversion on the enabled channels. When all conversions are complete, the ADC is deactivated until the next trigger. Triggers occurring during the sequence are not taken into account. The conversion sequencer allows automatic processing with minimum processor intervention and optimized power consumption. Conversion sequences can be performed periodically using a Timer/Counter output. The periodic acquisition of several samples can be processed automatically without any intervention of the processor thanks to the PDC. Note: The reference voltage pins always remain connected in normal mode as in sleep mode. 748 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 40.5.7 ADC Timings Each ADC has its own minimal Startup Time that is programmed through the field STARTUP in the Mode Register ADC_MR. In the same way, a minimal Sample and Hold Time is necessary for the ADC to guarantee the best converted final value between two channels selection. This time has to be programmed through the bitfield SHTIM in the Mode Register ADC_MR. Warning: No input buffer amplifier to isolate the source is included in the ADC. This must be taken into consideration to program a precise value in the SHTIM field. See the section, ADC Characteristics in the product datasheet. 749 6384D–ATARM–04-May-09 40.6 Analog-to-Digital Converter (ADC) User Interface Register Mapping Register Control Register Mode Register Reserved Reserved Channel Enable Register Channel Disable Register Channel Status Register Status Register Last Converted Data Register Interrupt Enable Register Interrupt Disable Register Interrupt Mask Register Channel Data Register 0 Channel Data Register 1 ... Channel Data Register 3 Reserved Name ADC_CR ADC_MR – – ADC_CHER ADC_CHDR ADC_CHSR ADC_SR ADC_LCDR ADC_IER ADC_IDR ADC_IMR ADC_CDR0 ADC_CDR1 ... ADC_CDR3 – Access Write-only Read-write – – Write-only Write-only Read-only Read-only Read-only Write-only Write-only Read-only Read-only Read-only ... Read-only – Reset – 0x00000000 – – – – 0x00000000 0x000C0000 0x00000000 – – 0x00000000 0x00000000 0x00000000 ... 0x00000000 – Table 40-2. Offset 0x00 0x04 0x08 0x0C 0x10 0x14 0x18 0x1C 0x20 0x24 0x28 0x2C 0x30 0x34 ... 0x3C 0x44 - 0xFC 750 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 40.6.1 Name: Access: 31 ADC Control Register ADC_CR Write-only 30 29 28 27 26 25 24 – 23 – 22 – 21 – 20 – 19 – 18 – 17 – 16 – 15 – 14 – 13 – 12 – 11 – 10 – 9 – 8 – 7 – 6 – 5 – 4 – 3 – 2 – 1 – 0 – – – – – – START SWRST • SWRST: Software Reset 0 = No effect. 1 = Resets the ADC simulating a hardware reset. • START: Start Conversion 0 = No effect. 1 = Begins analog-to-digital conversion. 751 6384D–ATARM–04-May-09 40.6.2 Name: Access: 31 ADC Mode Register ADC_MR Read-write 30 29 28 27 26 25 24 – 23 – 22 – 21 – 20 19 18 SHTIM 17 16 – 15 – 14 – 13 12 11 STARTUP 10 9 8 – 7 – 6 5 4 3 PRESCAL 2 1 0 – – SLEEP LOWRES TRGSEL TRGEN • TRGEN: Trigger Enable TRGEN 0 1 Selected TRGEN Hardware triggers are disabled. Starting a conversion is only possible by software. Hardware trigger selected by TRGSEL field is enabled. • TRGSEL: Trigger Selection TRGSEL 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 Selected TRGSEL TIOA Ouput of the Timer Counter Channel 0 TIOA Ouput of the Timer Counter Channel 1 TIOA Ouput of the Timer Counter Channel 2 Reserved Reserved Reserved External trigger Reserved • LOWRES: Resolution LOWRES 0 1 Selected Resolution 10-bit resolution 8-bit resolution • SLEEP: Sleep Mode SLEEP 0 1 Selected Mode Normal Mode Sleep Mode 752 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary • PRESCAL: Prescaler Rate Selection ADCClock = MCK / ( (PRESCAL+1) * 2 ) • STARTUP: Start Up Time Startup Time = (STARTUP+1) * 8 / ADCClock • SHTIM: Sample & Hold Time Sample & Hold Time = (SHTIM+1) / ADCClock 753 6384D–ATARM–04-May-09 40.6.3 Name: Access: 31 ADC Channel Enable Register ADC_CHER Write-only 30 29 28 27 26 25 24 – 23 – 22 – 21 – 20 – 19 – 18 – 17 – 16 – 15 – 14 – 13 – 12 – 11 – 10 – 9 – 8 – 7 – 6 – 5 – 4 – 3 – 2 – 1 – 0 – – – – CH3 CH2 CH1 CH0 • CHx: Channel x Enable 0 = No effect. 