AT89C51ID2-SLSIM

Features • 80C52 Compatible – 8051 Instruction Compatible – Six 8-bit I/O Ports (64 pins or 68 Pins Versions) – Four 8-bit I/O Ports (44 Pins Version) – Three 16-bit Timer/Counters – 256 bytes Scratch Pad RAM – 10 Interrupt Sources With 4 Priority Levels ISP (In-System Programming) Using Standard VCC Power Supply Integrated Power Monitor (POR/PFD) to Supervise Internal Power Supply Boot ROM Contains Low Level Flash Programming Routines and a Default Serial Loader High-speed Architecture – In Standard Mode: 40 MHz (Vcc 2.7V to 5.5V, Both Internal and External Code Execution) 60 MHz (Vcc 4.5V to 5.5V and Internal Code Execution Only) – In X2 Mode (6 Clocks/Machine Cycle) 20 MHz (Vcc 2.7V to 5.5V, Both Internal and External Code Execution) 30 MHz (Vcc 4.5V to 5.5V and Internal Code Execution Only) 64K bytes On-chip Flash Program/Data Memory – Byte and Page (128 bytes) Erase and Write – 100k Write Cycles On-chip 1792 bytes Expanded RAM (XRAM) – Software Selectable Size (0, 256, 512, 768, 1024, 1792 bytes) – 768 bytes Selected at Reset for T89C51RD2 Compatibility On-chip 2048 bytes EEPROM block for Data Storage – 100k Write Cycles Dual Data Pointer 32 KHz Crystal Oscillator Variable Length MOVX for Slow RAM/Peripherals Improved X2 Mode with Independant Selection for CPU and Each Peripheral Keyboard Interrupt Interface on Port 1 SPI Interface (Master/Slave Mode) 8-bit Clock Prescaler Two Wire Interface 400K bit/s Programmable Counter Array with: – High Speed Output – Compare/Capture – Pulse Width Modulator – Watchdog Timer Capabilities Asynchronous Port Reset Full Duplex Enhanced UART with Dedicated Internal Baud Rate Generator Low EMI (inhibit ALE) Hardware Watchdog Timer (One-time Enabled with Reset-Out), Power-Off Flag Power Control Modes: Idle Mode, Power-down Mode Power Supply: 2.7V to 5.5V Temperature Ranges: Industrial (-40 to +85°C) Packages: PLCC44, VQFP44, PLCC68(1), VQFP64(1) 1. Contact Atmel Sales for availability. • • • • 8-bit Flash Microcontroller AT89C51ID2 • • • • • • • • • • • • • • • • • • • • Note: Description AT89C51ID2 is a high performance CMOS Flash version of the 80C51 CMOS single chip 8-bit microcontroller. It contains a 64 Kbytes Flash memory block for program and for data. 4289A–8051–09/03 1 The 64 Kbytes Flash memory can be programmed either in parallel mode or in serial mode with the ISP capability or with software. The programming voltage is internally generated from the standard VCC pin. The AT89C51ID2 retains all features of the Atmel 80C52 with 256 bytes of internal RAM, a 10-source 4-level interrupt controller and three timer/counters. In addition, the AT89C51ID2 has a Programmable Counter Array, an XRAM of 1792 bytes, a Hardware Watchdog Timer, SPI and Keyboard, a more versatile serial channel that facilitates multiprocessor communication (EUART) and a speed improvement mechanism (X2 mode). The fully static design of the AT89C51ID2 allows to reduce system power consumption by bringing the clock frequency down to any value, even DC, without loss of data. The AT89C51ID2 has 2 software-selectable modes of reduced activity and 8-bit clock prescaler for further reduction in power consumption. In the Idle mode the CPU is frozen while the peripherals and the interrupt system are still operating. In the power-down mode the RAM is saved and all other functions are inoperative. The added features of the AT89C51ID2 make it more powerful for applications that need pulse width modulation, high speed I/O and counting capabilities such as alarms, motor control, corded phones, smart card readers. Table 1. Memory Size and I/O pins AT89C51ID2 PLCC44/VQFP44 PLCC68/VQFP64 (1) Flash (bytes) 64K 64K XRAM (bytes) 1792 1792 TOTAL RAM (bytes) 2048 2048 I/O 34 50 1. For PLCC68 and VQFP64 packages, please contact Atmel sales office for availability. 2 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Block Diagram Figure 1. Block Diagram T2EX PCA Keyboard (1) Keyboard Watch Dog E² DATA POR 2K x 8 PFD SPI BOOT Regulator 2K x8 POR / PFD ROM RxD TxD VCC Vss ECI (2) (2) XTALA1 XTALA2 XTALB1(1) XTALB2 ALE/ PROG PSEN EA RD WR (2) (2) Timer 0 Timer 1 INT Ctrl CPU C51 CORE (1) (1) (1) (1) EUART RAM 256x8 Flash 64Kx8 XRAM 1792 x 8 PCA Timer2 IB-bus Parallel I/O Ports & External Bus Port 0 Port 1Port 2 Port 3 Port4 Port 5 TWI (2) (2) T0 RESET T1 (2) (2) P1 P2 P0 P3 INT0 INT1 P4 P5 (3) (3) (1) (1)(1)(1) SDA SCL MISO MOSI SCK SS (1): Alternate function of Port 1 (2): Alternate function of Port 3 (3): Alternate function of Port I2 T2 3 4289A–8051–09/03 SFR Mapping The Special Function Registers (SFRs) of the AT89C51ID2 fall into the following categories: • • • • • • • • • • • • • • • • C51 core registers: ACC, B, DPH, DPL, PSW, SP I/O port registers: P0, P1, P2, P3, PI2 Timer registers: T2CON, T2MOD, TCON, TH0, TH1, TH2, TMOD, TL0, TL1, TL2, RCAP2L, RCAP2H Serial I/O port registers: SADDR, SADEN, SBUF, SCON PCA (Programmable Counter Array) registers: CCON, CCAPMx, CL, CH, CCAPxH, CCAPxL (x: 0 to 4) Power and clock control registers: PCON Hardware Watchdog Timer registers: WDTRST, WDTPRG Interrupt system registers: IE0, IPL0, IPH0, IE1, IPL1, IPH1 Keyboard Interface registers: KBE, KBF, KBLS SPI registers: SPCON, SPSTR, SPDAT 2-wire Interface registers: SSCON, SSCS, SSDAT, SSADR BRG (Baud Rate Generator) registers: BRL, BDRCON Flash register: FCON Clock Prescaler register: CKRL 32 kHz Sub Clock Oscillator registers: CKSEL, OSSCON Others: AUXR, AUXR1, CKCON0, CKCON1 4 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Table 2. C51 Core SFRs Mnemonic ACC B PSW SP DPL DPH Add E0h F0h D0h 81h 82h 83h Name Accumulator B Register Program Status Word Stack Pointer Data Pointer Low byte Data Pointer High byte CY AC F0 RS1 RS0 OV F1 P 7 6 5 4 3 2 1 0 Table 3. System Management SFRs Mnemonic PCON AUXR Add 87h 8Eh Name Power Control Auxiliary Register 0 7 SMOD1 6 SMOD0 5 M0 ENBOO T 4 POF XRS2 3 GF1 XRS1 2 GF0 XRS0 1 PD EXTRA M OscBEn 0 IDL AO AUXR1 CKRL CKSEL OSCON A2h 97h 85h 86h Auxiliary Register 1 Clock Reload Register Clock Selection Register Oscillator Control Register - - - GF3 - 0 SCLKT0 DPS CKS OscAEn Table 4. Interrupt SFRs Mnemonic IEN0 IEN1 IPH0 IPL0 IPH1 IPL1 Add A8h B1h B7h B8h B3h B2h Name Interrupt Enable Control 0 Interrupt Enable Control 1 Interrupt Priority Control High 0 Interrupt Priority Control Low 0 Interrupt Priority Control High 1 Interrupt Priority Control Low 1 7 EA 6 EC PPCH PPCL 5 ET2 PT2H PT2L 4 ES PSH PSL 3 ET1 PT1H PT1L 2 EX1 ESPI PX1H PX1L SPIH SPIL 1 ET0 EI2C PT0H PT0L IE2CH IE2CL 0 EX0 EKBD PX0H PX0L KBDH KBDL 5 4289A–8051–09/03 Table 5. Port SFRs Mnemonic P0 P1 P2 P3 P4 P5 Add 80h 90h A0h B0h C0h E8h Name 8-bit Port 0 8-bit Port 1 8-bit Port 2 8-bit Port 3 8-bit Port 4 8-bit Port 5 7 6 5 4 3 2 1 0 Table 6. Flash and EEPROM Data Memory SFR Mnemonic FCON EECON Add D1h Name Flash Control EEPROM data Control 7 FPL3 6 FPL2 5 FPL1 4 FPL0 3 FPS 2 FMOD1 1 FMOD0 0 FBUSY Table 7. Timer SFRs Mnemonic TCON TMOD TL0 TH0 TL1 TH1 WDTRST WDTPRG T2CON T2MOD RCAP2H Add 88h 89h 8Ah 8Ch 8Bh 8Dh A6h A7h C8h C9h CBh Name Timer/Counter 0 and 1 Control Timer/Counter 0 and 1 Modes Timer/Counter 0 Low Byte Timer/Counter 0 High Byte Timer/Counter 1 Low Byte Timer/Counter 1 High Byte WatchDog Timer Reset WatchDog Timer Program Timer/Counter 2 control Timer/Counter 2 Mode Timer/Counter 2 Reload/Capture High byte Timer/Counter 2 Reload/Capture Low byte Timer/Counter 2 High Byte Timer/Counter 2 Low Byte TF2 EXF2 RCLK TCLK EXEN2 WTO2 TR2 WTO1 C/T2# T2OE WTO0 CP/RL2# DCEN 7 TF1 GATE1 6 TR1 C/T1# 5 TF0 M11 4 TR0 M01 3 IE1 GATE0 2 IT1 C/T0# 1 IE0 M10 0 IT0 M00 RCAP2L TH2 TL2 CAh CDh CCh 6 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Table 8. PCA SFRs Mnemo -nic CCON CMOD CL CH Add Name D8h D9h E9h F9h PCA Timer/Counter Control PCA Timer/Counter Mode PCA Timer/Counter Low byte PCA Timer/Counter High byte ECOM0 ECOM1 ECOM2 ECOM3 ECOM4 CAPP0 CAPP1 CAPP2 CAPP3 CAPP4 CAPN0 CAPN1 CAPN2 CAPN3 CAPN4 MAT0 MAT1 MAT2 MAT3 MAT4 TOG0 TOG1 TOG2 TOG3 TOG4 PWM0 PWM1 PWM2 PWM3 PWM4 ECCF0 ECCF1 ECCF2 ECCF3 ECCF4 7 CF CIDL 6 CR WDTE 5 4 CCF4 3 CCF3 2 CCF2 CPS1 1 CCF1 CPS0 0 CCF0 ECF CCAPM0 DAh PCA Timer/Counter Mode 0 CCAPM1 DBh PCA Timer/Counter Mode 1 CCAPM2 DCh PCA Timer/Counter Mode 2 CCAPM3 DDh PCA Timer/Counter Mode 3 CCAPM4 DEh PCA Timer/Counter Mode 4 CCAP0H FAh CCAP1H FBh PCA Compare Capture Module 0 H CCAP0H7 CCAP0H6 CCAP0H5 CCAP0H4 CCAP0H3 CCAP0H2 CCAP0H1 CCAP0H0 PCA Compare Capture Module 1 H CCAP1H7 CCAP1H6 CCAP1H5 CCAP1H4 CCAP1H3 CCAP1H2 CCAP1H1 CCAP1H0 CCAP2H FCh PCA Compare Capture Module 2 H CCAP2H7 CCAP2H6 CCAP2H5 CCAP2H4 CCAP2H3 CCAP2H2 CCAP2H1 CCAP2H0 CCAP3H FDh PCA Compare Capture Module 3 H CCAP3H7 CCAP3H6 CCAP3H5 CCAP3H4 CCAP3H3 CCAP3H2 CCAP3H1 CCAP3H0 CCAP4H FEh CCAP0L CCAP1L CCAP2L CCAP3L CCAP4L PCA Compare Capture Module 4 H CCAP4H7 CCAP4H6 CCAP4H5 CCAP4H4 CCAP4H3 CCAP4H2 CCAP4H1 CCAP4H0 CCAP0L6 CCAP1L6 CCAP2L6 CCAP3L6 CCAP4L6 CCAP0L5 CCAP0L4 CCAP1L5 CCAP1L4 CCAP2L5 CCAP2L4 CCAP3L5 CCAP3L4 CCAP4L5 CCAP4L4 CCAP0L3 CCAP0L2 CCAP1L3 CCAP1L2 CCAP2L3 CCAP2L2 CCAP3L3 CCAP3L2 CCAP4L3 CCAP4L2 CCAP0L1 CCAP1L1 CCAP2L1 CCAP3L1 CCAP4L1 CCAP0L0 CCAP1L0 CCAP2L0 CCAP3L0 CCAP4L0 EAh PCA Compare Capture Module 0 L CCAP0L7 EBh PCA Compare Capture Module 1 L CCAP1L7 ECh PCA Compare Capture Module 2 L CCAP2L7 EDh PCA Compare Capture Module 3 L CCAP3L7 EEh PCA Compare Capture Module 4 L CCAP4L7 Table 9. Serial I/O Port SFRs Mnemonic SCON SBUF SADEN SADDR BDRCON BRL Add 98h 99h B9h A9h 9Bh 9Ah Name Serial Control Serial Data Buffer Slave Address Mask Slave Address Baud Rate Control Baud Rate Reload BRR TBCK RBCK SPD SRC 7 FE/SM0 6 SM1 5 SM2 4 REN 3 TB8 2 RB8 1 TI 0 RI Table 10. SPI Controller SFRs Mnemonic SPCON SPSTA SPDAT Add C3h C4h C5h Name SPI Control SPI Status SPI Data 7 SPR2 SPIF SPD7 6 SPEN WCOL SPD6 5 SSDIS SSERR SPD5 4 MSTR MODF SPD4 3 CPOL SPD3 2 CPHA SPD2 1 SPR1 SPD1 0 SPR0 SPD0 7 4289A–8051–09/03 Table 11. Two-Wire Interface Controller SFRs Mnemonic SSCON SSCS SSDAT SSADR Add 93h 94h 95h 96h Name Synchronous Serial control Synchronous Serial Status Synchronous Serial Data Synchronous Serial Address 7 SSCR2 SSC4 SSD7 SSA7 6 SSPE SSC3 SSD6 SSA6 5 SSSTA SSC2 SSD5 SSA5 4 SSSTO SSC1 SSD4 SSA4 3 SSI SSC0 SSD3 SSA3 2 SSAA 0 SSD2 SSA2 1 SSCR1 0 SSD1 SSA1 0 SSCR0 0 SSD0 SSGC Table 12. Keyboard Interface SFRs Mnemonic KBLS KBE KBF Add 9Ch 9Dh 9Eh Name Keyboard Level Selector Keyboard Input Enable Keyboard Flag Register 7 KBLS7 KBE7 KBF7 6 KBLS6 KBE6 KBF6 5 KBLS5 KBE5 KBF5 4 KBLS4 KBE4 KBF4 3 KBLS3 KBE3 KBF3 2 KBLS2 KBE2 KBF2 1 KBLS1 KBE1 KBF1 0 KBLS0 KBE0 KBF0 8 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Table below shows all SFRs with their address and their reset value. Table 13. SFR Mapping Bit addressable 0/8 F8h PI2 XXXX XX11 B 0000 0000 P5 bit addressable 1111 1111 E0h ACC 0000 0000 CCON 00X0 0000 PSW 0000 0000 T2CON 0000 0000 P4 1111 1111 IPL0 X000 000 P3 1111 1111 IEN0 0000 0000 P2 1111 1111 SCON 0000 0000 P1 1111 1111 TCON 0000 0000 P0 1111 1111 0/8 TMOD 0000 0000 SP 0000 0111 1/9 TL0 0000 0000 DPL 0000 0000 2/A SBUF XXXX XXXX SADEN 0000 0000 IEN1 XXXX X000 SADDR 0000 0000 AUXR1 XXXX X0X0 BRL 0000 0000 BDRCON XXX0 0000 SSCON 0000 0000 TL1 0000 0000 DPH 0000 0000 3/B 4/C KBLS 0000 0000 SSCS 1111 1000 TH0 0000 0000 KBE 0000 0000 SSDAT 1111 1111 TH1 0000 0000 CKSEL XXXX XXX0 5/D WDTRST XXXX XXXX KBF 0000 0000 SSADR 1111 1110 AUXR XX00 1000 OSSCON XXXX X001 6/E CKRL 1111 1111 CKCON0 0000 0000 PCON 00X1 0000 7/F IPL1 XXXX X000 IPH1 XXXX X111 IPH0 X000 0000 CKCON1 XXXX XXX0 WDTPRG XXXX X000 CMOD 00XX X000 FCON (1) XXXX 0000 T2MOD XXXX XX00 CCAPM0 X000 0000 EECON xxxx xx00 RCAP2L 0000 0000 RCAP2H 0000 0000 SPCON 0001 0100 TL2 0000 0000 SPSTA 0000 0000 TH2 0000 0000 SPDAT XXXX XXXX P5 byte Addressable 1111 1111 BFh CCAPM1 X000 0000 CCAPM2 X000 0000 CCAPM3 X000 0000 CCAPM4 X000 0000 CL 0000 0000 CCAP0L XXXX XXXX CCAP1L XXXX XXXX CCAP2L XXXX XXXX CCAP3L XXXX XXXX CCAP4L XXXX XXXX 1/9 CH 0000 0000 2/A CCAP0H XXXX XXXX 3/B CCAP1H XXXX XXXX Non Bit addressable 4/C CCAP2H XXXX XXXX 5/D CCAP3H XXXX XXXX 6/E CCAP4H XXXX XXXX 7/F FFh F0h F7h E8h EFh E7h D8h DFh D0h D7h C8h CFh C0h C7h B8h B0h B7h A8h AFh A0h A7h 98h 9Fh 90h 97h 88h 8Fh 80h 87h Reserved 9 4289A–8051–09/03 Pin Configurations P1.0/T2/XTALB1 P1.1/T2EX/SS P1.4/CEX1 P1.3/CEX0 6 5 4 3 2 1 44 43 42 41 40 P1.5/CEX2/MISO P1.6/CEX3/SCK P1.7/CEx4/MOSI RST P3.0/RxD PI2.1/SDA P3.1/TxD P3.2/INT0 P3.3/INT1 P3.4/T0 P3.5/T1 7 8 9 10 11 12 13 14 15 16 17 39 38 37 36 35 34 33 32 31 30 29 P0.4/AD4 P0.5/AD5 P0.6/AD6 P0.7/AD7 EA PI2.0/SCL ALE/PROG PSEN P2.7/A15 P2.6/A14 P2.5/A13 AT89C51ID2 PLCC44 18 19 20 21 22 23 24 25 26 27 28 P3.6/WR P2.2/A10 P2.3/A11 P2.4/A12 P3.7/RD XTAL2 NIC* P2.0/A8 P2.1/A9 XTAL1 VSS P0.2/AD2 P0.3/AD3 P0.0/AD0 P0.1/AD1 P1.2/ECI XTALB2 VCC P1.0/T2/XTALB1 P1.1/T2EX/SS P1.4/CEX1 P1.3/CEX0 P0.0/AD0 P0.1/AD1 P0.2/AD2 44 43 42 41 40 39 38 37 36 35 34 P1.5/CEX2/MISO P1.6/CEX3/SCK P1.7/CEX4/MOSI RST P3.0/RxD PI2.1/SDA P3.1/TxD P3.2/INT0 P3.3/INT1 P3.4/T0 P3.5/T1 1 2 3 4 5 6 7 8 9 10 11 33 32 31 30 29 28 27 26 25 24 23 P0.4/AD4 P0.5/AD5 P0.6/AD6 P0.7/AD7 EA PI2.0/SCL ALE/PROG PSEN P2.7/A15 P2.6/A14 P2.5/A13 AT89C51ID2 VQFP44 1.4 12 13 14 15 16 17 18 19 20 21 22 P2.3/A11 P2.4/A12 XTAL1 P2.2/A10 NIC* P2.0/A8 P3.6/WR P3.7/RD P2.1/A9 XTAL2 VSS 10 AT89C51ID2 4289A–8051–09/03 P0.3/AD3 P1.2/ECI XTALB2 VCC AT89C51ID2 9 8 7 6 5 4 3 2 1 68 67 66 65 64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 45 44 P0.4/AD4 P5.4 P5.3 P0.5/AD5 P0.6/AD6 NIC P0.7/AD7 EA# PI2.0/SCL ALE PSEN# NIC P2.7/A15 P2.6/A14 P5.2 P5.1 P2.5/A13 P5.5 P0.3/AD3 P0.2/AD2 P5.6 P0.1/AD1 P0.0/AD0 P5.7 VCC XTALB2 P1.0/T2/XTALB1 P4.0 P1.1/T2EX/SS# P1.2/ECI P1.3/CEX0 P4.1 P1.4/CEX1 P4.2 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 AT89C51ID2 PLCC68 P5.0 P2.4/A12 P2.3/A11 P4.7 P2.2/A10 P2.1/A9 P2.0/A8 P4.6 NIC VSS P4.5 XTAL1 XTAL2 P3.7/RD# P4.4 P3.6/WR# P4.3 64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 P0.4/AD4 P5.4 P5.3 P0.5/AD5 P0.6/AD6 P0.7/AD7 EA# PI2.0/SCL ALE PSEN# P2.7/A15 P2.6/A14 P5.2 P5.1 P2.5/A13 P5.0 P5.5 P0.3/AD3 P0.2/AD2 P5.6 P0.1/AD1 P0.0/AD0 P5.7 VCC XTALB2 P1.0/T2/XTALB1 P4.0 P1.1/T2EX/SS# P1.2/ECI P1.3/CEX0 P4.1 P1.4/CEX1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 AT89C51ID2 VQFP64 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 P2.4/A12 P2.3/A11 P4.7 P2.2/A10 P2.1/A9 P2.0/A8 P4.6 NIC VSS P4.5 XTAL1 XTAL2 P3.7/RD# P4.4 P3.6/WR# P4.3 P4.2 P1.5/CEX2/MISO P1.6/CEX3/SCK P1.7/A17/CEX4/MOSI RST NIC NIC NIC P3.0/RxD SDA NIC P3.1/TxD P3.2/INT0# P3.3/INT1# P3.4/T0 P3.5/T1 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 P1.5/CEX2/MISO P1.6/CEX3/SCK P1.7/CEX4/MOSI RST NIC NIC NIC P3.0/RxD NIC SDA NIC NIC P3.1/TxD P3.2/INT0# P3.3/INT1# P3.4/T0 P3.5/T1 NIC: Not Internaly Connected 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 11 4289A–8051–09/03 Table 14. Pin Description Pin Number Type Mnemonic VSS VCC P0.0 - P0.7 PLCC44 22 44 43 - 36 VQFP44 16 38 37 - 30 15, 14, 12, 11, 9,6, 5, 3 6, 5, 3, 2, 64, 61,60,59 PLCC68 51 17 VQFP64 40 8 I I Name and Function Ground: 0V reference Power Supply: This is the power supply voltage for normal, idle and power-down operation Port 0: Port 0 is an open-drain, bidirectional I/O port. Port 0 pins that have 1s written to them float and can be used as high impedance inputs. Port 0 must be polarized to VCC or VSS in order to prevent any parasitic current consumption. Port 0 is also the multiplexed low-order address and data bus during access to external program and data memory. In this application, it uses strong internal pull-up when emitting 1s. Port 0 also inputs the code bytes during EPROM programming. External pull-ups are required during program verification during which P0 outputs the code bytes. Port 1: Port 1 is an 8-bit bidirectional I/O port with internal pull-ups. Port 1 pins that have 1s written to them are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 1 pins that are externally pulled low will source current because of the internal pull-ups. Port 1 also receives the low-order address byte during memory programming and verification. Alternate functions for AT89C51ID2 Port 1 include: 2 40 19 10 I/O I/O I 3 41 21 12 I/O I I 4 42 22 13 I/O I 5 43 23 14 I/O I/O 6 44 25 16 I/O I/O 7 1 27 18 I/O I/O I/O P1.0: Input/Output T2 (P1.0): Timer/Counter 2 external count input/Clockout XTALB1 (P1.0): Sub Clock input to the inverting oscillator amplifier P1.1: Input/Output T2EX: Timer/Counter 2 Reload/Capture/Direction Control SS: SPI Slave Select P1.2: Input/Output ECI: External Clock for the PCA P1.3: Input/Output CEX0: Capture/Compare External I/O for PCA module 0 P1.4: Input/Output CEX1: Capture/Compare External I/O for PCA module 1 P1.5: Input/Output CEX2: Capture/Compare External I/O for PCA module 2 MISO: SPI Master Input Slave Output line When SPI is in master mode, MISO receives data from the slave peripheral. When SPI is in slave mode, MISO outputs data to the master controller. 8 2 28 19 I/O I/O I/O 9 3 29 20 I/O P1.6: Input/Output CEX3: Capture/Compare External I/O for PCA module 3 SCK: SPI Serial Clock P1.7: Input/Output: I/O P1.0 - P1.7 2-9 40 - 44 1-3 19, 21, 22, 23, 25, 27, 28, 29 10, 12, 13, 14, 16, 18, 19, 20 I/O 12 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Table 14. Pin Description (Continued) Pin Number Type Mnemonic PLCC44 VQFP44 PLCC68 VQFP64 I/O I/O Name and Function CEX4: Capture/Compare External I/O for PCA module 4 MOSI: SPI Master Output Slave Input line When SPI is in master mode, MOSI outputs data to the slave peripheral. When SPI is in slave mode, MOSI receives data from the master controller. XTALA1 XTALA2 XTALB1 21 20 2 15 14 40 49 48 10 38 37 19 I O I Crystal A 1: Input to the inverting oscillator amplifier and input to the internal clock generator circuits. Crystal A 2: Output from the inverting oscillator amplifier Crystal B 1: (Sub Clock) Input to the inverting oscillator amplifier and input to the internal clock generator circuits. Crystal B 2: (Sub Clock) Output from the inverting oscillator amplifier Port 2: Port 2 is an 8-bit bidirectional I/O port with internal pull-ups. Port 2 pins that have 1s written to them are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 2 pins that are externally pulled low will source current because of the internal pull-ups. Port 2 emits the high-order address byte during fetches from external program memory and during accesses to external data memory that use 16-bit addresses (MOVX @DPTR).In this application, it uses strong internal pull-ups emitting 1s. During accesses to external data memory that use 8-bit addresses (MOVX @Ri), port 2 emits the contents of the P2 SFR. Port 3: Port 3 is an 8-bit bidirectional I/O port with internal pull-ups. Port 3 pins that have 1s written to them are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 3 pins that are externally pulled low will source current because of the internal pull-ups. Port 3 also serves the special features of the 80C51 family, as listed below. RXD (P3.0): Serial input port TXD (P3.1): Serial output port INT0 (P3.2): External interrupt 0 INT1 (P3.3): External interrupt 1 T0 (P3.4): Timer 0 external input T1 (P3.5): Timer 1 external input WR (P3.6): External data memory write strobe RD (P3.7): External data memory read strobe Port 4: Port 4 is an 8-bit bidirectional I/O port with internal pull-ups. Port 5 pins that have 1s written to them are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 4 pins that are externally pulled low will source current because of the internal pull-ups. Port 5: Port 5 is an 8-bit bidirectional I/O port with internal pull-ups. Port 3 pins that have 1s written to them are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 5 pins that are externally pulled low will source current because of the internal pull-ups. XTALB2 P2.0 - P2.7 1 24 - 31 39 18 - 25 9 18 O 54, 55, 56, 58, 59, 61, 64, 65 43, 44, 45, 47, 48, 50, 53, 54 I/O P3.0 - P3.7 11, 13 - 19 5, 7 - 13 34, 39, 40, 41, 42, 43, 45, 47 25, 28, 29, 30, 31, 32, 34, 36 I/O 11 13 14 15 16 17 18 19 5 7 8 9 10 11 12 13 34 39 40 41 42 43 45 47 20, 24, 26, 44, 46, 50, 53, 57 60, 62, 63, 7, 8, 10, 13, 16 25 28 29 30 31 32 34 36 11, 15, 17,33, 35,39, 42, 46 49, 51, 52, 62, 63, 1, 4, 7 I O I I I I O O P4.0 - P4.7 - - I/O P5.0 - P5.7 - - I/O 13 4289A–8051–09/03 Table 14. Pin Description (Continued) Pin Number Type Mnemonic PI2.0 - PI2.1 PLCC44 VQFP44 PLCC68 VQFP64 Name and Function Port I2: Port I2 is an open drain. It can be used as inputs (must be polarized to Vcc with external resistor to prevent any parasitic current consumption). I/O SCL (PI2.0): 2-wire Serial Clock SCL output the serial clock to slave peripherals SCL input the serial clock from master SDA (PI2.1): 2-wire Serial Data 12 6 36 26 I/O SDA is the bidirectional 2-wire data line Reset: A high on this pin for two machine cycles while the oscillator is running, resets the device. An internal diffused resistor to VSS permits a poweron reset using only an external capacitor to VCC. This pin is an output when the hardware watchdog forces a system reset. Address Latch Enable/Program Pulse: Output pulse for latching the low byte of the address during an access to external memory. In normal operation, ALE is emitted at a constant rate of 1/6 (1/3 in X2 mode) the oscillator frequency, and can be used for external timing or clocking. Note that one ALE pulse is skipped during each access to external data memory. This pin is also the program pulse input (PROG) during Flash programming. ALE can be disabled by setting SFR’s AUXR.0 bit. With this bit set, ALE will be inactive during internal fetches. Program Strobe ENable: The read strobe to external program memory. When executing code from the external program memory, PSEN is activated twice each machine cycle, except that two PSEN activations are skipped during each access to external data memory. PSEN is not activated during fetches from internal program memory. External Access Enable: EA must be externally held low to enable the device to fetch code from external program memory locations 0000H to FFFFH. If security level 1 is programmed, EA will be internally latched on Reset. 34, 12 28, 6 1, 36 57, 26 34 28 1 57 RST 10 4 30 21 I ALE/PROG 33 27 68 56 O (I) PSEN 32 26 67 55 O EA 35 29 2 58 I 14 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Oscillators Overview Two oscillators are available for CPU: • • • • OSCA used for high frequency: Up to 40 MHz OSCB used for low frequency: 32.768 kHz to switch OSCA to OSCB and vice-versa to stop OSCA or OSCB to reduce consumption Several operating modes are available and programmable by software: In order to optimize the power consumption and the execution time needed for a specific task, an internal prescaler feature has been implemented between the selected oscillator and the CPU. Registers Table 15. CKSEL Register CKSEL - Clock Selection Register (85h) 7 Bit Number 7 6 5 4 3 2 1 6 Bit Mnemonic Description Reserved Reserved Reserved Reserved Reserved Reserved Reserved CPU Oscillator Select Bit: (CKS) Cleared, CPU and peripherals connected to OSCB 0 CKS Set, CPU and peripherals connected to OSCA Programmed by hardware after a Power-up regarding Hardware Security Byte (HSB).HSB.OSC (Default setting, OSCA selected) 5 4 3 2 1 0 CKS Reset Value = 0000 000’HSB.OSC’b (see Hardware Security Byte (HSB)) Not bit addressable 15 4289A–8051–09/03 Table 16. OSCCON Register OSCCON- Oscillator Control Register (86h) 7 Bit Number 7 6 5 4 3 6 Bit Mnemonic Description Reserved Reserved Reserved Reserved Reserved Sub Clock Timer0 2 SCLKT0 Cleared by software to select T0 pin Set by software to select T0 Sub Clock Cleared by hardware after a Power Up OscB enable bit Set by software to run OscB 1 OscBEn Cleared by software to stop OscB Programmed by hardware after a Power-up regarding HSB.OSC (Default cleared, OSCB stopped) OscA enable bit Set by software to run OscA 0 OscAEn Cleared by software to stop OscA Programmed by hardware after a Power-up regarding HSB.OSC(Default Set, OSCA runs) 5 4 3 2 SCLKT0 1 OscBEn 0 OscAEn Reset Value = XXXX X0’HSB.OSC’’HSB.OSC’b (see Hardware Security Byte (HSB)) Not bit addressable Table 17. CKRL Register CKRL - Clock Reload Register 7 Bit Number 7:0 6 5 4 3 2 1 0 - Mnemonic Description CKRL Clock Reload Register: Prescaler value Reset Value = 1111 1111b Not bit addressable 16 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Table 18. PCON Register PCON - Power Control Register (87h) 7 SMOD1 Bit Number 7 6 SMOD0 Bit Mnemonic Description SMOD1 Serial port Mode bit 1 Set to select double baud rate in mode 1, 2 or 3. Serial port Mode bit 0 Cleared to select SM0 bit in SCON register. Set to select FE bit in SCON register. Reserved The value read from this bit is indeterminate. Do not set this bit. Power-Off Flag Cleared to recognize next reset type. Set by hardware when VCC rises from 0 to its nominal voltage. Can also be set by software. General purpose Flag Cleared by software for general purpose usage. Set by software for general purpose usage. General purpose Flag Cleared by software for general purpose usage. Set by software for general purpose usage. Power-Down mode bit Cleared by hardware when reset occurs. Set to enter power-down mode. Idle mode bit Cleared by hardware when interrupt or reset occurs. Set to enter idle mode. 5 4 POF 3 GF1 2 GF0 1 PD 0 IDL 6 SMOD0 5 - 4 POF 3 GF1 2 GF0 1 PD 0 IDL Reset Value = 00X1 0000b Not bit addressable 17 4289A–8051–09/03 Functional Block Diagram Figure 2. Functional Oscillator Block Diagram PwdOscA Reset CKRL XtalA1 OscA XtalA2 :2 OscAEn OSCCON FOSCA 1 0 8-bit Prescaler-Divider Reload 0 1 1 0 CKRL=0xFF? FOSCB CKS CKSEL Idle CLK Peripheral Clock PERIPH CLK CPU CPU clock X2 CKCON0 PwdOscB XtalB1 XtalB2 OscB :128 Sub Clock OscBEn OSCCON Operating Modes Reset A hardware RESET puts the Clock generator in the following state: The selected oscillator depends on OSC bit in Hardware Security Byte (HSB). HSB.OSC = 1 (Oscillator A selected) • • • • Functional Modes Normal Modes • • • CPU and Peripherals clock depend on the software selection using CKCON0, CKCON1 and CKRL registers CKS bit in CKSEL register selects either OscA or OscB CKRL register determines the frequency of the OscA clock. OscAEn = 1 & OscBEn = 0: OscA is running, OscB is stopped. CKS = 1: OscA is selected for CPU. OscAEn = 0 & OscBEn = 1: OscB is running, OscA is stopped. CKS = 0: OscB is selected for CPU. HSB.OSC = 0 (Oscillator B selected) 18 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 • It is always possible to switch dynamically by software from OscA to OscB, and vice versa by changing CKS bit. IDLE modes are achieved by using any instruction that writes into PCON.0 bit (IDL) IDLE modes A and B depend on previous software sequence, prior to writing into PCON.0 bit: IDLE MODE A: OscA is running (OscAEn = 1) and selected (CKS = 1) IDLE MODE B: OscB is running (OscBEn = 1) and selected (CKS = 0) The unused oscillator OscA or OscB can be stopped by software by clearing OscAEn or OscBEn respectively. IDLE mode can be canceled either by Reset, or by activation of any enabled interruption In both cases, PCON.0 bit (IDL) is cleared by hardware Exit from IDLE modes will leave Oscillators control bits (OscEnA, OscEnB, CKS) unchanged. POWER DOWN modes are achieved by using any instruction that writes into PCON.1 bit (PD) POWER DOWN modes A and B depend on previous software sequence, prior to writing into PCON.1 bit: Both OscA and OscB will be stopped. POWER DOWN mode can be cancelled either by a hardware Reset, an external interruption, or the keyboard interrupt. By Reset signal: The CPU will restart according to OSC bit in Hardware Security Bit (HSB) register. By INT0 or INT1 interruption, if enabled: (standard behavioral), request on Pads must be driven low enough to ensure correct restart of the oscillator which was selected when entering in Power down. By keyboard Interrupt if enabled: a hardware clear of the PCON.1 flag ensure the restart of the oscillator which was selected when entering in Power down. Idle Modes • • • • • • • • Power Down Modes • • • • • • • Table 19. Overview PCON.1 0 PCON.0 0 OscBEn 0 OscAEn 1 CKS 1 Selected Mode NORMAL MODE A, OscB stopped NORMAL MODE A, OscB running NORMAL MODE B, OscA stopped NORMAL MODE B, OscA running INVALID Comment Default mode after power-up or Warm Reset Default mode after power-up or Warm Reset + OscB running OscB running and selected OscB running and selected + OscA running OscA & OscB cannot be stopped at the same time OscA must not be stopped, as used for CPU and peripherals OscB must not be stopped as used for CPU and peripherals 0 0 1 1 1 0 0 1 0 0 0 0 1 1 0 X X 0 0 X X X X 0 1 INVALID X X 0 X 0 INVALID 19 4289A–8051–09/03 Table 19. Overview (Continued) PCON.1 PCON.0 OscBEn OscAEn CKS Selected Mode Comment The CPU is off, OscA supplies the peripherals, OscB can be disabled (OscBEn = 0) The CPU is off, OscB supplies the peripherals, OscA can be disabled (OscAEn = 0) The CPU and peripherals are off, OscA and OscB are stopped 0 1 X 1 1 IDLE MODE A 0 1 1 X 0 IDLE MODE B 1 X X 1 X POWER DOWN MODE Design Considerations Oscillators Control • • • • PwdOscA and PwdOscB signals are generated in the Clock generator and used to control the hard blocks of oscillators A and B. PwdOscA =’1’ stops OscA PwdOscB =’1’ stops OscB The following tables summarize the Operating modes: PCON.1 0 1 OscAEn 1 X PwdOscA 0 1 Comments OscA running OscA stopped by Power-down mode OscA stopped by clearing OscAEn Comments OscB running OscB stopped by Power-down mode OscB stopped by clearing OscBEn 0 0 1 PCON.1 0 1 OscBEn 1 X PwdOscB 0 1 0 0 1 Prescaler Divider • • • A hardware RESET puts the prescaler divider in the following state: – CKRL = FFh: FCLK CPU = FCLK PERIPH = FOSCA/2 (Standard C51 feature) CKS signal selects OSCA or OSCB: FCLK OUT = FOSCA or FOSCB Any value between FFh down to 00h can be written by software into CKRL register in order to divide frequency of the selected oscillator: – CKRL = 00h: minimum frequency FCLK CPU = FCLK PERIPH = FOSCA/1020 (Standard Mode) FCLK CPU = FCLK PERIPH = FOSCA/510 (X2 Mode) CKRL = FFh: maximum frequency FCLK CPU = FCLK PERIPH = FOSCA/2 (Standard Mode) FCLK CPU = FCLK PERIPH = FOSCA (X2 Mode) – 20 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 – FCLK CPU and FCLK PERIPH, for CKRL0xFF In X2 Mode: F OSCA F CPU = F CLKPERIPH = ---------------------------------------------In X1 Mode: F OSCA F CPU = F CLKPERIPH = ---------------------------------------------4 × ( 255 – CKRL ) 2 × ( 255 – CKRL ) Timer 0: Clock Inputs Figure 3. Timer 0: Clock Inputs FCLK PERIPH T0 pin Sub Clock :6 0 1 C/T TMOD SCLKT0 OSCCON Gate INT0 TR0 0 1 Control Timer 0 Note: The SCLKT0 bit in OSCCON register allows to select Timer 0 Subsidiary clock. SCLKT0 = 0: Timer 0 uses the standard T0 pin as clock input (Standard mode) SCLKT0 = 1: Timer 0 uses the special Sub Clock as clock input, this feature can be use as periodic interrupt for time clock. 21 4289A–8051–09/03 Enhanced Features In comparison to the original 80C52, the AT89C51ID2 implements some new features, which are: • • • • • • • • • • • X2 option Dual Data Pointer Extended RAM Programmable Counter Array (PCA) Hardware Watchdog SPI interface 4-level interrupt priority system power-off flag ONCE mode ALE disabling Enhanced features on the UART and the timer 2 X2 Feature T he AT89C51ID2 core needs only 6 clock periods per machine cycle. This feature called ‘X2’ provides the following advantages: • • • • Divide frequency crystals by 2 (cheaper crystals) while keeping same CPU power. Save power consumption while keeping same CPU power (oscillator power saving). Save power consumption by dividing dynamically the operating frequency by 2 in operating and idle modes. Increase CPU power by 2 while keeping same crystal frequency. In order to keep the original C51 compatibility, a divider by 2 is inserted between the XTAL1 signal and the main clock input of the core (phase generator). This divider may be disabled by software. Description The clock for the whole circuit and peripherals is first divided by two before being used by the CPU core and the peripherals. This allows any cyclic ratio to be accepted on XTAL1 input. In X2 mode, as this divider is bypassed, the signals on XTAL1 must have a cyclic ratio between 40 to 60%. Figure 4 shows the clock generation block diagram. X2 bit is validated on the rising edge of the XTAL1÷2 to avoid glitches when switching from X2 to STD mode. Figure 5 shows the switching mode waveforms. Figure 4. Clock Generation Diagram CKRL XTAL1 FXTAL 2 XTAL1:2 0 1 FOSC 8 bit Prescaler FCLK CPU FCLK PERIPH X2 CKCON0 22 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Figure 5. Mode Switching Waveforms XTAL1 XTAL1:2 X2 bit CPU clock STD Mode FOSC X2 Mode STD Mode The X2 bit in the CKCON0 register (see Table 20) allows a switch from 12 clock periods per instruction to 6 clock periods and vice versa. At reset, the speed is set according to X2 bit of Hardware Security Byte (HSB). By default, Standard mode is active. Setting the X2 bit activates the X2 feature (X2 mode). The T0X2, T1X2, T2X2, UartX2, PcaX2, and WdX2 bits in the CKCON0 register (See Table 20.) and SPIX2 bit in the CKCON1 register (see Table 21) allows a switch from standard peripheral speed (12 clock periods per peripheral clock cycle) to fast peripheral speed (6 clock periods per peripheral clock cycle). These bits are active only in X2 mode. 23 4289A–8051–09/03 Table 20. CKCON0 Register CKCON0 - Clock Control Register (8Fh) 7 TWIX2 Bit Number 6 WDX2 Bit Mnemonic Description 2-wire clock (This control bit is validated when the CPU clock X2 is set; when X2 is low, this bit has no effect) Cleared to select 6 clock periods per peripheral clock cycle. Set to select 12 clock periods per peripheral clock cycle. 5 PCAX2 4 SIX2 3 T2X2 2 T1X2 1 T0X2 0 X2 7 TWIX2 Watchdog Clock 6 WDX2 (This control bit is validated when the CPU clock X2 is set; when X2 is low, this bit has no effect). Cleared to select 6 clock periods per peripheral clock cycle. Set to select 12 clock periods per peripheral clock cycle. Programmable Counter Array Clock 5 PCAX2 (This control bit is validated when the CPU clock X2 is set; when X2 is low, this bit has no effect). Cleared to select 6 clock periods per peripheral clock cycle. Set to select 12 clock periods per peripheral clock cycle. Enhanced UART Clock (Mode 0 and 2) 4 SIX2 (This control bit is validated when the CPU clock X2 is set; when X2 is low, this bit has no effect). Cleared to select 6 clock periods per peripheral clock cycle. Set to select 12 clock periods per peripheral clock cycle. Timer2 Clock 3 T2X2 (This control bit is validated when the CPU clock X2 is set; when X2 is low, this bit has no effect). Cleared to select 6 clock periods per peripheral clock cycle. Set to select 12 clock periods per peripheral clock cycle. Timer1 Clock 2 T1X2 (This control bit is validated when the CPU clock X2 is set; when X2 is low, this bit has no effect). Cleared to select 6 clock periods per peripheral clock cycle. Set to select 12 clock periods per peripheral clock cycle. Timer0 Clock 1 T0X2 (This control bit is validated when the CPU clock X2 is set; when X2 is low, this bit has no effect). Cleared to select 6 clock periods per peripheral clock cycle. Set to select 12 clock periods per peripheral clock cycle. CPU Clock 0 X2 Cleared to select 12 clock periods per machine cycle (STD mode) for CPU and all the peripherals. Set to select 6clock periods per machine cycle (X2 mode) and to enable the individual peripherals’X2’ bits. Programmed by hardware after Power-up regarding Hardware Security Byte (HSB), Default setting, X2 is cleared. Reset Value = 0000 000’HSB. X2’b (See “Hardware Security Byte”) Not bit addressable 24 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Table 21. CKCON1 Register CKCON1 - Clock Control Register (AFh) 7 Bit Number 7 6 5 4 3 2 1 6 Bit Mnemonic Description Reserved Reserved Reserved Reserved Reserved Reserved Reserved SPI (This control bit is validated when the CPU clock X2 is set; when X2 is low, this bit has no effect). Clear to select 6 clock periods per peripheral clock cycle. Set to select 12 clock periods per peripheral clock cycle. 5 4 3 2 1 0 SPIX2 0 SPIX2 Reset Value = XXXX XXX0b Not bit addressable 25 4289A–8051–09/03 Dual Data Pointer Register DPTR The additional data pointer can be used to speed up code execution and reduce code size. The dual DPTR structure is a way by which the chip will specify the address of an external data memory location. There are two 16-bit DPTR registers that address the external memory, and a single bit called DPS = AUXR1.0 (see Table 22) that allows the program code to switch between them (Refer to Figure 6). Figure 6. Use of Dual Pointer External Data Memory 7 0 DPS DPTR1 DPTR0 AUXR1(A2H) DPH(83H) DPL(82H) 26 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Table 22. AUXR1 register AUXR1- Auxiliary Register 1(0A2h) 7 Bit Number 7 6 Bit Mnemonic Description Reserved The value read from this bit is indeterminate. Do not set this bit. Reserved The value read from this bit is indeterminate. Do not set this bit. Enable Boot Flash Cleared to disable boot ROM. Set to map the boot ROM between F800h - 0FFFFh. 4 3 2 1 GF3 0 Reserved The value read from this bit is indeterminate. Do not set this bit. This bit is a general purpose user flag. * Always cleared. Reserved The value read from this bit is indeterminate. Do not set this bit. Data Pointer Selection Cleared to select DPTR0. Set to select DPTR1. 5 ENBOOT 4 3 GF3 2 0 1 0 DPS 6 - 5 ENBOOT 0 DPS Reset Value: XXXX XX0X0b Not bit addressable Note: *Bit 2 stuck at 0; this allows to use INC AUXR1 to toggle DPS without changing GF3. ASSEMBLY LANGUAGE ; Block move using dual data pointers ; Modifies DPTR0, DPTR1, A and PSW ; note: DPS exits opposite of entry state ; unless an extra INC AUXR1 is added ; 00A2 AUXR1 EQU 0A2H ; 0000 909000MOV DPTR,#SOURCE ; address of SOURCE 0003 05A2 INC AUXR1 ; switch data pointers 0005 90A000 MOV DPTR,#DEST ; address of DEST 0008 LOOP: 0008 05A2 INC AUXR1 ; switch data pointers 000A E0 MOVX A,@DPTR ; get a byte from SOURCE 000B A3 INC DPTR ; increment SOURCE address 000C 05A2 INC AUXR1 ; switch data pointers 000E F0 MOVX @DPTR,A ; write the byte to DEST 000F A3 INC DPTR ; increment DEST address 0010 70F6JNZ LOOP ; check for 0 terminator 0012 05A2 INC AUXR1 ; (optional) restore DPS 27 4289A–8051–09/03 INC is a short (2 bytes) and fast (12 clocks) way to manipulate the DPS bit in the AUXR1 SFR. However, note that the INC instruction does not directly force the DPS bit to a particular state, but simply toggles it. In simple routines, such as the block move example, only the fact that DPS is toggled in the proper sequence matters, not its actual value. In other words, the block move routine works the same whether DPS is ’0’ or ’1’ on entry. Observe that without the last instruction (INC AUXR1), the routine will exit with DPS in the opposite state. 28 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Expanded RAM (XRAM) The AT89C51ID2 provides additional Bytes of random access memory (RAM) space for increased data parameter handling and high level language usage. AT89C51ID2 devices have expanded RAM in external data space configurable up to 1792bytes (see Table 23.). The AT89C51ID2 has internal data memory that is mapped into four separate segments. The four segments are: 1. The Lower 128 bytes of RAM (addresses 00h to 7Fh) are directly and indirectly addressable. 