1 = Enables the corresponding channel. 754 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 40.6.4 Name: Access: 31 ADC Channel Disable Register ADC_CHDR Write-only 30 29 28 27 26 25 24 – 23 – 22 – 21 – 20 – 19 – 18 – 17 – 16 – 15 – 14 – 13 – 12 – 11 – 10 – 9 – 8 – 7 – 6 – 5 – 4 – 3 – 2 – 1 – 0 – – – – CH3 CH2 CH1 CH0 • CHx: Channel x Disable 0 = No effect. 1 = Disables the corresponding channel. Warning: If the corresponding channel is disabled during a conversion or if it is disabled then reenabled during a conversion, its associated data and its corresponding EOC and OVRE flags in ADC_SR are unpredictable. 755 6384D–ATARM–04-May-09 40.6.5 Name: Access: 31 ADC Channel Status Register ADC_CHSR Read-only 30 29 28 27 26 25 24 – 23 – 22 – 21 – 20 – 19 – 18 – 17 – 16 – 15 – 14 – 13 – 12 – 11 – 10 – 9 – 8 – 7 – 6 – 5 – 4 – 3 – 2 – 1 – 0 – – – – CH3 CH2 CH1 CH0 • CHx: Channel x Status 0 = Corresponding channel is disabled. 1 = Corresponding channel is enabled. 756 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 40.6.6 Name: Access: 31 ADC Status Register ADC_SR Read-only 30 29 28 27 26 25 24 – 23 – 22 – 21 – 20 – 19 – 18 – 17 – 16 – 15 – 14 – 13 – 12 RXBUFF 11 ENDRX 10 GOVRE 9 DRDY 8 – 7 – 6 – 5 – 4 OVRE3 3 OVRE2 2 OVRE1 1 OVRE0 0 – – – – EOC3 EOC2 EOC1 EOC0 • EOCx: End of Conversion x 0 = Corresponding analog channel is disabled, or the conversion is not finished. 1 = Corresponding analog channel is enabled and conversion is complete. • OVREx: Overrun Error x 0 = No overrun error on the corresponding channel since the last read of ADC_SR. 1 = There has been an overrun error on the corresponding channel since the last read of ADC_SR. • DRDY: Data Ready 0 = No data has been converted since the last read of ADC_LCDR. 1 = At least one data has been converted and is available in ADC_LCDR. • GOVRE: General Overrun Error 0 = No General Overrun Error occurred since the last read of ADC_SR. 1 = At least one General Overrun Error has occurred since the last read of ADC_SR. • ENDRX: End of RX Buffer 0 = The Receive Counter Register has not reached 0 since the last write in ADC_RCR or ADC_RNCR. 1 = The Receive Counter Register has reached 0 since the last write in ADC_RCR or ADC_RNCR. • RXBUFF: RX Buffer Full 0 = ADC_RCR or ADC_RNCR have a value other than 0. 1 = Both ADC_RCR and ADC_RNCR have a value of 0. 757 6384D–ATARM–04-May-09 40.6.7 Name: Access: 31 ADC Last Converted Data Register ADC_LCDR Read-only 30 29 28 27 26 25 24 – 23 – 22 – 21 – 20 – 19 – 18 – 17 – 16 – 15 – 14 – 13 – 12 – 11 – 10 – 9 – 8 – 7 – 6 – 5 – 4 – 3 – 2 1 LDATA 0 LDATA • LDATA: Last Data Converted The analog-to-digital conversion data is placed into this register at the end of a conversion and remains until a new conversion is completed. 758 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 40.6.8 Name: Access: 31 ADC Interrupt Enable Register ADC_IER Write-only 30 29 28 27 26 25 24 – 23 – 22 – 21 – 20 – 19 – 18 – 17 – 16 – 15 – 14 – 13 – 12 RXBUFF 11 ENDRX 10 GOVRE 9 DRDY 8 – 7 – 6 – 5 – 4 OVRE3 3 OVRE2 2 OVRE1 1 OVRE0 0 – – – – EOC3 EOC2 EOC1 EOC0 • EOCx: End of Conversion Interrupt Enable x • OVREx: Overrun Error Interrupt Enable x • DRDY: Data Ready Interrupt Enable • GOVRE: General Overrun Error Interrupt Enable • ENDRX: End of Receive Buffer Interrupt Enable • RXBUFF: Receive Buffer Full Interrupt Enable 0 = No effect. 