2. The Upper 128 bytes of RAM (addresses 80h to FFh) are indirectly addressable only. 3. The Special Function Registers, SFRs, (addresses 80h to FFh) are directly addressable only. 4. The expanded RAM bytes are indirectly accessed by MOVX instructions, and with the EXTRAM bit cleared in the AUXR register (see Table 23). The lower 128 bytes can be accessed by either direct or indirect addressing. The Upper 128 bytes can be accessed by indirect addressing only. The Upper 128 bytes occupy the same address space as the SFR. That means they have the same address, but are physically separate from SFR space. Figure 7. Internal and External Data Memory Address 0FFh to 6FFh 0FFh Upper 128 bytes Internal Ram indirect accesses XRAM 80h 7Fh Lower 128 bytes Internal Ram direct or indirect accesses 00 00 80h 0FFh 0FFFFh Special Function Register direct accesses External Data Memory 00FFh up to 06FFh 0000 When an instruction accesses an internal location above address 7Fh, the CPU knows whether the access is to the upper 128 bytes of data RAM or to SFR space by the addressing mode used in the instruction. • • Instructions that use direct addressing access SFR space. For example: MOV 0A0H, # data, accesses the SFR at location 0A0h (which is P2). Instructions that use indirect addressing access the Upper 128 bytes of data RAM. For example: MOV @R0, # data where R0 contains 0A0h, accesses the data byte at address 0A0h, rather than P2 (whose address is 0A0h). The XRAM bytes can be accessed by indirect addressing, with EXTRAM bit cleared and MOVX instructions. This part of memory which is physically located on-chip, logically occupies the first bytes of external data memory. The bits XRS0 and XRS1 are used to hide a part of the available XRAM as explained in Table 23. This can be • 29 4289A–8051–09/03 useful if external peripherals are mapped at addresses already used by the internal XRAM. • With EXTRAM = 0, the XRAM is indirectly addressed, using the MOVX instruction in combination with any of the registers R0, R1 of the selected bank or DPTR. An access to XRAM will not affect ports P0, P2, P3.6 (WR) and P3.7 (RD). For example, with EXTRAM = 0, MOVX @R0, # data where R0 contains 0A0H, accesses the XRAM at address 0A0H rather than external memory. An access to external data memory locations higher than the accessible size of the XRAM will be performed with the MOVX DPTR instructions in the same way as in the standard 80C51, with P0 and P2 as data/address busses, and P3.6 and P3.7 as write and read timing signals. Accesses to XRAM above 0FFH can only be done by the use of DPTR. With EXTRAM = 1, MOVX @Ri and MOVX @DPTR will be similar to the standard 80C51.MOVX @ Ri will provide an eight-bit address multiplexed with data on Port0 and any output port pins can be used to output higher order address bits. This is to provide the external paging capability. MOVX @DPTR will generate a sixteen-bit address. Port2 outputs the high-order eight address bits (the contents of DPH) while Port0 multiplexes the low-order eight address bits (DPL) with data. MOVX @ Ri and MOVX @DPTR will generate either read or write signals on P3.6 (WR) and P3.7 (RD). • The stack pointer (SP) may be located anywhere in the 256 bytes RAM (lower and upper RAM) internal data memory. The stack may not be located in the XRAM. The M0 bit allows to stretch the XRAM timings; if M0 is set, the read and write pulses are extended from 6 to 30 clock periods. This is useful to access external slow peripherals. 30 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Registers Table 23. AUXR Register AUXR - Auxiliary Register (8Eh) 7 6 5 M0 4 XRS2 3 XRS1 2 XRS0 1 EXTRAM 0 AO Bit Number 7 Bit Mnemonic Description Reserved The value read from this bit is indeterminate. Do not set this bit. Reserved The value read from this bit is indeterminate. Do not set this bit. Pulse length 6 - 5 M0 Cleared to stretch MOVX control: the RD/ and the WR/ pulse length is 6 clock periods (default). Set to stretch MOVX control: the RD/ and the WR/ pulse length is 30 clock periods. 4 3 XRS2 XRS1 XRAM Size XRS2XRS1XRS0XRAM size 0 0 0256 bytes 0 0 1 1 0 1512 bytes 0768 bytes(default) 11024 bytes 01792 bytes 0 0 1 2 XRS0 EXTRAM bit Cleared to access internal XRAM using movx @ Ri/ @ DPTR. 1 EXTRAM Set to access external memory. Programmed by hardware after Power-up regarding Hardware Security Byte (HSB), default setting, XRAM selected. ALE Output bit Cleared, ALE is emitted at a constant rate of 1/6 the oscillator frequency (or 1/3 if X2 mode is used). (default) Set, ALE is active only during a MOVX or MOVC instruction is used. 0 AO Reset Value = XX00 10’HSB. XRAM’0b Not bit addressable 31 4289A–8051–09/03 Reset Introduction The reset sources are : Power Management, Hardware Watchdog, PCA Watchdog and Reset input. Figure 8. Reset schematic Power Monitor Hardware Watchdog PCA Watchdog Internal Reset RST Reset Input The Reset input can be used to force a reset pulse longer than the internal reset controlled by the Power Monitor. RST input has a pull-down resistor allowing power-on reset by simply connecting an external capacitor to VCC as shown in Figure 9. Resistor value and input characteristics are discussed in the Section “DC Characteristics” of the AT89C51ID2 datasheet. Figure 9. Reset Circuitry and Power-On Reset VDD RST R To internal reset + RST RST VSS a. RST input circuitry b. Power-on Reset 32 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Reset Output As detailed in Section “Hardware Watchdog Timer”, page 108, the WDT generates a 96clock period pulse on the RST pin. In order to properly propagate this pulse to the rest of the application in case of external capacitor or power-supply supervisor circuit, a 1 kΩ resistor must be added as shown Figure 10. Figure 10. Recommended Reset Output Schematic VDD + RST VDD 1K AT89C51ID2 RST VSS To other on-board circuitry 33 4289A–8051–09/03 Power Monitor The POR/PFD function monitors the internal power-supply of the CPU core memories and the peripherals, and if needed, suspends their activity when the internal power supply falls below a safety threshold. This is achieved by applying an internal reset to them. By generating the Reset the Power Monitor insures a correct start up when AT89C51ID2 is powered up. Description In order to startup and maintain the microcontroller in correct operating mode, VCC has to be stabilized in the VCC operating range and the oscillator has to be stabilized with a nominal amplitude compatible with logic level VIH/VIL. These parameters are controlled during the three phases: power-up, normal operation and power going down. See Figure 11. Figure 11. Power Monitor Block Diagram VCC CPU core Power On Reset Power Fail Detect Voltage Regulator Regulated Supply Memories Peripherals XTAL1 (1) Internal Reset RST pin PCA Watchdog Hardware Watchdog Note: 1. Once XTAL1 High and low levels reach above and below VIH/VIL. a 1024 clock period delay will extend the reset coming from the Power Fail Detect. If the power falls below the Power Fail Detect threshold level, the Reset will be applied immediately. The Voltage regulator generates a regulated internal supply for the CPU core the memories and the peripherals. Spikes on the external Vcc are smoothed by the voltage regulator. 34 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 The Power fail detect monitor the supply generated by the voltage regulator and generate a reset if this supply falls below a safety threshold as illustrated in the Figure 12 below. Figure 12. Power Fail Detect Vcc t Reset Vcc When the power is applied, the Power Monitor immediately asserts a reset. Once the internal supply after the voltage regulator reach a safety level, the power monitor then looks at the XTAL clock input. The internal reset will remain asserted until the Xtal1 levels are above and below VIH and VIL. Further more. An internal counter will count 1024 clock periods before the reset is de-asserted. If the internal power supply falls below a safety level, a reset is immediately asserted. 35 4289A–8051–09/03 Timer 2 The Timer 2 in the AT89C51ID2 is the standard C52 Timer 2. It is a 16-bit timer/counter: the count is maintained by two eight-bit timer registers, TH2 and TL2 are cascaded. It is controlled by T2CON (Table 24) and T2MOD (Table 25) registers. Timer 2 operation is similar to Timer 0 and Timer 1.C/T2 selects FOSC/12 (timer operation) or external pin T2 (counter operation) as the timer clock input. Setting TR2 allows TL2 to increment by the selected input. Timer 2 has 3 operating modes: capture, autoreload and Baud Rate Generator. These modes are selected by the combination of RCLK, TCLK and CP/RL2 (T2CON). Refer to the Atmel 8-bit Microcontroller Hardware description for the description of Capture and Baud Rate Generator Modes. Timer 2 includes the following enhancements: • • Auto-reload mode with up or down counter Programmable clock-output Auto-Reload Mode The auto-reload mode configures Timer 2 as a 16-bit timer or event counter with automatic reload. If DCEN bit in T2MOD is cleared, Timer 2 behaves as in 80C52 (refer to the Atmel C51 Microcontroller Hardware description). If DCEN bit is set, Timer 2 acts as an Up/down timer/counter as shown in Figure 13. In this mode the T2EX pin controls the direction of count. When T2EX is high, Timer 2 counts up. Timer overflow occurs at FFFFh which sets the TF2 flag and generates an interrupt request. The overflow also causes the 16-bit value in RCAP2H and RCAP2L registers to be loaded into the timer registers TH2 and TL2. When T2EX is low, Timer 2 counts down. Timer underflow occurs when the count in the timer registers TH2 and TL2 equals the value stored in RCAP2H and RCAP2L registers. The underflow sets TF2 flag and reloads FFFFh into the timer registers. The EXF2 bit toggles when Timer 2 overflows or underflows according to the direction of the count. EXF2 does not generate any interrupt. This bit can be used to provide 17-bit resolution. 36 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Figure 13. Auto-Reload Mode Up/Down Counter (DCEN = 1) FCLK PERIPH :6 T2 0 1 C/T2 T2CON TR2 T2CON T2EX: (DOWN COUNTING RELOAD VALUE) if DCEN=1, 1=UP FFh FFh if DCEN=1, 0=DOWN (8-bit) (8-bit) if DCEN = 0, up counting TOGGLE T2CON EXF2 TL2 (8-bit) TH2 (8-bit) TF2 T2CON TIMER 2 INTERRUPT RCAP2L (8-bit) RCAP2H (8-bit) (UP COUNTING RELOAD VALUE) Programmable ClockOutput In the clock-out mode, Timer 2 operates as a 50%-duty-cycle, programmable clock generator (See Figure 14). The input clock increments TL2 at frequency FCLK PERIPH/2.The timer repeatedly counts to overflow from a loaded value. At overflow, the contents of RCAP2H and RCAP2L registers are loaded into TH2 and TL2.In this mode, Timer 2 overflows do not generate interrupts. The formula gives the clock-out frequency as a function of the system oscillator frequency and the value in the RCAP2H and RCAP2L registers: F CLKPERIPH C lock – O utFrequency = -------------------------------------------------------------------------------------------4 × ( 65536 – RCAP 2 H ⁄ RCAP 2 L ) For a 16 MHz system clock, Timer 2 has a programmable frequency range of 61 Hz (FCLK PERIPH/216) to 4 MHz (FCLK PERIPH/4). The generated clock signal is brought out to T2 pin (P1.0). Timer 2 is programmed for the clock-out mode as follows: • • • • • Set T2OE bit in T2MOD register. Clear C/T2 bit in T2CON register. Determine the 16-bit reload value from the formula and enter it in RCAP2H/RCAP2L registers. Enter a 16-bit initial value in timer registers TH2/TL2.It can be the same as the reload value or a different one depending on the application. To start the timer, set TR2 run control bit in T2CON register. It is possible to use Timer 2 as a baud rate generator and a clock generator simultaneously. For this configuration, the baud rates and clock frequencies are not independent since both functions use the values in the RCAP2H and RCAP2L registers. 37 4289A–8051–09/03 Figure 14. Clock-Out Mode C/T2 = 0 FCLK PERIPH :6 TR2 T2CON TL2 (8-bit) TH2 (8-bit) OVERFLOW RCAP2L RCAP2H (8-bit) (8-bit) Toggle T2 Q D T2OE T2MOD T2EX EXEN2 T2CON EXF2 T2CON TIMER 2 INTERRUPT 38 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Registers Table 24. T2CON Register T2CON - Timer 2 Control Register (C8h) 7 TF2 Bit Number 6 EXF2 Bit Mnemonic Description Timer 2 overflow Flag Must be cleared by software. Set by hardware on Timer 2 overflow, if RCLK = 0 and TCLK = 0. Timer 2 External Flag Set when a capture or a reload is caused by a negative transition on T2EX pin if EXEN2=1. When set, causes the CPU to vector to Timer 2 interrupt routine when Timer 2 interrupt is enabled. Must be cleared by software. EXF2 doesn’t cause an interrupt in Up/down counter mode (DCEN = 1). Receive Clock bit Cleared to use timer 1 overflow as receive clock for serial port in mode 1 or 3. Set to use Timer 2 overflow as receive clock for serial port in mode 1 or 3. Transmit Clock bit Cleared to use timer 1 overflow as transmit clock for serial port in mode 1 or 3. Set to use Timer 2 overflow as transmit clock for serial port in mode 1 or 3. Timer 2 External Enable bit Cleared to ignore events on T2EX pin for Timer 2 operation. Set to cause a capture or reload when a negative transition on T2EX pin is detected, if Timer 2 is not used to clock the serial port. Timer 2 Run control bit Cleared to turn off Timer 2. Set to turn on Timer 2. Timer/Counter 2 select bit Cleared for timer operation (input from internal clock system: FCLK PERIPH). Set for counter operation (input from T2 input pin, falling edge trigger). Must be 0 for clock out mode. Timer 2 Capture/Reload bit If RCLK=1 or TCLK=1, CP/RL2# is ignored and timer is forced to auto-reload on Timer 2 overflow. Cleared to auto-reload on Timer 2 overflows or negative transitions on T2EX pin if EXEN2=1. Set to capture on negative transitions on T2EX pin if EXEN2=1. 5 RCLK 4 TCLK 3 EXEN2 2 TR2 1 C/T2# 0 CP/RL2# 7 TF2 6 EXF2 5 RCLK 4 TCLK 3 EXEN2 2 TR2 1 C/T2# 0 CP/RL2# Reset Value = 0000 0000b Bit addressable 39 4289A–8051–09/03 Table 25. T2MOD Register T2MOD - Timer 2 Mode Control Register (C9h) 7 Bit Number 7 6 Bit Mnemonic Description Reserved The value read from this bit is indeterminate. Do not set this bit. Reserved The value read from this bit is indeterminate. Do not set this bit. Reserved The value read from this bit is indeterminate. Do not set this bit. Reserved The value read from this bit is indeterminate. Do not set this bit. Reserved The value read from this bit is indeterminate. Do not set this bit. Reserved The value read from this bit is indeterminate. Do not set this bit. Timer 2 Output Enable bit Cleared to program P1.0/T2 as clock input or I/O port. Set to program P1.0/T2 as clock output. Down Counter Enable bit Cleared to disable Timer 2 as up/down counter. Set to enable Timer 2 as up/down counter. 5 4 3 2 1 T2OE 0 DCEN 6 - 5 - 4 - 3 - 2 - 1 T2OE 0 DCEN Reset Value = XXXX XX00b Not bit addressable 40 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Programmable Counter Array PCA The PCA provides more timing capabilities with less CPU intervention than the standard timer/counters. Its advantages include reduced software overhead and improved accuracy. The PCA consists of a dedicated timer/counter which serves as the time base for an array of five compare/capture modules. Its clock input can be programmed to count any one of the following signals: • • • • • • • • ÷6 Peripheral clock frequency (FCLK PERIPH) ÷ 2 Peripheral clock frequency (FCLK PERIPH) Timer 0 overflow External input on ECI (P1.2) Rising and/or falling edge capture Software timer High-speed output Pulse width modulator Each compare/capture modules can be programmed in any one of the following modes: Module 4 can also be programmed as a watchdog timer (See Section "PCA Watchdog Timer", page 52). When the compare/capture modules are programmed in the capture mode, software timer, or high speed output mode, an interrupt can be generated when the module executes its function. All five modules plus the PCA timer overflow share one interrupt vector. The PCA timer/counter and compare/capture modules share Port 1 for external I/O. These pins are listed below. If the port is not used for the PCA, it can still be used for standard I/O. PCA component 16-bit Counter 16-bit Module 0 16-bit Module 1 16-bit Module 2 16-bit Module 3 External I/O Pin P1.2 / ECI P1.3 / CEX0 P1.4 / CEX1 P1.5 / CEX2 P1.6 / CEX3 The PCA timer is a common time base for all five modules (See Figure 15). The timer count source is determined from the CPS1 and CPS0 bits in the CMOD register (Table 26) and can be programmed to run at: • • • • 1/6 the peripheral clock frequency (FCLK PERIPH) 1/2 the peripheral clock frequency (FCLK PERIPH) The Timer 0 overflow The input on the ECI pin (P1.2) 41 4289A–8051–09/03 Figure 15. PCA Timer/Counter To PCA modules Fclk periph /6 Fclk periph / 2 T0 OVF P1.2 CH CL 16 bit up/down counter overflow It CIDL Idle WDTE CPS1 CPS0 ECF CMOD 0xD9 CF CR CCF4 CCF3 CCF2 CCF1 CCF0 CCON 0xD8 42 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Table 26. CMOD Register CMOD - PCA Counter Mode Register (D9h) 7 CIDL Bit Number 6 WDTE Bit Mnemonic Description Counter Idle Control 7 CIDL Cleared to program the PCA Counter to continue functioning during idle Mode. Set to program PCA to be gated off during idle. Watchdog Timer Enable 6 WDTE Cleared to disable Watchdog Timer function on PCA Module 4. Set to enable Watchdog Timer function on PCA Module 4. 5 Reserved The value read from this bit is indeterminate. Do not set this bit. Reserved The value read from this bit is indeterminate. Do not set this bit. Reserved The value read from this bit is indeterminate. Do not set this bit. PCA Count Pulse Select CPS1 0 1 CPS0 0 1 1 CPS0Selected PCA input 0 Internal clock fCLK PERIPH/6 1Internal clock fCLK PERIPH/2 0Timer 0 Overflow 1 External clock at ECI/P1.2 pin (max rate = fCLK PERIPH/ 4) 5 4 3 2 CPS1 1 CPS0 0 ECF 4 - 3 2 CPS1 0 ECF PCA Enable Counter Overflow Interrupt Cleared to disable CF bit in CCON to inhibit an interrupt. Set to enable CF bit in CCON to generate an interrupt. Reset Value = 00XX X000b Not bit addressable The CMOD register includes three additional bits associated with the PCA (See Figure 15 and Table 26). • • • The CIDL bit which allows the PCA to stop during idle mode. The WDTE bit which enables or disables the watchdog function on module 4. The ECF bit which when set causes an interrupt and the PCA overflow flag CF (in the CCON SFR) to be set when the PCA timer overflows. The CCON register contains the run control bit for the PCA and the flags for the PCA timer (CF) and each module (Refer to Table 27). • • Bit CR (CCON.6) must be set by software to run the PCA. The PCA is shut off by clearing this bit. Bit CF: The CF bit (CCON.7) is set when the PCA counter overflows and an interrupt will be generated if the ECF bit in the CMOD register is set. The CF bit can only be cleared by software. 43 4289A–8051–09/03 • Bits 0 through 4 are the flags for the modules (bit 0 for module 0, bit 1 for module 1, etc.) and are set by hardware when either a match or a capture occurs. These flags also can only be cleared by software. Table 27. CCON Register CCON - PCA Counter Control Register (D8h) 7 CF Bit Number 6 CR Bit Mnemonic Description PCA Counter Overflow flag 7 CF Set by hardware when the counter rolls over. CF flags an interrupt if bit ECF in CMOD is set. CF may be set by either hardware or software but can only be cleared by software. PCA Counter Run control bit 6 CR Must be cleared by software to turn the PCA counter off. Set by software to turn the PCA counter on. 5 Reserved The value read from this bit is indeterminate. Do not set this bit. PCA Module 4 interrupt flag 4 CCF4 Must be cleared by software. Set by hardware when a match or capture occurs. PCA Module 3 interrupt flag 3 CCF3 Must be cleared by software. Set by hardware when a match or capture occurs. PCA Module 2 interrupt flag 2 CCF2 Must be cleared by software. Set by hardware when a match or capture occurs. PCA Module 1 interrupt flag 1 CCF1 Must be cleared by software. Set by hardware when a match or capture occurs. PCA Module 0 interrupt flag 0 CCF0 Must be cleared by software. Set by hardware when a match or capture occurs. 5 4 CCF4 3 CCF3 2 CCF2 1 CCF1 0 CCF0 Reset Value = 00X0 0000b Not bit addressable The watchdog timer function is implemented in module 4 (See Figure 18). The PCA interrupt system is shown in Figure 16. 44 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Figure 16. PCA Interrupt System CF PCA Timer/Counter CR CCF4 CCF3 CCF2 CCF1 CCF0 CCON 0xD8 Module 0 Module 1 To Interrupt priority decoder Module 2 Module 3 Module 4 CMOD.0 ECF ECCFn CCAPMn.0 IE.6 EC IE.7 EA PCA Modules: each one of the five compare/capture modules has six possible functions. It can perform: • • • • • • 16-bit Capture, positive-edge triggered 16-bit Capture, negative-edge triggered 16-bit Capture, both positive and negative-edge triggered 16-bit Software Timer 16-bit High Speed Output 8-bit Pulse Width Modulator In addition, module 4 can be used as a Watchdog Timer. Each module in the PCA has a special function register associated with it. These registers are: CCAPM0 for module 0, CCAPM1 for module 1, etc. (See Table 28). The registers contain the bits that control the mode that each module will operate in. • The ECCF bit (CCAPMn.0 where n=0, 1, 2, 3, or 4 depending on the module) enables the CCF flag in the CCON SFR to generate an interrupt when a match or compare occurs in the associated module. PWM (CCAPMn.1) enables the pulse width modulation mode. The TOG bit (CCAPMn.2) when set causes the CEX output associated with the module to toggle when there is a match between the PCA counter and the module's capture/compare register. The match bit MAT (CCAPMn.3) when set will cause the CCFn bit in the CCON register to be set when there is a match between the PCA counter and the module's capture/compare register. The next two bits CAPN (CCAPMn.4) and CAPP (CCAPMn.5) determine the edge that a capture input will be active on. The CAPN bit enables the negative edge, and the CAPP bit enables the positive edge. If both bits are set both edges will be enabled and a capture will occur for either transition. The last bit in the register ECOM (CCAPMn.6) when set enables the comparator function. • • • • • 45 4289A–8051–09/03 Table 28 shows the CCAPMn settings for the various PCA functions. Table 28. CCAPMn Registers (n = 0-4) CCAPM0 - PCA Module 0 Compare/Capture Control Register (0DAh) CCAPM1 - PCA Module 1 Compare/Capture Control Register (0DBh) CCAPM2 - PCA Module 2 Compare/Capture Control Register (0DCh) CCAPM3 - PCA Module 3 Compare/Capture Control Register (0DDh) CCAPM4 - PCA Module 4 Compare/Capture Control Register (0DEh) 7 Bit Number 7 6 ECOMn Bit Mnemonic Description Reserved The value read from this bit is indeterminate. Do not set this bit. Enable Comparator 6 ECOMn Cleared to disable the comparator function. Set to enable the comparator function. Capture Positive 5 CAPPn Cleared to disable positive edge capture. Set to enable positive edge capture. Capture Negative 4 CAPNn Cleared to disable negative edge capture. Set to enable negative edge capture. Match 3 MATn When MATn = 1, a match of the PCA counter with this module’s compare/capture register causes the CCFn bit in CCON to be set, flagging an interrupt. Toggle 2 TOGn When TOGn = 1, a match of the PCA counter with this module’s compare/capture register causes the CEXn pin to toggle. Pulse Width Modulation Mode 1 PWMn Cleared to disable the CEXn pin to be used as a pulse width modulated output. Set to enable the CEXn pin to be used as a pulse width modulated output. Enable CCF interrupt 0 CCF0 Cleared to disable compare/capture flag CCFn in the CCON register to generate an interrupt. Set to enable compare/capture flag CCFn in the CCON register to generate an interrupt. 5 CAPPn 4 CAPNn 3 MATn 2 TOGn 1 PWMn 0 ECCFn Reset Value = X000 0000b Not bit addressable 46 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Table 29. PCA Module Modes (CCAPMn Registers) ECOMn 0 X CAPPn 0 1 CAPNn 0 0 MATn 0 0 TOGn 0 0 PWMm 0 0 ECCFn 0 X Module Function No Operation 16-bit capture by a positive-edge trigger on CEXn 16-bit capture by a negative trigger on CEXn 16-bit capture by a transition on CEXn 16-bit Software Timer / Compare mode. 16-bit High Speed Output 8-bit PWM Watchdog Timer (module 4 only) X 0 1 0 0 0 X X 1 1 0 0 0 X 1 1 1 1 0 0 0 0 0 0 0 0 1 1 0 1 0 1 0 X 0 0 1 0 X X 0 X There are two additional registers associated with each of the PCA modules. They are CCAPnH and CCAPnL and these are the registers that store the 16-bit count when a capture occurs or a compare should occur. When a module is used in the PWM mode these registers are used to control the duty cycle of the output (See Table 30 & Table 31). Table 30. CCAPnH Registers (n = 0-4) CCAP0H - PCA Module 0 Compare/Capture Control Register High (0FAh) CCAP1H - PCA Module 1 Compare/Capture Control Register High (0FBh) CCAP2H - PCA Module 2 Compare/Capture Control Register High (0FCh) CCAP3H - PCA Module 3 Compare/Capture Control Register High (0FDh) CCAP4H - PCA Module 4 Compare/Capture Control Register High (0FEh) 7 Bit Number 7-0 6 Bit Mnemonic Description PCA Module n Compare/Capture Control CCAPnH Value 5 4 3 2 1 0 - Reset Value = 0000 0000b Not bit addressable 47 4289A–8051–09/03 Table 31. CCAPnL Registers (n = 0-4) CCAP0L - PCA Module 0 Compare/Capture Control Register Low (0EAh) CCAP1L - PCA Module 1 Compare/Capture Control Register Low (0EBh) CCAP2L - PCA Module 2 Compare/Capture Control Register Low (0ECh) CCAP3L - PCA Module 3 Compare/Capture Control Register Low (0EDh) CCAP4L - PCA Module 4 Compare/Capture Control Register Low (0EEh) 7 Bit Number 7-0 6 Bit Mnemonic Description PCA Module n Compare/Capture Control CCAPnL Value 5 4 3 2 1 0 - Reset Value = 0000 0000b Not bit addressable Table 32. CH Register CH - PCA Counter Register High (0F9h) 7 Bit Number 7-0 6 Bit Mnemonic Description PCA counter CH Value 5 4 3 2 1 0 - Reset Value = 0000 0000b Not bit addressable Table 33. CL Register CL - PCA Counter Register Low (0E9h) 7 Bit Number 7-0 6 Bit Mnemonic Description PCA Counter CL Value 5 4 3 2 1 0 - Reset Value = 0000 0000b Not bit addressable 48 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 PCA Capture Mode To use one of the PCA modules in the capture mode either one or both of the CCAPM bits CAPN and CAPP for that module must be set. The external CEX input for the module (on port 1) is sampled for a transition. When a valid transition occurs the PCA hardware loads the value of the PCA counter registers (CH and CL) into the module’s capture registers (CCAPnL and CCAPnH). If the CCFn bit for the module in the CCON SFR and the ECCFn bit in the CCAPMn SFR are set then an interrupt will be generated (Refer to Figure 17). Figure 17. PCA Capture Mode CF CR CCF4 CCF3 CCF2 CCF1 CCF0 CCON 0xD8 PCA IT PCA Counter/Timer Cex.n Capture CH CL CCAPnH CCAPnL ECOMn CAPPn CAPNn MATn TOGn PWMn ECCFn CCAPMn, n= 0 to 4 0xDA to 0xDE 16-bit Software Timer/ Compare Mode The PCA modules can be used as software timers by setting both the ECOM and MAT bits in the modules CCAPMn register. The PCA timer will be compared to the module’s capture registers and when a match occurs an interrupt will occur if the CCFn (CCON SFR) and the ECCFn (CCAPMn SFR) bits for the module are both set (See Figure 18). 49 4289A–8051–09/03 Figure 18. PCA Compare Mode and PCA Watchdog Timer CCON CF Write to CCAPnL Write to CCAPnH 1 0 Enable 16 bit comparator RESET * Reset PCA IT CCAPnH CCAPnL Match CR CCF4 CCF3 CCF2 CCF1 CCF0 0xD8 CH CL PCA counter/timer ECOMn CAPPn CAPNn MATn TOGn PWMn ECCFn CCAPMn, n = 0 to 4 0xDA to 0xDE CIDL WDTE CPS1 CPS0 ECF CMOD 0xD9 Before enabling ECOM bit, CCAPnL and CCAPnH should be set with a non zero value, otherwise an unwanted match could happen. Writing to CCAPnH will set the ECOM bit. Once ECOM set, writing CCAPnL will clear ECOM so that an unwanted match doesn’t occur while modifying the compare value. Writing to CCAPnH will set ECOM. For this reason, user software should write CCAPnL first, and then CCAPnH. Of course, the ECOM bit can still be controlled by accessing to CCAPMn register. High Speed Output Mode In this mode the CEX output (on port 1) associated with the PCA module will toggle each time a match occurs between the PCA counter and the module's capture registers. To activate this mode the TOG, MAT, and ECOM bits in the module's CCAPMn SFR must be set (See Figure 19). A prior write must be done to CCAPnL and CCAPnH before writing the ECOMn bit. 50 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Figure 19. PCA High Speed Output Mode CCON CF CR CCF4 CCF3 CCF2 CCF1 CCF0 0xD8 Write to CCA PnL Reset PCA IT Write to CCAPnH 0 CCAPnH Enable 16 bit comparator CCAPnL Match 1 CH CL CEXn PCA counter/timer CCAPMn, n = 0 to 4 0xDA to 0xDE ECO Mn CAPPn CAPNn MATn TOGn PWMn ECCFn Before enabling ECOM bit, CCAPnL and CCAPnH should be set with a non zero value, otherwise an unwanted match could happen. Once ECOM set, writing CCAPnL will clear ECOM so that an unwanted match doesn’t occur while modifying the compare value. Writing to CCAPnH will set ECOM. For this reason, user software should write CCAPnL first, and then CCAPnH. Of course, the ECOM bit can still be controlled by accessing to CCAPMn register. Pulse Width Modulator Mode All of the PCA modules can be used as PWM outputs. Figure 20 shows the PWM function. The frequency of the output depends on the source for the PCA timer. All of the modules will have the same frequency of output because they all share the PCA timer. The duty cycle of each module is independently variable using the module's capture register CCAPLn. When the value of the PCA CL SFR is less than the value in the module's CCAPLn SFR the output will be low, when it is equal to or greater than the output will be high. When CL overflows from FF to 00, CCAPLn is reloaded with the value in CCAPHn. This allows updating the PWM without glitches. The PWM and ECOM bits in the module's CCAPMn register must be set to enable the PWM mode. 51 4289A–8051–09/03 Figure 20. PCA PWM Mode CCAPnH Overflow CCAPnL “0” Enable 8 bit comparator “1” CL PCA counter/timer CEXn ECOMn CAPPn CAPNn MATn TOGn PWMn ECCFn CCAPMn, n= 0 to 4 0xDA to 0xDE PCA Watchdog Timer An on-board watchdog timer is available with the PCA to improve the reliability of the system without increasing chip count. Watchdog timers are useful for systems that are susceptible to noise, power glitches, or electrostatic discharge. Module 4 is the only PCA module that can be programmed as a watchdog. However, this module can still be used for other modes if the watchdog is not needed. Figure 18 shows a diagram of how the watchdog works. The user pre-loads a 16-bit value in the compare registers. Just like the other compare modes, this 16-bit value is compared to the PCA timer value. If a match is allowed to occur, an internal reset will be generated. This will not cause the RST pin to be driven high. In order to hold off the reset, the user has three options: 1. periodically change the compare value so it will never match the PCA timer, 2. periodically change the PCA timer value so it will never match the compare values, or 3. disable the watchdog by clearing the WDTE bit before a match occurs and then reenable it. The first two options are more reliable because the watchdog timer is never disabled as in option #3. If the program counter ever goes astray, a match will eventually occur and cause an internal reset. The second option is also not recommended if other PCA modules are being used. Remember, the PCA timer is the time base for all modules; changing the time base for other modules would not be a good idea. Thus, in most applications the first solution is the best option. This watchdog timer won’t generate a reset out on the reset pin. 52 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Serial I/O Port The serial I/O port in the AT89C51ID2 is compatible with the serial I/O port in the 80C52. It provides both synchronous and asynchronous communication modes. It operates as a Universal Asynchronous Receiver and Transmitter (UART) in three full-duplex modes (Modes 1, 2 and 3). Asynchronous transmission and reception can occur simultaneously and at different baud rates Serial I/O port includes the following enhancements: • • Framing error detection Automatic address recognition Framing Error Detection Framing bit error detection is provided for the three asynchronous modes (modes 1, 2 and 3). To enable the framing bit error detection feature, set SMOD0 bit in PCON register (See Figure 21). Figure 21. Framing Error Block Diagram SM0/FE SM1 SM2 REN TB8 RB8 TI RI SCON (98h) Set FE bit if stop bit is 0 (framing error) (SMOD0 = 1) SM0 to UART mode control (SMOD0 = 0) SMOD1SMOD0 POF GF1 GF0 PD IDL PCON (87h) To UART framing error control When this feature is enabled, the receiver checks each incoming data frame for a valid stop bit. An invalid stop bit may result from noise on the serial lines or from simultaneous transmission by two CPUs. If a valid stop bit is not found, the Framing Error bit (FE) in SCON register (See Table 37.) bit is set. Software may examine FE bit after each reception to check for data errors. Once set, only software or a reset can clear FE bit. Subsequently received frames with valid stop bits cannot clear FE bit. When FE feature is enabled, RI rises on stop bit instead of the last data bit (See Figure 22. and Figure 23.). Figure 22. UART Timings in Mode 1 RXD Start bit RI SMOD0=X FE SMOD0=1 D0 D1 D2 D3 D4 D5 D6 D7 Stop bit Data byte 53 4289A–8051–09/03 Figure 23. UART Timings in Modes 2 and 3 RXD Start bit RI SMOD0=0 RI SMOD0=1 FE SMOD0=1 D0 D1 D2 D3 D4 D5 D6 D7 D8 Ninth Stop bit bit Data byte Automatic Address Recognition The automatic address recognition feature is enabled when the multiprocessor communication feature is enabled (SM2 bit in SCON register is set). Implemented in hardware, automatic address recognition enhances the multiprocessor communication feature by allowing the serial port to examine the address of each incoming command frame. Only when the serial port recognizes its own address, the receiver sets RI bit in SCON register to generate an interrupt. This ensures that the CPU is not interrupted by command frames addressed to other devices. If desired, the user may enable the automatic address recognition feature in mode 1.In this configuration, the stop bit takes the place of the ninth data bit. Bit RI is set only when the received command frame address matches the device’s address and is terminated by a valid stop bit. To support automatic address recognition, a device is identified by a given address and a broadcast address. Note: The multiprocessor communication and automatic address recognition features cannot be enabled in mode 0 (i. e. setting SM2 bit in SCON register in mode 0 has no effect). Given Address Each device has an individual address that is specified in SADDR register; the SADEN register is a mask byte that contains don’t-care bits (defined by zeros) to form the device’s given address. The don’t-care bits provide the flexibility to address one or more slaves at a time. The following example illustrates how a given address is formed. To address a device by its individual address, the SADEN mask byte must be 1111 1111b. For example: SADDR0101 0110b SADEN1111 1100b Given0101 01XXb The following is an example of how to use given addresses to address different slaves: Slave A:SADDR1111 0001b SADEN1111 1010b Given1111 0X0Xb Slave B:SADDR1111 0011b SADEN1111 1001b Given1111 0XX1b Slave C:SADDR1111 0010b SADEN1111 1101b Given1111 00X1b 54 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 The SADEN byte is selected so that each slave may be addressed separately. For slave A, bit 0 (the LSB) is a don’t-care bit; for slaves B and C, bit 0 is a 1.To communicate with slave A only, the master must send an address where bit 0 is clear (e. g. 1111 0000b). For slave A, bit 1 is a 1; for slaves B and C, bit 1 is a don’t care bit. To communicate with slaves B and C, but not slave A, the master must send an address with bits 0 and 1 both set (e. g. 1111 0011b). To communicate with slaves A, B and C, the master must send an address with bit 0 set, bit 1 clear, and bit 2 clear (e. g. 1111 0001b). Broadcast Address A broadcast address is formed from the logical OR of the SADDR and SADEN registers with zeros defined as don’t-care bits, e. g. : SADDR0101 0110b SADEN1111 1100b Broadcast =SADDR OR SADEN1111 111Xb The use of don’t-care bits provides flexibility in defining the broadcast address, however in most applications, a broadcast address is FFh. The following is an example of using broadcast addresses: Slave A:SADDR1111 0001b SADEN1111 1010b Broadcast1111 1X11b, Slave B:SADDR1111 0011b SADEN1111 1001b Broadcast1111 1X11B, Slave C:SADDR=1111 0011b SADEN1111 1101b Broadcast1111 1111b For slaves A and B, bit 2 is a don’t care bit; for slave C, bit 2 is set. To communicate with all of the slaves, the master must send an address FFh. To communicate with slaves A and B, but not slave C, the master can send and address FBh. Reset Addresses On reset, the SADDR and SADEN registers are initialized to 00h, i. e. the given and broadcast addresses are XXXX XXXXb (all don’t-care bits). This ensures that the serial port will reply to any address, and so, that it is backwards compatible with the 80C51 microcontrollers that do not support automatic address recognition. 