1 = Enables the corresponding interrupt. 759 6384D–ATARM–04-May-09 40.6.9 Name: Access: 31 ADC Interrupt Disable Register ADC_IDR Write-only 30 29 28 27 26 25 24 – 23 – 22 – 21 – 20 – 19 – 18 – 17 – 16 – 15 – 14 – 13 – 12 RXBUFF 11 ENDRX 10 GOVRE 9 DRDY 8 – 7 – 6 – 5 – 4 OVRE3 3 OVRE2 2 OVRE1 1 OVRE0 0 – – – – EOC3 EOC2 EOC1 EOC0 • EOCx: End of Conversion Interrupt Disable x • OVREx: Overrun Error Interrupt Disable x • DRDY: Data Ready Interrupt Disable • GOVRE: General Overrun Error Interrupt Disable • ENDRX: End of Receive Buffer Interrupt Disable • RXBUFF: Receive Buffer Full Interrupt Disable 0 = No effect. 1 = Disables the corresponding interrupt. 760 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 40.6.10 Name: Access: 31 ADC Interrupt Mask Register ADC_IMR Read-only 30 29 28 27 26 25 24 – 23 – 22 – 21 – 20 – 19 – 18 – 17 – 16 – 15 – 14 – 13 – 12 RXBUFF 11 ENDRX 10 GOVRE 9 DRDY 8 – 7 – 6 – 5 – 4 OVRE3 3 OVRE2 2 OVRE1 1 OVRE0 0 – – – – EOC3 EOC2 EOC1 EOC0 • EOCx: End of Conversion Interrupt Mask x • OVREx: Overrun Error Interrupt Mask x • DRDY: Data Ready Interrupt Mask • GOVRE: General Overrun Error Interrupt Mask • ENDRX: End of Receive Buffer Interrupt Mask • RXBUFF: Receive Buffer Full Interrupt Mask 0 = The corresponding interrupt is disabled. 1 = The corresponding interrupt is enabled. 761 6384D–ATARM–04-May-09 40.6.11 Name: Access: 31 ADC Channel Data Register ADC_CDRx Read-only 30 29 28 27 26 25 24 – 23 – 22 – 21 – 20 – 19 – 18 – 17 – 16 – 15 – 14 – 13 – 12 – 11 – 10 – 9 – 8 – 7 – 6 – 5 – 4 – 3 – 2 1 DATA 0 DATA • DATA: Converted Data The analog-to-digital conversion data is placed into this register at the end of a conversion and remains until a new conversion is completed. The Convert Data Register (CDR) is only loaded if the corresponding analog channel is enabled. 762 AT91SAM9G20 Preliminary 6384D–ATARM–04-May-09 AT91SAM9G20 Preliminary 41. AT91SAM9G20 Electrical Characteristics 41.1 Absolute Maximum Ratings Absolute Maximum Ratings* *NOTICE: Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or other conditions beyond those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Table 41-1. Operating Temperature (Industrial)............-40⋅ C to + 85⋅ C Junction Temperature ............................................... +125°C Storage Temperature ................................. -40°C to + 150°C Voltage on Input Pins with Respect to Ground .... -0.3V to VDDIO+0.3V (+4V max) Maximum Operating Voltage (VDDCORE, VDDPLL and VDDBU).............................. 1.2V Maximum Operating Voltage (VDDIOM and VDDIOP) ................................................ 4.0V Total DC Output Current on all I/O lines ................... 350 mA 763 6384D–ATARM–04-May-09 41.2 DC Characteristics The following characteristics are applicable to the operating temperature range: TA = -40°C to 85°C, unless otherwise specified. Table 41-2. Symbol VVDDCORE VVDDBU VVDDPLL VVDDOSC VVDDIOM VVDDIOP VVDDANA VVDDUSB VIL VIH DC Characteristics Parameter DC Supply Core DC Supply Backup DC Supply PLL DC Supply Oscillator DC Supply Memory I/Os DC Supply Peripheral I/Os DC Supply Analog DC Supply USB Input Low-level Voltage VVDDIO from 3.0V to 3.6V VVDDIO from 1.65V to 1.95V VVDDIO from 3.0V to 3.6V VVDDIO from 1.65V to 1.95V IO Max, VVDDIO from 3.0V to 3.6V CMOS (IO