55 4289A–8051–09/03 Registers Table 34. SADEN Register SADEN - Slave Address Mask Register (B9h) 7 6 5 4 3 2 1 0 Reset Value = 0000 0000b Not bit addressable Table 35. SADDR Register SADDR - Slave Address Register (A9h) 7 6 5 4 3 2 1 0 Reset Value = 0000 0000b Not bit addressable Baud Rate Selection for UART for Mode 1 and 3 The Baud Rate Generator for transmit and receive clocks can be selected separately via the T2CON and BDRCON registers. Figure 24. Baud Rate Selection TIMER1 TIMER2 0 1 RCLK INT_BRG RBCK TIMER_BRG_RX 0 1 / 16 Rx Clock TIMER1 TIMER2 0 1 TCLK TIMER_BRG_TX 0 1 / 16 Tx Clock INT_BRG TBCK 56 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Table 36. Baud Rate Selection Table UART TCLK (T2CON) 0 1 0 1 X X 0 1 X RCLK (T2CON) 0 0 1 1 0 1 X X X TBCK (BDRCON) 0 0 0 0 1 1 0 0 1 RBCK (BDRCON) 0 0 0 0 0 0 1 1 1 Clock Source UART Tx Timer 1 Timer 2 Timer 1 Timer 2 INT_BRG INT_BRG Timer 1 Timer 2 INT_BRG Clock Source UART Rx Timer 1 Timer 1 Timer 2 Timer 2 Timer 1 Timer 2 INT_BRG INT_BRG INT_BRG Internal Baud Rate Generator (BRG) When the internal Baud Rate Generator is used, the Baud Rates are determined by the BRG overflow depending on the BRL reload value, the value of SPD bit (Speed Mode) in BDRCON register and the value of the SMOD1 bit in PCON register. Figure 25. Internal Baud Rate FPER /6 0 1 SPD BRR BRL SMOD1 auto reload counter overflow BRG /2 0 1 INT_BRG • The baud rate for UART is token by formula: 2SMOD1 ⋅ FPER 6(1-SPD) ⋅ 32 ⋅ (256 -BRL) 2SMOD1 ⋅ FPER ⋅ 32 ⋅ Baud_Rate Baud_Rate = BRL = 256 - 6 (1-SPD) 57 4289A–8051–09/03 Table 37. SCON Register SCON - Serial Control Register (98h) 7 FE/SM0 Bit Number 6 SM1 Bit Mnemonic Description Framing Error bit (SMOD0=1) 7 FE Clear to reset the error state, not cleared by a valid stop bit. Set by hardware when an invalid stop bit is detected. SMOD0 must be set to enable access to the FE bit. Serial port Mode bit 0 Refer to SM1 for serial port mode selection. SMOD0 must be cleared to enable access to the SM0 bit. Serial port Mode bit 1 SM0SM1ModeDescriptionBaud Rate 6 SM1 0 0 1 1 0 1 0 1 0Shift RegisterFCPU PERIPH/6 18-bit UARTVariable 29-bit UARTFCPU PERIPH /32 or /16 39-bit UARTVariable 5 SM2 4 REN 3 TB8 2 RB8 1 TI 0 RI SM0 Serial port Mode 2 bit / Multiprocessor Communication Enable bit 5 SM2 Clear to disable multiprocessor communication feature. Set to enable multiprocessor communication feature in mode 2 and 3, and eventually mode 1.This bit should be cleared in mode 0. Reception Enable bit Clear to disable serial reception. Set to enable serial reception. Transmitter Bit 8 / Ninth bit to transmit in modes 2 and 3 3 TB8 Clear to transmit a logic 0 in the 9th bit. Set to transmit a logic 1 in the 9th bit. Receiver Bit 8 / Ninth bit received in modes 2 and 3 Cleared by hardware if 9th bit received is a logic 0. Set by hardware if 9th bit received is a logic 1. In mode 1, if SM2 = 0, RB8 is the received stop bit. In mode 0 RB8 is not used. Transmit Interrupt flag Clear to acknowledge interrupt. Set by hardware at the end of the 8th bit time in mode 0 or at the beginning of the stop bit in the other modes. Receive Interrupt flag Clear to acknowledge interrupt. Set by hardware at the end of the 8th bit time in mode 0, see Figure 22. and Figure 23. in the other modes. 4 REN 2 RB8 1 TI 0 RI Reset Value = 0000 0000b Bit addressable 58 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Table 38. Example of Computed Value When X2=1, SMOD1=1, SPD=1 Baud Rates FOSC = 16. 384 MHz BRL 115200 57600 38400 28800 19200 9600 4800 247 238 229 220 203 149 43 Error (%) 1.23 1.23 1.23 1.23 0.63 0.31 1.23 BRL 243 230 217 204 178 100 FOSC = 24MHz Error (%) 0.16 0.16 0.16 0.16 0.16 0.16 - Table 39. Example of Computed Value When X2=0, SMOD1=0, SPD=0 Baud Rates FOSC = 16. 384 MHz BRL 4800 2400 1200 600 247 238 220 185 Error (%) 1.23 1.23 1.23 0.16 BRL 243 230 202 152 FOSC = 24MHz Error (%) 0.16 0.16 3.55 0.16 The baud rate generator can be used for mode 1 or 3 (refer to Figure 24.), but also for mode 0 for UART, thanks to the bit SRC located in BDRCON register (Table 46.) UART Registers Table 40. SADEN Register SADEN - Slave Address Mask Register for UART (B9h) 7 6 5 4 3 2 1 0 Reset Value = 0000 0000b Table 41. SADDR Register SADDR - Slave Address Register for UART (A9h) 7 6 5 4 3 2 1 0 Reset Value = 0000 0000b 59 4289A–8051–09/03 Table 42. SBUF Register SBUF - Serial Buffer Register for UART (99h) 7 6 5 4 3 2 1 0 Reset Value = XXXX XXXXb Table 43. BRL Register BRL - Baud Rate Reload Register for the internal baud rate generator, UART (9Ah) 7 6 5 4 3 2 1 0 Reset Value = 0000 0000b 60 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Table 44. T2CON Register T2CON - Timer 2 Control Register (C8h) 7 TF2 Bit Number 6 EXF2 Bit Mnemonic Description Timer 2 overflow Flag Must be cleared by software. Set by hardware on timer 2 overflow, if RCLK = 0 and TCLK = 0. Timer 2 External Flag Set when a capture or a reload is caused by a negative transition on T2EX pin if EXEN2=1. When set, causes the CPU to vector to timer 2 interrupt routine when timer 2 interrupt is enabled. Must be cleared by software. EXF2 doesn’t cause an interrupt in Up/down counter mode (DCEN = 1) Receive Clock bit for UART Cleared to use timer 1 overflow as receive clock for serial port in mode 1 or 3. Set to use timer 2 overflow as receive clock for serial port in mode 1 or 3. Transmit Clock bit for UART Cleared to use timer 1 overflow as transmit clock for serial port in mode 1 or 3. Set to use timer 2 overflow as transmit clock for serial port in mode 1 or 3. Timer 2 External Enable bit Cleared to ignore events on T2EX pin for timer 2 operation. Set to cause a capture or reload when a negative transition on T2EX pin is detected, if timer 2 is not used to clock the serial port. Timer 2 Run control bit Cleared to turn off timer 2. Set to turn on timer 2. Timer/Counter 2 select bit Cleared for timer operation (input from internal clock system: FCLK PERIPH). Set for counter operation (input from T2 input pin, falling edge trigger). Must be 0 for clock out mode. Timer 2 Capture/Reload bit If RCLK=1 or TCLK=1, CP/RL2# is ignored and timer is forced to auto-reload on timer 2 overflow. Cleared to auto-reload on timer 2 overflows or negative transitions on T2EX pin if EXEN2=1. Set to capture on negative transitions on T2EX pin if EXEN2=1. 5 RCLK 4 TCLK 3 EXEN2 2 TR2 1 C/T2# 0 CP/RL2# 7 TF2 6 EXF2 5 RCLK 4 TCLK 3 EXEN2 2 TR2 1 C/T2# 0 CP/RL2# Reset Value = 0000 0000b Bit addressable 61 4289A–8051–09/03 Table 45. PCON Register PCON - Power Control Register (87h) 7 SMOD1 Bit Number 7 6 SMOD0 Bit Mnemonic SMOD1 Description Serial port Mode bit 1 for UART Set to select double baud rate in mode 1, 2 or 3. Serial port Mode bit 0 for UART 6 SMOD0 Cleared to select SM0 bit in SCON register. Set to select FE bit in SCON register. Reserved The value read from this bit is indeterminate. Do not set this bit. Power-Off Flag Cleared to recognize next reset type. Set by hardware when VCC rises from 0 to its nominal voltage. Can also be set by software. General purpose Flag Cleared by user for general purpose usage. Set by user for general purpose usage. General purpose Flag Cleared by user for general purpose usage. Set by user for general purpose usage. Power-Down mode bit Cleared by hardware when reset occurs. Set to enter power-down mode. Idle mode bit Cleared by hardware when interrupt or reset occurs. Set to enter idle mode. 5 4 POF 3 GF1 2 GF0 1 PD 0 IDL 5 - 4 POF 3 GF1 2 GF0 1 PD 0 IDL Reset Value = 00X1 0000b Not bit addressable Power-off flag reset value will be 1 only after a power on (cold reset). A warm reset doesn’t affect the value of this bit. 62 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Table 46. BDRCON Register BDRCON - Baud Rate Control Register (9Bh) 7 Bit Number 7 6 Bit Mnemonic 5 4 BRR 3 TBCK 2 RBCK 1 SPD 0 SRC Description Reserved The value read from this bit is indeterminate. Do not set this bit Reserved The value read from this bit is indeterminate. Do not set this bit Reserved The value read from this bit is indeterminate. Do not set this bit. Baud Rate Run Control bit Cleared to stop the internal Baud Rate Generator. Set to start the internal Baud Rate Generator. Transmission Baud rate Generator Selection bit for UART Cleared to select Timer 1 or Timer 2 for the Baud Rate Generator. Set to select internal Baud Rate Generator. Reception Baud Rate Generator Selection bit for UART Cleared to select Timer 1 or Timer 2 for the Baud Rate Generator. Set to select internal Baud Rate Generator. Baud Rate Speed Control bit for UART Cleared to select the SLOW Baud Rate Generator. Set to select the FAST Baud Rate Generator. Baud Rate Source select bit in Mode 0 for UART 6 - 5 - 4 BRR 3 TBCK 2 RBCK 1 SPD 0 SRC Cleared to select FOSC/12 as the Baud Rate Generator (FCLK PERIPH/6 in X2 mode). Set to select the internal Baud Rate Generator for UARTs in mode 0. Reset Value = XXX0 0000b Not bit addressablef 63 4289A–8051–09/03 Interrupt System The AT89C51ID2 has a total of 10 interrupt vectors: two external interrupts (INT0 and INT1), three timer interrupts (timers 0, 1 and 2), the serial port interrupt, SPI interrupt, Keyboard interrupt and the PCA global interrupt. These interrupts are shown in Figure 26. Figure 26. Interrupt Control System IPH, IPL 3 INT0 IE0 0 3 TF0 0 3 INT1 IE1 0 3 TF1 0 3 PCA IT 0 RI TI 3 0 3 0 3 KBD IT 0 3 TWI IT 0 3 SPI IT 0 Low priority interrupt Individual Enable Global Disable Interrupt polling sequence, decreasing from high to low priority High priority interrupt TF2 EXF2 Each of the interrupt sources can be individually enabled or disabled by setting or clearing a bit in the Interrupt Enable register (Table 51 and Table 49). This register also contains a global disable bit, which must be cleared to disable all interrupts at once. Each interrupt source can also be individually programmed to one out of four priority levels by setting or clearing a bit in the Interrupt Priority register (Table 52) and in the Interrupt Priority High register (Table 50 and Table 51) shows the bit values and priority levels associated with each combination. 64 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Registers The PCA interrupt vector is located at address 0033H, the SPI interrupt vector is located at address 0043H and Keyboard interrupt vector is located at address 004BH. All other vectors addresses are the same as standard C52 devices. Table 47. Priority Level Bit Values IPH. x 0 0 1 1 IPL. x 0 1 0 1 Interrupt Level Priority 0 (Lowest) 1 2 3 (Highest) A low-priority interrupt can be interrupted by a high priority interrupt, but not by another low-priority interrupt. A high-priority interrupt can’t be interrupted by any other interrupt source. If two interrupt requests of different priority levels are received simultaneously, the request of higher priority level is serviced. If interrupt requests of the same priority level are received simultaneously, an internal polling sequence determines which request is serviced. Thus within each priority level there is a second priority structure determined by the polling sequence. 65 4289A–8051–09/03 Table 48. IENO Register IEN0 - Interrupt Enable Register (A8h) 7 EA Bit Number 6 EC Bit Mnemonic Description Enable All interrupt bit Cleared to disable all interrupts. Set to enable all interrupts. PCA interrupt enable bit 6 EC Cleared to disable. Set to enable. Timer 2 overflow interrupt Enable bit Cleared to disable timer 2 overflow interrupt. Set to enable timer 2 overflow interrupt. Serial port Enable bit Cleared to disable serial port interrupt. Set to enable serial port interrupt. Timer 1 overflow interrupt Enable bit Cleared to disable timer 1 overflow interrupt. Set to enable timer 1 overflow interrupt. External interrupt 1 Enable bit Cleared to disable external interrupt 1. Set to enable external interrupt 1. Timer 0 overflow interrupt Enable bit Cleared to disable timer 0 overflow interrupt. Set to enable timer 0 overflow interrupt. External interrupt 0 Enable bit Cleared to disable external interrupt 0. Set to enable external interrupt 0. 5 ET2 4 ES 3 ET1 2 EX1 1 ET0 0 EX0 7 EA 5 ET2 4 ES 3 ET1 2 EX1 1 ET0 0 EX0 Reset Value = 0000 0000b Bit addressable 66 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Table 49. IPL0 Register IPL0 - Interrupt Priority Register (B8h) 7 Bit Number 7 6 PPCL Bit Mnemonic Description Reserved The value read from this bit is indeterminate. Do not set this bit. PCA interrupt Priority bit Refer to PPCH for priority level. Timer 2 overflow interrupt Priority bit Refer to PT2H for priority level. Serial port Priority bit Refer to PSH for priority level. Timer 1 overflow interrupt Priority bit Refer to PT1H for priority level. External interrupt 1 Priority bit Refer to PX1H for priority level. Timer 0 overflow interrupt Priority bit Refer to PT0H for priority level. External interrupt 0 Priority bit Refer to PX0H for priority level. 5 PT2L 4 PSL 3 PT1L 2 PX1L 1 PT0L 0 PX0L 6 PPCL 5 PT2L 4 PSL 3 PT1L 2 PX1L 1 PT0L 0 PX0L Reset Value = X000 0000b Bit addressable 67 4289A–8051–09/03 Table 50. IPH0 Register IPH0 - Interrupt Priority High Register (B7h) 7 Bit Number 7 6 PPCH Bit Mnemonic Description Reserved The value read from this bit is indeterminate. Do not set this bit. PCA interrupt Priority high bit. PPCHPPCLPriority Level 0 0Lowest 01 10 1 1Highest Timer 2 overflow interrupt Priority High bit PT2HPT2LPriority Level 0 0Lowest 01 10 1 1Highest Serial port Priority High bit PSH PSLPriority Level 0 0Lowest 01 10 1 1Highest Timer 1 overflow interrupt Priority High bit PT1HPT1L Priority Level 0 0 Lowest 01 10 1 1Highest External interrupt 1 Priority High bit PX1HPX1LPriority Level 0 0Lowest 01 10 1 1Highest Timer 0 overflow interrupt Priority High bit PT0HPT0LPriority Level 0 0Lowest 01 10 1 1Highest External interrupt 0 Priority High bit PX0H PX0LPriority Level 0 0Lowest 01 10 1 1Highest 5 PT2H 4 PSH 3 PT1H 2 PX1H 1 PT0H 0 PX0H 6 PPCH 5 PT2H 4 PSH 3 PT1H 2 PX1H 1 PT0H 0 PX0H Reset Value = X000 0000b Not bit addressable 68 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Table 51. IEN1 Register IEN1 - Interrupt Enable Register (B1h) 7 Bit Number 7 6 5 4 3 6 Bit Mnemonic Description Reserved Reserved Reserved Reserved Reserved SPI interrupt Enable bit Cleared to disable SPI interrupt. Set to enable SPI interrupt. TWI interrupt Enable bit 1 ETWI Cleared to disable TWI interrupt. Set to enable TWI interrupt. Keyboard interrupt Enable bit Cleared to disable keyboard interrupt. Set to enable keyboard interrupt. 5 4 3 2 ESPI 1 ETWI 0 EKBD 2 ESPI 0 EKBD Reset Value = XXXX X000b Bit addressable 69 4289A–8051–09/03 Table 52. IPL1 Register IPL1 - Interrupt Priority Register (B2h) Table 53. 7 Bit Number 7 6 Bit Mnemonic Description Reserved The value read from this bit is indeterminate. Do not set this bit. Reserved The value read from this bit is indeterminate. Do not set this bit. Reserved The value read from this bit is indeterminate. Do not set this bit. Reserved The value read from this bit is indeterminate. Do not set this bit. Reserved The value read from this bit is indeterminate. Do not set this bit. SPI interrupt Priority bit Refer to SPIH for priority level. TWI interrupt Priority bit Refer to TWIH for priority level. Keyboard interrupt Priority bit Refer to KBDH for priority level. 5 4 3 2 SPIL 1 TWIL 0 KBDL 6 - 5 - 4 - 3 - 2 SPIL 1 TWIL 0 KBDL Reset Value = XXXX X000b Bit addressable 70 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Table 54. IPH1 Register IPH1 - Interrupt Priority High Register (B3h) 7 Bit Number 7 6 Bit Mnemonic Description Reserved The value read from this bit is indeterminate. Do not set this bit. Reserved The value read from this bit is indeterminate. Do not set this bit. Reserved The value read from this bit is indeterminate. Do not set this bit. Reserved The value read from this bit is indeterminate. Do not set this bit. Reserved The value read from this bit is indeterminate. Do not set this bit. SPI interrupt Priority High bit SPIH SPILPriority Level 0 0Lowest 0 1 1 0 1 1Highest TWI interrupt Priority High bit TWILPriority Level TWIH 0 0Lowest 0 1 1 0 1 1Highest Keyboard interrupt Priority High bit KB DH KBDLPriority Level 0 0 Lowest 0 1 1 0 1 1Highest 5 4 3 2 SPIH 1 TWIH 0 KBDH 6 - 5 - 4 - 3 - 2 SPIH 1 TWIH 0 KBDH Reset Value = XXXX X000b Not bit addressable 71 4289A–8051–09/03 Interrupt Sources and Vector Addresses Table 55. Interrupt Sources and Vector Addresses Number 0 1 2 3 4 5 6 7 8 9 9 Polling Priority 0 1 2 3 4 6 7 5 8 9 9 Interrupt Source Reset INT0 Timer 0 INT1 Timer 1 UART Timer 2 PCA Keyboard TWI SPI IE0 TF0 IE1 IF1 RI+TI TF2+EXF2 CF + CCFn (n = 0-4) KBDIT TWIIT SPIIT Interrupt Request Vector Address 0000h 0003h 000Bh 0013h 001Bh 0023h 002Bh 0033h 003Bh 0043h 004Bh 72 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Power Management Introduction Two power reduction modes are implemented in the AT89C51ID2. The Idle mode and the Power-Down mode. These modes are detailed in the following sections. In addition to these power reduction modes, the clocks of the core and peripherals can be dynamically divided by 2 using the X2 mode detailed in Section “Enhanced Features”, page 22. Idle Mode Idle mode is a power reduction mode that reduces the power consumption. In this mode, program execution halts. Idle mode freezes the clock to the CPU at known states while the peripherals continue to be clocked. The CPU status before entering Idle mode is preserved, i.e., the program counter and program status word register retain their data for the duration of Idle mode. The contents of the SFRs and RAM are also retained. The status of the Port pins during Idle mode is detailed in Table 56. To enter Idle mode, set the IDL bit in PCON register (see Table 57). The AT89C51ID2 enters Idle mode upon execution of the instruction that sets IDL bit. The instruction that sets IDL bit is the last instruction executed. Note: If IDL bit and PD bit are set simultaneously, the AT89C51ID2 enters Power-Down mode. Then it does not go in Idle mode when exiting Power-Down mode. Entering Idle Mode Exiting Idle Mode There are two ways to exit Idle mode: 1. Generate an enabled interrupt. – Hardware clears IDL bit in PCON register which restores the clock to the CPU. Execution resumes with the interrupt service routine. Upon completion of the interrupt service routine, program execution resumes with the instruction immediately following the instruction that activated Idle mode. The general purpose flags (GF1 and GF0 in PCON register) may be used to indicate whether an interrupt occurred during normal operation or during Idle mode. When Idle mode is exited by an interrupt, the interrupt service routine may examine GF1 and GF0. A logic high on the RST pin clears IDL bit in PCON register directly and asynchronously. This restores the clock to the CPU. Program execution momentarily resumes with the instruction immediately following the instruction that activated the Idle mode and may continue for a number of clock cycles before the internal reset algorithm takes control. Reset initializes the AT89C51ID2 and vectors the CPU to address C:0000h. During the time that execution resumes, the internal RAM cannot be accessed; however, it is possible for the Port pins to be accessed. To avoid unexpected outputs at the Port pins, the instruction immediately following the instruction that activated Idle mode should not write to a Port pin or to the external RAM. 2. Generate a reset. – Note: Power-Down Mode The Power-Down mode places the AT89C51ID2 in a very low power state. Power-Down mode stops the oscillator, freezes all clock at known states. The CPU status prior to entering Power-Down mode is preserved, i.e., the program counter, program status word register retain their data for the duration of Power-Down mode. In addition, the SFR 73 4289A–8051–09/03 and RAM contents are preserved. The status of the Port pins during Power-Down mode is detailed in Table 56. Note: VCC may be reduced to as low as VRET during Power-Down mode to further reduce power dissipation. Take care, however, that VDD is not reduced until Power-Down mode is invoked. Entering Power-Down Mode To enter Power-Down mode, set PD bit in PCON register. The AT89C51ID2 enters the Power-Down mode upon execution of the instruction that sets PD bit. The instruction that sets PD bit is the last instruction executed. Exiting Power-Down Mode Note: If VCC was reduced during the Power-Down mode, do not exit Power-Down mode until VCC is restored to the normal operating level. There are two ways to exit the Power-Down mode: 1. Generate an enabled external interrupt. – The AT89C51ID2 provides capability to exit from Power-Down using INT0#, INT1#. Hardware clears PD bit in PCON register which starts the oscillator and restores the clocks to the CPU and peripherals. Using INTx# input, execution resumes when the input is released (see Figure 27). Execution resumes with the interrupt service routine. Upon completion of the interrupt service routine, program execution resumes with the instruction immediately following the instruction that activated Power-Down mode. The external interrupt used to exit Power-Down mode must be configured as level sensitive (INT0# and INT1#) and must be assigned the highest priority. In addition, the duration of the interrupt must be long enough to allow the oscillator to stabilize. The execution will only resume when the interrupt is deasserted. Exit from power-down by external interrupt does not affect the SFRs nor the internal RAM content. Note: Note: Figure 27. Power-Down Exit Waveform Using INT1:0# INT1:0# OSC Active phase Power-down phase Oscillator restart phase Active phase 2. Generate a reset. – A logic high on the RST pin clears PD bit in PCON register directly and asynchronously. This starts the oscillator and restores the clock to the CPU and peripherals. Program execution momentarily resumes with the instruction immediately following the instruction that activated Power-Down mode and may continue for a number of clock cycles before the internal reset algorithm takes control. Reset initializes the AT89C51ID2 and vectors the CPU to address 0000h. During the time that execution resumes, the internal RAM cannot be accessed; however, it is possible for the Port pins to be accessed. To avoid unexpected outputs at the Port Note: 74 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 pins, the instruction immediately following the instruction that activated the Power-Down mode should not write to a Port pin or to the external RAM. Note: Exit from power-down by reset redefines all the SFRs, but does not affect the internal RAM content. Table 56. Pin Conditions in Special Operating Modes Mode Reset Idle (internal code) Idle (external code) PowerDown(inter nal code) PowerDown (external code) Port 0 Floating Port 1 High Port 2 High Port 3 High Port 4 High ALE High PSEN# High Data Data Data Data Data High High Floating Data Data Data Data High High Data Data Data Data Data Low Low Floating Data Data Data Data Low Low 75 4289A–8051–09/03 Registers Table 57. PCON Register PCON (S87:h) Power configuration Register 7 Bit Number 7-5 6 5 4 POF 3 GF1 2 GF0 1 PD 0 IDL Bit Mnemonic Description Reserved The value read from these bits is indeterminate. Do not set these bits. Power-Off Flag Cleared to recognize next reset type. Set by hardware when VCC rises from 0 to its nominal voltage. Can also be set by software. General Purpose flag 1 One use is to indicate whether an interrupt occurred during normal operation or during Idle mode. General Purpose flag 0 One use is to indicate whether an interrupt occurred during normal operation or during Idle mode. Power-Down Mode bit Cleared by hardware when an interrupt or reset occurs. Set to activate the Power-Down mode. If IDL and PD are both set, PD takes precedence. Idle Mode bit Cleared by hardware when an interrupt or reset occurs. Set to activate the Idle mode. If IDL and PD are both set, PD takes precedence. 4 POF 3 GF1 2 GF0 1 PD 0 IDL Reset Value= XXXX 0000b 76 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Keyboard Interface The AT89C51ID2 implements a keyboard interface allowing the connection of a 8 x n matrix keyboard. It is based on 8 inputs with programmable interrupt capability on both high or low level. These inputs are available as alternate function of P1 and allow to exit from idle and power down modes. The keyboard interface interfaces with the C51 core through 3 special function registers: KBLS, the Keyboard Level Selection register (Table 60), KBE, The Keyboard interrupt Enable register (Table 59), and KBF, the Keyboard Flag register (Table 58). Interrupt The keyboard inputs are considered as 8 independent interrupt sources sharing the same interrupt vector. An interrupt enable bit (KBD in IE1) allows global enable or disable of the keyboard interrupt (see Figure 28). As detailed in Figure 29 each keyboard input has the capability to detect a programmable level according to KBLS. x bit value. Level detection is then reported in interrupt flags KBF. x that can be masked by software using KBE. x bits. This structure allow keyboard arrangement from 1 by n to 8 by n matrix and allow usage of P1 inputs for other purpose. Figure 28. Keyboard Interface Block Diagram Vcc 0 P1:x 1 Internal Pullup KBF. x KBE. x KBLS. x Figure 29. Keyboard Input Circuitry P1.0 P1.1 P1.2 P1.3 P1.4 P1.5 P1.6 P1.7 Input Circuitry Input Circuitry Input Circuitry Input Circuitry KBDIT Input Circuitry Input Circuitry Input Circuitry Input Circuitry KBD IE1 Keyboard Interface Interrupt Request Power Reduction Mode P1 inputs allow exit from idle and power down modes as detailed in Section “Power Management”, page 73. 77 4289A–8051–09/03 Registers Table 58. KBF Register KBF-Keyboard Flag Register (9Eh) 7 KBF7 Bit Number 6 KBF6 5 KBF5 4 KBF4 3 KBF3 2 KBF2 1 KBF1 0 KBF0 Bit Mnemonic Description Keyboard line 7 flag Set by hardware when the Port line 7 detects a programmed level. It generates a Keyboard interrupt request if the KBKBIE. 7 bit in KBIE register is set. Must be cleared by software. Keyboard line 6 flag Set by hardware when the Port line 6 detects a programmed level. It generates a Keyboard interrupt request if the KBIE. 6 bit in KBIE register is set. Must be cleared by software. Keyboard line 5 flag Set by hardware when the Port line 5 detects a programmed level. It generates a Keyboard interrupt request if the KBIE. 5 bit in KBIE register is set. Must be cleared by software. Keyboard line 4 flag Set by hardware when the Port line 4 detects a programmed level. It generates a Keyboard interrupt request if the KBIE. 4 bit in KBIE register is set. Must be cleared by software. Keyboard line 3 flag Set by hardware when the Port line 3 detects a programmed level. It generates a Keyboard interrupt request if the KBIE. 3 bit in KBIE register is set. Must be cleared by software. Keyboard line 2 flag Set by hardware when the Port line 2 detects a programmed level. It generates a Keyboard interrupt request if the KBIE. 2 bit in KBIE register is set. Must be cleared by software. Keyboard line 1 flag Set by hardware when the Port line 1 detects a programmed level. It generates a Keyboard interrupt request if the KBIE. 1 bit in KBIE register is set. Must be cleared by software. Keyboard line 0 flag Set by hardware when the Port line 0 detects a programmed level. It generates a Keyboard interrupt request if the KBIE. 0 bit in KBIE register is set. Must be cleared by software. 7 KBF7 6 KBF6 5 KBF5 4 KBF4 3 KBF3 2 KBF2 1 KBF1 0 KBF0 Reset Value= 0000 0000b 78 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Table 59. KBE Register KBE-Keyboard Input Enable Register (9Dh) 7 KBE7 Bit Number 6 KBE6 5 KBE5 4 KBE4 3 KBE3 2 KBE2 1 KBE1 0 KBE0 Bit Mnemonic Description Keyboard line 7 Enable bit Cleared to enable standard I/O pin. Set to enable KBF. 7 bit in KBF register to generate an interrupt request. Keyboard line 6 Enable bit Cleared to enable standard I/O pin. Set to enable KBF. 6 bit in KBF register to generate an interrupt request. Keyboard line 5 Enable bit Cleared to enable standard I/O pin. Set to enable KBF. 5 bit in KBF register to generate an interrupt request. Keyboard line 4 Enable bit Cleared to enable standard I/O pin. Set to enable KBF. 4 bit in KBF register to generate an interrupt request. Keyboard line 3 Enable bit Cleared to enable standard I/O pin. Set to enable KBF. 3 bit in KBF register to generate an interrupt request. Keyboard line 2 Enable bit Cleared to enable standard I/O pin. Set to enable KBF. 2 bit in KBF register to generate an interrupt request. Keyboard line 1 Enable bit Cleared to enable standard I/O pin. Set to enable KBF. 1 bit in KBF register to generate an interrupt request. Keyboard line 0 Enable bit Cleared to enable standard I/O pin. Set to enable KBF. 0 bit in KBF register to generate an interrupt request. 7 KBE7 6 KBE6 5 KBE5 4 KBE4 3 KBE3 2 KBE2 1 KBE1 0 KBE0 Reset Value= 0000 0000b 79 4289A–8051–09/03 Table 60. KBLS Register KBLS-Keyboard Level Selector Register (9Ch) 7 KBLS7 Bit Number 6 KBLS6 5 KBLS5 4 KBLS4 3 KBLS3 2 KBLS2 1 KBLS1 0 KBLS0 Bit Mnemonic Description Keyboard line 7 Level Selection bit Cleared to enable a low level detection on Port line 7. Set to enable a high level detection on Port line 7. Keyboard line 6 Level Selection bit Cleared to enable a low level detection on Port line 6. Set to enable a high level detection on Port line 6. Keyboard line 5 Level Selection bit Cleared to enable a low level detection on Port line 5. Set to enable a high level detection on Port line 5. Keyboard line 4 Level Selection bit Cleared to enable a low level detection on Port line 4. Set to enable a high level detection on Port line 4. Keyboard line 3 Level Selection bit Cleared to enable a low level detection on Port line 3. Set to enable a high level detection on Port line 3. Keyboard line 2 Level Selection bit Cleared to enable a low level detection on Port line 2. Set to enable a high level detection on Port line 2. Keyboard line 1 Level Selection bit Cleared to enable a low level detection on Port line 1. Set to enable a high level detection on Port line 1. Keyboard line 0 Level Selection bit Cleared to enable a low level detection on Port line 0. Set to enable a high level detection on Port line 0. 7 KBLS7 6 KBLS6 5 KBLS5 4 KBLS4 3 KBLS3 2 KBLS2 1 KBLS1 0 KBLS0 Reset Value= 0000 0000b 80 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 2-wire Interface (TWI) This section describes the 2-wire interface. The 2-wire bus is a bi-directional 2-wire serial communication standard. It is designed primarily for simple but efficient integrated circuit (IC) control. The system is comprised of two lines, SCL (Serial Clock) and SDA (Serial Data) that carry information between the ICs connected to them. The serial data transfer is limited to 400 Kbit/s in standard mode. Various communication configuration can be designed using this bus. Figure 30 shows a typical 2-wire bus configuration. All the devices connected to the bus can be master and slave. Figure 30. 2-wire Bus Configuration device1 device2 device3 ... deviceN SCL SDA 81 4289A–8051–09/03 Figure 31. Block Diagram 8 SSADR Address Register Input Filter SDA PI2.1 Comparator Output Stage SSDAT Shift Register ACK 8 Input Filter SCL PI2.0 Arbitration & Sink Logic Timing & Control logic Serial clock generator Timer 1 overflow SSCON FCLK PERIPH/4 Output Stage Interrupt Control Register 7 Status Bits Status Decoder SSCS Status Register 8 82 AT89C51ID2 4289A–8051–09/03 Internal Bus AT89C51ID2 Description The CPU interfaces to the 2-wire logic via the following four 8-bit special function registers: the Synchronous Serial Control register (SSCON; Table 70), the Synchronous Serial Data register (SSDAT; Table 71), the Synchronous Serial Control and Status register (SSCS; Table 72) and the Synchronous Serial Address register (SSADR Table 75). SSCON is used to enable the TWI interface, to program the bit rate (see Table 63), to enable slave modes, to acknowledge or not a received data, to send a START or a STOP condition on the 2-wire bus, and to acknowledge a serial interrupt. A hardware reset disables the TWI module. SSCS contains a status code which reflects the status of the 2-wire logic and the 2-wire bus. The three least significant bits are always zero. The five most significant bits contains the status code. There are 26 possible status codes. When SSCS contains F8h, no relevant state information is available and no serial interrupt is requested. A valid status code is available in SSCS one machine cycle after SI is set by hardware and is still present one machine cycle after SI has been reset by software. to Table 69. give the status for the master modes and miscellaneous states. SSDAT contains a byte of serial data to be transmitted or a byte which has just been received. It is addressable while it is not in process of shifting a byte. This occurs when 2-wire logic is in a defined state and the serial interrupt flag is set. Data in SSDAT remains stable as long as SI is set. While data is being shifted out, data on the bus is simultaneously shifted in; SSDAT always contains the last byte present on the bus. SSADR may be loaded with the 7-bit slave address (7 most significant bits) to which the TWI module will respond when programmed as a slave transmitter or receiver. The LSB is used to enable general call address (00h) recognition. Figure 32 shows how a data transfer is accomplished on the 2-wire bus. Figure 32. Complete Data Transfer on 2-wire Bus SDA MSB acknowledgement signal from receiver SCL S start condition 1 2 7 8 9 ACK 1 2 3-8 acknowledgement signal from receiver 9 ACK clock line held low while interrupts are serviced P stop condition The four operating modes are: • • • • Master Transmitter Master Receiver Slave transmitter Slave receiver Data transfer in each mode of operation is shown in Table to Table 69 and Figure 33. to Figure 36.. These figures contain the following abbreviations: S : START condition R : Read bit (high level at SDA) 83 4289A–8051–09/03 W: Write bit (low level at SDA) A: Acknowledge bit (low level at SDA) A: Not acknowledge bit (high level at SDA) Data: 8-bit data byte P : STOP condition In Figure 33 to Figure 36, circles are used to indicate when the serial interrupt flag is set. The numbers in the circles show the status code held in SSCS. At these points, a service routine must be executed to continue or complete the serial transfer. These service routines are not critical since the serial transfer is suspended until the serial interrupt flag is cleared by software. When the serial interrupt routine is entered, the status code in SSCS is used to branch to the appropriate service routine. For each status code, the required software action and details of the following serial transfer are given in Table to Table 69. Master Transmitter Mode In the master transmitter mode, a number of data bytes are transmitted to a slave receiver (Figure 33). Before the master transmitter mode can be entered, SSCON must be initialised as follows: Table 61. SSCON Initialization CR2 bit rate SSIE 1 STA 0 STO 0 SI 0 AA X CR1 bit rate CR0 bit rate CR0, CR1 and CR2 define the internal serial bit rate if external bit rate generator is not used. SSIE must be set to enable TWI. STA, STO and SI must be cleared. The master transmitter mode may now be entered by setting the STA bit. The 2-wire logic will now test the 2-wire bus and generate a START condition as soon as the bus becomes free. When a START condition is transmitted, the serial interrupt flag (SI bit in SSCON) is set, and the status code in SSCS will be 08h. This status must be used to vector to an interrupt routine that loads SSDAT with the slave address and the data direction bit (SLA+W). When the slave address and the direction bit have been transmitted and an acknowledgement bit has been received, SI is set again and a number of status code in SSCS are possible. There are 18h, 20h or 38h for the master mode and also 68h, 78h or B0h if the slave mode was enabled (AA=logic 1). The appropriate action to be taken for each of these status code is detailed in Table . This scheme is repeated until a STOP condition is transmitted. SSIE, CR2, CR1 and CR0 are not affected by the serial transfer and are referred to Table 7 to Table 11. After a repeated START condition (state 10h) the TWI module may switch to the master receiver mode by loading SSDAT with SLA+R. Master Receiver Mode In the master receiver mode, a number of data bytes are received from a slave transmitter (Figure 34). The transfer is initialized as in the master transmitter mode. When the START condition has been transmitted, the interrupt routine must load SSDAT with the 7-bit slave address and the data direction bit (SLA+R). The serial interrupt flag SI must then be cleared before the serial transfer can continue. 84 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 When the slave address and the direction bit have been transmitted and an acknowledgement bit has been received, the serial interrupt flag is set again and a number of status code in SSCS are possible. There are 40h, 48h or 38h for the master mode and also 68h, 78h or B0h if the slave mode was enabled (AA=logic 1). The appropriate action to be taken for each of these status code is detailed in Table . This scheme is repeated until a STOP condition is transmitted. SSIE, CR2, CR1 and CR0 are not affected by the serial transfer and are referred to Table 7 to Table 11. After a repeated START condition (state 10h) the TWI module may switch to the master transmitter mode by loading SSDAT with SLA+W. Slave Receiver Mode In the slave receiver mode, a number of data bytes are received from a master transmitter (Figure 35). To initiate the slave receiver mode, SSADR and SSCON must be loaded as follows: Table 62. SSADR: Slave Receiver Mode Initialization A6 A5 A4 A3 own slave address A2 A1 A0 GC The upper 7 bits are the address to which the TWI module will respond when addressed by a master. If the LSB (GC) is set the TWI module will respond to the general call address (00h); otherwise it ignores the general call address. Table 63. SSCON: Slave Receiver Mode Initialization CR2 bit rate SSIE 1 STA 0 STO 0 SI 0 AA 1 CR1 bit rate CR0 bit rate CR0, CR1 and CR2 have no effect in the slave mode. SSIE must be set to enable the TWI. The AA bit must be set to enable the own slave address or the general call address acknowledgement. STA, STO and SI must be cleared. When SSADR and SSCON have been initialised, the TWI module waits until it is addressed by its own slave address followed by the data direction bit which must be at logic 0 (W) for the TWI to operate in the slave receiver mode. After its own slave address and the W bit have been received, the serial interrupt flag is set and a valid status code can be read from SSCS. This status code is used to vector to an interrupt service routine.The appropriate action to be taken for each of these status code is detailed in Table . The slave receiver mode may also be entered if arbitration is lost while TWI is in the master mode (states 68h and 78h). If the AA bit is reset during a transfer, TWI module will return a not acknowledge (logic 1) to SDA after the next received data byte. While AA is reset, the TWI module does not respond to its own slave address. However, the 2-wire bus is still monitored and address recognition may be resume at any time by setting AA. This means that the AA bit may be used to temporarily isolate the module from the 2-wire bus. Slave Transmitter Mode In the slave transmitter mode, a number of data bytes are transmitted to a master receiver (Figure 36). Data transfer is initialized as in the slave receiver mode. When SSADR and SSCON have been initialized, the TWI module waits until it is addressed by 85 4289A–8051–09/03 its own slave address followed by the data direction bit which must be at logic 1 (R) for TWI to operate in the slave transmitter mode. After its own slave address and the R bit have been received, the serial interrupt flag is set and a valid status code can be read from SSCS. This status code is used to vector to an interrupt service routine. The appropriate action to be taken for each of these status code is detailed in Table . The slave transmitter mode may also be entered if arbitration is lost while the TWI module is in the master mode. If the AA bit is reset during a transfer, the TWI module will transmit the last byte of the transfer and enter state C0h or C8h. the TWI module is switched to the not addressed slave mode and will ignore the master receiver if it continues the transfer. Thus the master receiver receives all 1’s as serial data. While AA is reset, the TWI module does not respond to its own slave address. However, the 2-wire bus is still monitored and address recognition may be resume at any time by setting AA. This means that the AA bit may be used to temporarily isolate the TWI module from the 2-wire bus. Miscellaneous States There are two SSCS codes that do not correspond to a define TWI hardware state (Table 69 ). These codes are discuss hereafter. Status F8h indicates that no relevant information is available because the serial interrupt flag is not set yet. This occurs between other states and when the TWI module is not involved in a serial transfer. Status 00h indicates that a bus error has occurred during a TWI serial transfer. A bus error is caused when a START or a STOP condition occurs at an illegal position in the format frame. Examples of such illegal positions happen during the serial transfer of an address byte, a data byte, or an acknowledge bit. When a bus error occurs, SI is set. To recover from a bus error, the STO flag must be set and SI must be cleared. This causes the TWI module to enter the not addressed slave mode and to clear the STO flag (no other bits in SSCON are affected). The SDA and SCL lines are released and no STOP condition is transmitted. Notes the TWI module interfaces to the external 2-wire bus via two port pins: SCL (serial clock line) and SDA (serial data line). To avoid low level asserting on these lines when the TWI module is enabled, the output latches of SDA and SLC must be set to logic 1. Table 64. Bit Frequency Configuration Bit Frequency ( kHz) CR2 0 0 0 0 1 1 1 1 CR1 0 0 1 1 0 0 1 1 CR0 0 1 0 1 0 1 0 1 FOSCA= 12 MHz 47 53.5 62.5 75 100 200 0.5 Application execution The BLJB is a fuse bit in the Hardware Byte. That can be modified by hardware (programmer) or by software (API). Note: The BLJB test is perform by hardware to prevent any program execution.. The Software Boot Vector contains the high address of custumer bootloader stored in the application. SBV = FCh (default value) if no custumer bootloader in user Flash. SBV Note: The costumer bootloader is called by JMP [SBV]00h instruction. BLJB 124 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Boot Process Figure 49. Bootloader Process RESET If BLJB=0 then ENBOOT bit (AUXR1) is set else ENBOOT bit (AUXR1) is cleared Yes (PSEN = 0, EA = 1, and ALE =1 or not connected) Hardware Hardware condition? FCON = 00h FCON = F0h BLJB=1 ENBOOT=0 BLJB!= 0 ? BLJB=0 ENBOOT=1 F800h Software FCON = 00h ? yes = hardware boot conditions BSB = 00h ? PC=0000h USER APPLICATION SBV = FCh ? USER BOOT LOADER Atmel BOOT LOADER PC= [SBV]00h 125 4289A–8051–09/03 ISP Protocol Description Physical Layer The UART used to transmit information has the following configuration: • • • • • Character: 8-bit data Parity: none Stop: 2 bits Flow control: none Baudrate: autobaud is performed by the bootloader to compute the baudrate choosen by the host. Frame Description The Serial Protocol is based on the Intel Hex-type records. Intel Hex records consist of ASCII characters used to represent hexadecimal values and are summarized below Figure 50. Intel Hex Type Frame Record Mark ’:’ 1-byte Reclen 1-byte Load Offset 2-bytes Record Type 1-byte Data or Info Checksum n-bytes 1-byte • • Record Mark: Reclen: Record Mark is the start of frame. This field must contain ’:’. Reclen specifies the number of bytes of information or data which follows the Record Type field of the record. • Load Offset: Load Offset specifies the 16-bit starting load offset of the data bytes, therefore this field is used only for Data Program Record (see Section “ISP Commands Summary”). • Record Type: Record Type specifies the command type. This field is used to interpret the remaining information within the frame. The encoding for all the current record types is described in Section “ISP Commands Summary”. • Data/Info: Data/Info is a variable length field. It consists of zero or more bytes encoded as pairs of hexadecimal digits. The meaning of data depends on the Record Type. • Checksum: The two’s complement of the 8-bit bytes that result from converting each pair of ASCII hexadecimal digits to one byte of binary, and including the Reclen field to and including the last byte of the Data/Info field. Therefore, the sum of all the ASCII pairs in a record after converting to binary, from the Reclen field to and including the Checksum field, is zero. 126 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Functional Description Software Security Bits (SSB) The SSB protects any Flash access from ISP command. The command "Program Software Security bit" can only write a higher priority level. There are three levels of security: • level 0: NO_SECURITY (FFh) This is the default level. From level 0, one can write level 1 or level 2. • level 1: WRITE_SECURITY (FEh ) For this level it is impossible to write in the Flash memory, BSB and SBV. The Bootloader returns ’P’ on write access. From level 1, one can write only level 2. • level 2: RD_WR_SECURITY (FCh The level 2 forbids all read and write accesses to/from the Flash/EEPROM memory. The Bootloader returns ’L’ on read or write access. Only a full chip erase in parallel mode (using a programmer) or ISP command can reset the software security bits. From level 2, one cannot read and write anything. Table 93. Software Security Byte Behavior Level 0 Flash/EEprom Fuse bit BSB & SBV SSB Manufacturer info Bootloader info Erase block Full chip erase Blank Check Any access allowed Any access allowed Any access allowed Any access allowed Read only access allowed Read only access allowed Allowed Allowed Allowed Level 1 Read only access allowed Read only access allowed Read only access allowed Write level 2 allowed Read only access allowed Read only access allowed Not allowed Allowed Allowed Level 2 Any access not allowed Any access not allowed Any access not allowed Read only access allowed Read only access allowed Read only access allowed Not allowed Allowed Allowed 127 4289A–8051–09/03 Full Chip Erase The ISP command "Full Chip Erase" erases all User Flash memory (fills with FFh) and sets some bytes used by the bootloader at their default values: • • • BSB = FFh SBV = FCh SSB = FFh and finally erase the Software Security Bits The Full Chip Erase does not affect the bootloader. Checksum Error When a checksum error is detected send ‘X’ followed with CR&LF. 128 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Flow Description Overview An initialization step must be performed after each Reset. After microcontroller reset, the bootloader waits for an autobaud sequence ( see section ‘autobaud performance’). When the communication is initialized the protocol depends on the record type requested by the host. FLIP, a software utility to implement ISP programming with a PC, is available from the Atmel the web site. Communication Initialization The host initializes the communication by sending a ’U’ character to help the bootloader to compute the baudrate (autobaud). Figure 51. Initialization Host Init communication "U" Bootloader Performs autobaud Sends back U character If (not received "U") Else Communication opened "U" Autobaud Performances The ISP feature allows a wide range of baud rates in the user application. It is also adaptable to a wide range of oscillator frequencies. This is accomplished by measuring the bit-time of a single bit in a received character. This information is then used to program the baud rate in terms of timer counts based on the oscillator frequency. The ISP feature requires that an initial character (an uppercase U) be sent to the AT89C51ID2 to establish the baud rate. Table show the autobaud capability. Table 94. Autobaud Performances Frequency (MHz) Baudrate (kHz) 2400 4800 9600 19200 38400 57600 115200 1.8432 OK OK OK OK 2 OK 2.4576 OK OK OK OK OK 3 OK OK OK OK 3.6864 OK OK OK OK OK OK 4 OK OK OK 5 OK OK OK OK 6 OK OK OK OK OK 7.3728 OK OK OK OK OK OK OK Frequency (MHz) Baudrate (kHz) 2400 8 OK 10 OK 11.0592 OK 12 OK 14.746 OK 16 OK 20 OK 24 OK 26.6 OK 129 4289A–8051–09/03 Table 94. Autobaud Performances (Continued) Frequency (MHz) Baudrate (kHz) 4800 9600 19200 38400 57600 115200 1.8432 OK OK OK 2 OK OK OK 2.4576 OK OK OK OK OK OK 3 OK OK OK OK 3.6864 OK OK OK OK OK OK 4 OK OK OK OK OK 5 OK OK OK OK OK 6 OK OK OK OK OK 7.3728 OK OK OK OK OK - Command Data Stream Protocol Figure 52. Command Flow Host All commands are sent using the same flow. Each frame sent by the host is echoed by the bootloader. Bootloader ":" ":" If (not received ":") Else Sends echo and start reception Sends first character of the Frame Sends frame (made of 2 ASCII characters per byte) Echo analysis Gets frame, and sends back ech for each received byte 130 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Write / Program Commands This flow is common to the following frames: • • • • Description Figure 53. Write/Program Flow Host Send Write Command Flash / Eeprom Programming Data Frame EOF or Atmel Frame (only Programming Atmel Frame) Config Byte Programming Data Frame Baud Rate Frame Bootloader Write Command Wait Write Command OR Wait Checksum Error Checksum error ’X’ & CR & LF Send Checksum error COMMAND ABORTED NO_SECURITY OR Wait Security Error ’P’ & CR & LF Send Security error COMMAND ABORTED Wait Programming Wait COMMAND_OK ’.’ & CR & LF Send COMMAND_OK COMMAND FINISHED Example Programming Data (write 55h at address 0010h in the Flash) HOST BOOTLOADER : 01 0010 00 55 9A : 01 0010 00 55 9A . CR LF Programming Atmel function (write SSB to level 2) HOST BOOTLOADER : 02 0000 03 05 01 F5 : 02 0000 03 05 01 F5. CR LF Writing Frame (write BSB to 55h) HOST BOOTLOADER : 03 0000 03 06 00 55 9F : 03 0000 03 06 00 55 9F . CR LF 131 4289A–8051–09/03 Blank Check Command Description Figure 54. Blank Check Flow Host Send Blank Check Command Bootloader Blank Check Command Wait Blank Check Command OR Wait Checksum Error Checksum error ’X’ & CR & LF Send Checksum error COMMAND ABORTED Flash blank OR Wait COMMAND_OK ’.’ & CR & LF Send COMMAND_OK COMMAND FINISHED Wait Address not erased address & CR & LF Send first Address not erased COMMAND FINISHED Example Blank Check ok HOST BOOTLOADER : 05 0000 04 0000 7FFF 01 78 : 05 0000 04 0000 7FFF 01 78 . CR LF Blank Check ko at address xxxx HOST BOOTLOADER : 05 0000 04 0000 7FFF 01 78 : 05 0000 04 0000 7FFF 01 78 xxxx CR LF Blank Check with checksum error HOST BOOTLOADER : 05 0000 04 0000 7FFF 01 70 : 05 0000 04 0000 7FFF 01 70 X CR LF CR LF 132 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Display Data Description Figure 55. Display Flow Host Send Display Command Bootloader Display Command Wait Display Command OR Wait Checksum Error Checksum error ’X’ & CR & LF Send Checksum Error COMMAND ABORTED RD_WR_SECURITY OR Wait Security Error ’L’ & CR & LF Send Security Error COMMAND ABORTED Read Data All data read Complet Frame Wait Display Data "Address = " "Reading value" CR & LF Send Display Data All data read All data read COMMAND FINISHED COMMAND FINISHED Note: The maximum size of block is 400h. To read more than 400h bytes, the Host must send a new command. 133 4289A–8051–09/03 Example Display data from address 0000h to 0020h HOST BOOTLOADER BOOTLOADER BOOTLOADER BOOTLOADER : 05 0000 04 0000 0020 00 D7 : 05 0000 04 0000 0020 00 D7 0000=-----data------ CR LF 0010=-----data------ CR LF 0020=data CR LF (16 data) (16 data) ( 1 data) Read Function This flow is similar for the following frames: • • Reading Frame EOF Frame/ Atmel Frame (only reading Atmel Frame) Description Figure 56. Read Flow Host Send Read Command Bootloader Read Command Wait Read Command OR Wait Checksum Error Checksum error ’X’ & CR & LF Send Checksum error COMMAND ABORTED RD_WR_SECURITY OR Wait Security Error ’L’ & CR & LF Send Security error COMMAND ABORTED Read Value Wait Value of Data ’value’ & ’.’ & CR & LF Send Data Read COMMAND FINISHED 134 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Example Read function (read SBV) HOST BOOTLOADER : 02 0000 05 07 02 F0 : 02 0000 05 07 02 F0 Value . CR LF Atmel Read function (read Bootloader version) HOST BOOTLOADER : 02 0000 01 02 00 FB : 02 0000 01 02 00 FB Value . CR LF 135 4289A–8051–09/03 ISP Commands Summary Table 95. ISP Commands Summary Command Command Name data[0] data[1] Command Effect Program Nb Data Byte. 00h Program Data Bootloader will accept up to 128 (80h) data bytes. The data bytes should be 128 byte page flash boundary. 00h 20h 01h 40h 80h C0h 00h 03h 01h 04h 05h 01h 00h 06h 01h 07h 02h 0Ah 04h 08h Data[0:1] = start address Data [2:3] = end address 04h Display Function Data[4] = 00h -> Display data Data[4] = 01h -> Blank check Blank Check Program SBV (value to write in data[2]) Full Chip Erase Program Osc fuse (value to write in data[2]) Program BLJB fuse (value to write in data[2]) Program X2 fuse (value to write in data[2]) Display Data Program SSB level 2 Program BSB (value to write in data[2]) 00h 00h 03h Write Function Erase block0 (0000h-1FFFh) Erase block1 (2000h-3FFFh) Erase block2 (4000h-7FFFh) Erase block3 (8000h- BFFFh) Erase block4 (C000h- FFFFh) Hardware Reset Ljmp Address (data[2:3]= Address) Erase SBV & BSB Program SSB level 1 136 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Table 95. ISP Commands Summary (Continued) Command Command Name data[0] data[1] 00h 01h 00h 02h 03h 00h 01h 05h Read Function 07h 02h 06h 0Bh 0Eh 01h 0Fh 00h Read Device Boot ID2 Read Bootloader Version 00h 00h Read SBV Read Extra Byte Read Hardware Byte Read Device Boot ID1 Device Id #2 Device Id #3 Read SSB Read BSB Command Effect Manufacturer Id Device Id #1 137 4289A–8051–09/03 API Call Description Several Application Program Interface (API) calls are available for use by an application program to permit selective erasing and programming of Flash pages. All calls are made through a common interface, PGM_MTP. The programming functions are selected by setting up the microcontroller’s registers before making a call to PGM_MTP at FFF0h. Results are returned in the registers. When several bytes have to be programmed, it is highly recommended to use the Atmel API “PROGRAM DATA PAGE” call. Indeed, this API call writes up to 128 bytes in a single command. All routines for software access are provided in the C Flash driver available on Atmel web site. The API calls description and arguments are shown in Table Table 96. API Call Summary Command READ MANUF ID READ DEVICE ID1 READ DEVICE ID2 READ DEVICE ID3 R1 00h 00h 00h 00h A XXh XXh XXh XXh DPTR0 0000h 0001h 0002h 0003h DPH=00h DPH=20h ERASE BLOCK 01h XXh DPH=40h DPH=80h DPH=C0h PROGRAM DATA BYTE ERASE BOOT VECTOR 02h Byte value to program XXh Address of byte to program XXh DPH=00h DPL=00h DPH=00h DPL=01h PROGRAM SSB 05h XXh DPH=00h DPL=10h DPH=00h DPL=11h PROGRAM BSB PROGRAM SBV READ SSB READ HSB READ BSB READ SBV 06h 06h 07h 07h 07h 07h New BSB value New SBV value XXh XXh XXh XXh 0000h 0001h 0000h 0004h 0001h 0002h XXh XXh XXh XXh XXh XXh none none ACC=SSB ACC=HSB ACC=BSB ACC=SBV 00h ACC= SSB value Set SSB level 0 XXh ACC=0 : DONE 00h ACC=DPH DPTR1 XXh XXh XXh XXh Returned Value Command Effect ACC=Manufacturer Id Read Manufacturer identifier ACC= Device Id 1 ACC=Device Id 2 ACC=Device Id 3 Read Device identifier 1 Read Device identifier 2 Read Device identifier 3 Erase block 0 Erase block 1 Erase block 2 Erase block 3 Erase block 4 Program one Data Byte in user flash Erase Software boot vector and boot status byte. (SBV=FCh and BSB=FFh) Set SSB level 1 04h ACC=FCh Set SSB level 2 Set SSB level 1 Program boot status byte Program software boot vector Read Software Security Byte Read Hardware Byte Read Boot Status Byte Read Software Boot Vector 138 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Table 96. API Call Summary (Continued) Command READ MANUF ID READ DEVICE ID1 READ DEVICE ID2 READ DEVICE ID3 R1 00h 00h 00h 00h A XXh XXh XXh XXh DPTR0 0000h 0001h 0002h 0003h DPH=00h DPH=20h ERASE BLOCK 01h XXh DPH=40h DPH=80h DPH=C0h PROGRAM DATA PAGE Number of byte to program Fuse value 00h or 01h Fuse value 00h or 01h XXh XXh XXh Address of the first byte to program in the Flash memory 0008h Address in XRAM of the first data to program 00h ACC=DPH DPTR1 XXh XXh XXh XXh Returned Value Command Effect ACC=Manufacturer Id Read Manufacturer identifier ACC= Device Id 1 ACC=Device Id 2 ACC=Device Id 3 Read Device identifier 1 Read Device identifier 2 Read Device identifier 3 Erase block 0 Erase block 1 Erase block 2 Erase block 3 Erase block 4 Program up to 128 bytes in user flash. ACC=0 : DONE Remark: number of bytes to program is limited such as the Flash write remains in a single 128bytes page. Hence, when ACC is 128, valid values of DPL are 00h, or, 80h. Program X2 fuse bit with ACC 09h PROGRAM X2 FUSE PROGRAM BLJB FUSE READ BOOT ID1 READ BOOT ID2 READ BOOT VERSION 0Ah XXh none 0Ah 0Eh 0Eh 0Fh 0004h DPL=00h DPL=01h XXXXh XXh XXh XXh XXh none ACC=ID1 ACC=ID2 ACC=Boot_Version Program BLJB fuse bit with ACC Read boot ID1 Read boot ID2 Read bootloader version 139 4289A–8051–09/03 Electrical Characteristics Absolute Maximum Ratings Note: I = industrial ........................................................-40°C to 85°C Storage Temperature .................................... -65°C to + 150°C Voltage on VCC to VSS (standard voltage) .........-0.5V to + 6.5V Voltage on VCC to VSS (low voltage)..................-0.5V to + 4.5V Voltage on Any Pin to VSS ..........................-0.5V to VCC + 0.5V Power Dissipation ........................................................... 1 W(2) Stresses at or above 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 any other conditions above those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions may affect device reliability. Power dissipation is based on the maximum allowable die temperature and the thermal resistance of the package. DC Parameters TA = -40°C to +85°C; VSS = 0V; VCC =2.7V to 5.5V; F = 0 to 60 MHz Symbol VIL VIH VIH1 Parameter Input Low Voltage Input High Voltage except RST, XTAL1 Input High Voltage RST, XTAL1 Min -0.5 0.2 VCC + 0.9 0.7 VCC Typ Max 0.2 VCC - 0.1 VCC + 0.5 VCC + 0.5 Unit V V V VCC = 4.5V to 5.5V 0.3 0.45 VOL Output Low Voltage, ports 1, 2, 3, 4 (6) 1.0 V V V IOL = 100 µA(4) IOL = 1.6 mA(4) IOL = 3.5 mA(4) VCC = 2.7V to 5.5V 0.45 V IOL = 0.8 mA(4) VCC = 4.5V to 5.5V 0.3 0.45 VOL1 Output Low Voltage, port 0, ALE, PSEN (6) 1.0 V V V IOL = 200 µA(4) IOL = 3.2 mA(4) IOL = 7.0 mA(4) VCC = 2.7V to 5.5V 0.45 V IOL = 1.6 mA(4) VCC = 5V ± 10% VCC - 0.3 VCC - 0.7 VOH Output High Voltage, ports 1, 2, 3, 4 VCC - 1.5 V V V IOH = -10 µA IOH = -30 µA IOH = -60 µA Test Conditions VCC = 2.7V to 5.5V 0.9 VCC V IOH = -10 µA VCC = 5V ± 10% VCC - 0.3 VCC - 0.7 VOH1 Output High Voltage, port 0, ALE, PSEN VCC - 1.5 V V V IOH = -200 µA IOH = -3.2 mA IOH = -7.0 mA VCC = 2.7V to 5.5V 0.9 VCC V IOH = -10 µA 140 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 TA = -40°C to +85°C; VSS = 0V; VCC =2.7V to 5.5V; F = 0 to 60 MHz (Continued) Symbol RRST IIL ILI ITL CIO IPD ICCOP ICCIDLE ICCWRITE tWRITE Parameter RST Pull-down Resistor Logical 0 Input Current ports 1, 2, 3, 4 and 5 Input Leakage Current Logical 1 to 0 Transition Current, ports 1, 2, 3, 4 Capacitance of I/O Buffer Power-down Current Power Supply Current on normal mode Power Supply Current on idle mode Power Supply Current on flash or EEdata write Flash or EEdata programming time 7 75 Min 50 Typ 200 (5) Max 250 -50 ±10 -650 10 150 0.4 x Frequency (MHz) + 5 0.3 x Frequency (MHz) + 5 0.8 x Frequency (MHz) + 15 10 Unit kΩ µA µA µA pF µA mA mA mA ms Test Conditions VIN = 0.45V 0.45V < VIN < VCC VIN = 2.0V FC = 3 MHz TA = 25°C 2.7 < VCC < 5.5V(3) VCC = 5.5V(1) VCC = 5.5V(2) VCC = 5.5V 2.7 < VCC < 5.5V Notes: 1. Operating ICC is measured with all output pins disconnected; XTAL1 driven with TCLCH, TCHCL = 5 ns (see Figure 60), VIL = VSS + 0.5V, VIH = VCC - 0.5V; XTAL2 N.C.; EA = RST = Port 0 = VCC. ICC would be slightly higher if a crystal oscillator used (see Figure 57). 2. Idle ICC is measured with all output pins disconnected; XTAL1 driven with TCLCH, TCHCL = 5 ns, VIL = VSS + 0.5V, VIH = VCC 0.5V; XTAL2 N.C; Port 0 = VCC; EA = RST = VSS (see Figure 58). 3. Power-down ICC is measured with all output pins disconnected; EA = VCC, PORT 0 = VCC; XTAL2 NC.; RST = VSS (see Figure 59). 4. Capacitance loading on Ports 0 and 2 may cause spurious noise pulses to be superimposed on the VOLS of ALE and Ports 1 and 3. The noise is due to external bus capacitance discharging into the Port 0 and Port 2 pins when these pins make 1 to 0 transitions during bus operation. In the worst cases (capacitive loading 100 pF), the noise pulse on the ALE line may exceed 0.45V with maxi VOL peak 0.6V. A Schmitt Trigger use is not necessary. 5. Typical values are based on a limited number of samples and are not guaranteed. The values listed are at room temperature and 5V. 6. Under steady state (non-transient) conditions, IOL must be externally limited as follows: Maximum IOL per port pin: 10 mA Maximum IOL per 8-bit port: Port 0: 26 mA Ports 1, 2 and 3: 15 mA Maximum total IOL for all output pins: 71 mA If IOL exceeds the test condition, VOL may exceed the related specification. Pins are not guaranteed to sink current greater than the listed test conditions. Figure 57. ICC Test Condition, Active Mode VCC ICC VCC VCC RST (NC) CLOCK SIGNAL XTAL2 XTAL1 VSS All other pins are disconnected. P0 EA VCC 141 4289A–8051–09/03 Figure 58. ICC Test Condition, Idle Mode VCC ICC VCC P0 RST (NC) CLOCK SIGNAL XTAL2 XTAL1 VSS All other pins are disconnected. EA VCC Figure 59. ICC Test Condition, Power-down Mode VCC ICC VCC P0 RST (NC) XTAL2 XTAL1 VSS All other pins are disconnected. EA VCC Figure 60. Clock Signal Waveform for ICC Tests in Active and Idle Modes VCC-0.5V 0.45V TCLCH TCHCL TCLCH = TCHCL = 5ns. 0.7VCC 0.2VCC-0.1 AC Parameters Explanation of the AC Symbols Each timing symbol has 5 characters. The first character is always a “T” (stands for time). The other characters, depending on their positions, stand for the name of a signal or the logical status of that signal. The following is a list of all the characters and what they stand for. Example:TAVLL = Time for Address Valid to ALE Low. TLLPL = Time for ALE Low to PSEN Low. (Load Capacitance for port 0, ALE and PSEN = 100 pF; Load Capacitance for all other outputs = 80 pF.) Table 97 Table 100, and Table 103 give the description of each AC symbols. Table 98, Table 99, Table 101 and Table 104 gives the range for each AC parameter. 142 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Table 98, Table 99 and Table 105 give the frequency derating formula of the AC parameter for each speed range description. To calculate each AC symbols. take the x value in the correponding column (-M or -L) and use this value in the formula. Example: TLLIU for -M and 20 MHz, Standard clock. x = 35 ns T 50 ns TCCIV = 4T - x = 165 ns External Program Memory Characteristics Table 97. Symbol Description Symbol T TLHLL TAVLL TLLAX TLLIV TLLPL TPLPH TPLIV TPXIX TPXIZ TAVIV TPLAZ Parameter Oscillator clock period ALE pulse width Address Valid to ALE Address Hold After ALE ALE to Valid Instruction In ALE to PSEN PSEN Pulse Width PSEN to Valid Instruction In Input Instruction Hold After PSEN Input Instruction Float After PSEN Address to Valid Instruction In PSEN Low to Address Float Table 98. AC Parameters for a Fix Clock Symbol Min T TLHLL TAVLL TLLAX TLLIV TLLPL TPLPH TPLIV TPXIX TPXIZ TAVIV TPLAZ 0 10 80 10 5 50 30 0 10 80 10 25 35 5 5 n 65 5 50 30 -M Max Min 25 35 5 5 65 -L Max ns ns ns ns ns ns ns ns ns ns ns ns Units 143 4289A–8051–09/03 Table 99. AC Parameters for a Variable Clock Symbol TLHLL TAVLL TLLAX TLLIV TLLPL TPLPH TPLIV TPXIX TPXIZ TAVIV TPLAZ Type Min Min Min Max Min Min Max Min Max Max Max Standard Clock 2T-x T-x T-x 4T-x T-x 3T-x 3T-x x T-x 5T-x x X2 Clock T-x 0.5 T - x 0.5 T - x 2T-x 0.5 T - x 1.5 T - x 1.5 T - x x 0.5 T - x 2.5 T - x x X parameter for -M range 15 20 20 35 15 25 45 0 15 45 10 X parameter for -L range 15 20 20 35 15 25 45 0 15 45 10 Units ns ns ns ns ns ns ns ns ns ns ns 144 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 External Program Memory Read Cycle 12 TCLCL TLHLL ALE TLLIV TLLPL TPLPH PSEN TLLAX TAVLL PORT 0 INSTR IN A0-A7 TAVIV PORT 2 ADDRESS OR SFR-P2 ADDRESS A8-A15 ADDRESS A8-A15 TPLIV TPLAZ TPXIX INSTR IN A0-A7 INSTR IN TPXAV TPXIZ External Data Memory Characteristics Table 100. Symbol Description Symbol TRLRH TWLWH TRLDV TRHDX TRHDZ TLLDV TAVDV TLLWL TAVWL TQVWX TQVWH TWHQX TRLAZ TWHLH Parameter RD Pulse Width WR Pulse Width RD to Valid Data In Data Hold After RD Data Float After RD ALE to Valid Data In Address to Valid Data In ALE to WR or RD Address to WR or RD Data Valid to WR Transition Data Set-up to WR High Data Hold After WR RD Low to Address Float RD or WR High to ALE high 145 4289A–8051–09/03 Table 101. AC Parameters for a Fix Clock -M Symbol TRLRH TWLWH TRLDV TRHDX TRHDZ TLLDV TAVDV TLLWL TAVWL TQVWX TQVWH TWHQX TRLAZ TWHLH 45 70 5 155 10 0 5 45 0 25 155 160 105 45 70 5 155 10 0 5 45 Min 125 125 95 0 25 155 160 105 Max Min 125 125 95 -L Max Units ns ns ns ns ns ns ns ns ns ns ns ns ns ns Table 102. AC Parameters for a Variable Clock Symbol TRLRH TWLWH TRLDV TRHDX TRHDZ TLLDV TAVDV TLLWL TLLWL TAVWL TQVWX TQVWH TWHQX TRLAZ TWHLH TWHLH Type Min Min Max Min Max Max Max Min Max Min Min Min Min Max Min Max Standard Clock 6T-x 6T-x 5T-x x 2T-x 8T-x 9T-x 3T-x 3T+x 4T-x T-x 7T-x T-x x T-x T+x X2 Clock 3T-x 3T-x 2.5 T - x x T-x 4T -x 4.5 T - x 1.5 T - x 1.5 T + x 2T-x 0.5 T - x 3.5 T - x 0.5 T - x x 0.5 T - x 0.5 T + x X parameter for -M range 25 25 30 0 25 45 65 30 30 30 20 20 15 0 20 20 X parameter for -L range 25 25 30 0 25 45 65 30 30 30 20 20 15 0 20 20 Units ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns 146 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 External Data Memory Write Cycle ALE TWHLH PSEN TLLWL TWLWH WR TLLAX PORT 0 A0-A7 TAVWL PORT 2 ADDRESS OR SFR-P2 ADDRESS A8-A15 OR SFR P2 TQVWX TQVWH DATA OUT TWHQX External Data Memory Read Cycle ALE TLLDV TWHLH PSEN TLLWL TRLRH RD TAVDV TLLAX PORT 0 A0-A7 TAVWL PORT 2 ADDRESS OR SFR-P2 TRLAZ ADDRESS A8-A15 OR SFR P2 TRHDX DATA IN TRHDZ Serial Port Timing - Shift Register Mode Table 103. Symbol Description Symbol TXLXL TQVHX TXHQX TXHDX TXHDV Parameter Serial port clock cycle time Output data set-up to clock rising edge Output data hold after clock rising edge Input data hold after clock rising edge Clock rising edge to input data valid 147 4289A–8051–09/03 Table 104. AC Parameters for a Fix Clock -M Symbol TXLXL TQVHX TXHQX TXHDX TXHDV Min 300 200 30 0 117 Max Min 300 200 30 0 117 -L Max Units ns ns ns ns ns Table 105. AC Parameters for a Variable Clock Symbol TXLXL TQVHX TXHQX TXHDX TXHDV Type Min Min Min Min Max Standard Clock 12 T 10 T - x 2T-x x 10 T - x X2 Clock 6T 5T-x T-x x 5 T- x 50 20 0 133 50 20 0 133 X Parameter For -M Range X Parameter For -L Range Units ns ns ns ns ns Shift Register Timing Waveforms INSTRUCTION ALE TXLXL CLOCK TQVXH OUTPUT DATA WRITE to SBUF INPUT DATA CLEAR RI 0 TXHDV VALID VALID 0 1 2 3 4 5 6 7 8 TXHQX 1 2 TXHDX VALID VALID VALID VALID VALID 3 4 5 6 7 SET TI VALID SET RI External Clock Drive Waveforms VCC-0.5V 0.45V 0.7VCC 0.2VCC-0.1 TCHCL TCLCX TCLCL TCHCX TCLCH 148 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 AC Testing Input/Output Waveforms INPUT/OUTPUT 0.45V VCC -0.5V 0.2 VCC + 0.9 0.2 VCC - 0.1 AC inputs during testing are driven at VCC - 0.5 for a logic “1” and 0.45V for a logic “0”. Timing measurement are made at VIH min for a logic “1” and VIL max for a logic “0”. Float Waveforms FLOAT VOH - 0.1V VOL + 0.1V VLOAD VLOAD + 0.1V VLOAD - 0.1V For timing purposes as port pin is no longer floating when a 100 mV change from load voltage occurs and begins to float when a 100 mV change from the loaded VOH/VOL level occurs. IOL/IOH ≥ ± 20 mA. Clock Waveforms Valid in normal clock mode. In X2 mode XTAL2 must be changed to XTAL2/2. 149 4289A–8051–09/03 Figure 61. Internal Clock Signals INTERNAL CLOCK XTAL2 ALE EXTERNAL PROGRAM MEMORY FETCH PSEN P0 DATA SAMPLED FLOAT P2 (EXT) READ CYCLE RD PCL OUT (IF PROGRAM MEMORY IS EXTERNAL) PCL OUT DATA SAMPLED FLOAT INDICATES ADDRESS TRANSITIONS PCL OUT DATA SAMPLED FLOAT PCL OUT THESE SIGNALS ARE NOT ACTIVATED DURING THE EXECUTION OF A MOVX INSTRUCTION STATE4 P1 P2 STATE5 P1 P2 STATE6 P1 P2 STATE1 P1 P2 STATE2 P1 P2 STATE3 P1 P2 STATE4 P1 P2 STATE5 P1 P2 P0 DPL OR Rt OUT DATA SAMPLED FLOAT P2 WRITE CYCLE INDICATES DPH OR P2 SFR TO PCH TRANSITION WR P0 DPL OR Rt OUT DATA OUT P2 PCL OUT (EVEN IF PROGRAM MEMORY IS INTERNAL) PCL OUT (IF PROGRAM MEMORY IS EXTERNAL) INDICATES DPH OR P2 SFR TO PCH TRANSITION PORT OPERATION MOV PORT SRC MOV DEST P0 MOV DEST PORT (P1. P2. P3) (INCLUDES INTO. INT1. TO T1) SERIAL PORT SHIFT CLOCK TXD (MODE 0) P1, P2, P3 PINS SAMPLED P1, P2, P3 PINS SAMPLED OLD DATA NEW DATA P0 PINS SAMPLED P0 PINS SAMPLED RXD SAMPLED RXD SAMPLED This diagram indicates when signals are clocked internally. The time it takes the signals to propagate to the pins, however, ranges from 25 to 125 ns. This propagation delay is dependent on variables such as temperature and pin loading. Propagation also varies from output to output and component. Typically though (TA = 25°C fully loaded) RD and WR propagation delays are approximately 50 ns. The other signals are typically 85 ns. Propagation delays are incorporated in the AC specifications. 150 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Ordering Information Table 106. Possible Order Entries Part Number AT89C51ID2-SLSIM AT89C51ID2-RLTIM 2.7V-5.5V AT89C51ID2-SMSIM(1) AT89C51ID2-RDTIM (1) Supply Voltage Temperature Range Package PLCC44 VQFP44 Packing Stick Tray Stick Tray Industrial PLCC68 VQFP64 Note: 1. For PLCC68 and VQFP64 packages, please contact Atmel sales office for availability. 151 4289A–8051–09/03 Packaging Information PLCC44 152 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 VQFP44 153 4289A–8051–09/03 VQFP64 154 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 PLCC68 155 4289A–8051–09/03 Table of Contents Features................................................................................................. 1 Description ............................................................................................ 1 Block Diagram....................................................................................... 3 SFR Mapping......................................................................................... 4 Pin Configurations.............................................................................. 10 Oscillators ........................................................................................... 15 Overview............................................................................................................. Registers............................................................................................................. Functional Block Diagram................................................................................... ............................................................................................................................ Operating Modes ................................................................................................ Design Considerations........................................................................................ Timer 0: Clock Inputs.......................................................................................... 15 15 18 18 18 20 21 Enhanced Features............................................................................. 22 X2 Feature .......................................................................................................... 22 Dual Data Pointer Register DPTR...................................................... 26 Expanded RAM (XRAM) ..................................................................... 29 Registers............................................................................................................. 31 Reset .................................................................................................... 32 Introduction ......................................................................................................... 32 Reset Input ......................................................................................................... 32 Reset Output....................................................................................................... 33 Power Monitor..................................................................................... 34 Description.......................................................................................................... 34 Timer 2 ................................................................................................. 36 Auto-Reload Mode.............................................................................................. 36 Programmable Clock-Output .............................................................................. 37 Registers............................................................................................................. 39 Programmable Counter Array PCA................................................... 41 PCA Capture Mode............................................................................................. 49 16-bit Software Timer/ Compare Mode............................................................... 49 High Speed Output Mode ................................................................................... 50 156 AT89C51ID2 4289A–8051–09/03 AT89C51ID2 Pulse Width Modulator Mode.............................................................................. 51 PCA Watchdog Timer ......................................................................................... 52 Serial I/O Port ...................................................................................... 53 Framing Error Detection ..................................................................................... Automatic Address Recognition.......................................................................... Registers............................................................................................................. Baud Rate Selection for UART for Mode 1 and 3............................................... UART Registers.................................................................................................. 53 54 56 56 59 Interrupt System ................................................................................. 64 Registers............................................................................................................. 65 Interrupt Sources and Vector Addresses............................................................ 72 Power Management ............................................................................ 73 Introduction ......................................................................................................... Idle Mode ............................................................................................................ Power-Down Mode ............................................................................................. Registers............................................................................................................. 73 73 73 76 Keyboard Interface ............................................................................. 77 Registers............................................................................................................. 78 2-wire Interface (TWI) ......................................................................... 81 Description.......................................................................................................... 83 Notes .................................................................................................................. 86 Registers............................................................................................................. 96 Serial Port Interface (SPI)................................................................... 99 Features.............................................................................................................. 99 Signal Description............................................................................................... 99 Functional Description ...................................................................................... 101 Hardware Watchdog Timer .............................................................. 108 Using the WDT ................................................................................................. 108 WDT During Power Down and Idle................................................................... 109 ONCE(TM) Mode (ON Chip Emulation) ........................................... 110 Power-off Flag................................................................................... 111 EEPROM Data Memory..................................................................... 112 Write Data......................................................................................................... 112 Read Data......................................................................................................... 114 Registers........................................................................................................... 115 157 4289A–8051–09/03 Reduced EMI Mode........................................................................... 116 Flash Memory.................................................................................... 117 Features............................................................................................................ Flash Programming and Erasure...................................................................... Flash Registers and Memory Map.................................................................... Flash Memory Status........................................................................................ Memory Organization ....................................................................................... Bootloader Architecture .................................................................................... ISP Protocol Description................................................................................... Functional Description ...................................................................................... Flow Description ............................................................................................... API Call Description.......................................................................................... 117 117 118 121 121 122 126 127 129 138 Electrical Characteristics................................................................. 140 Absolute Maximum Ratings .............................................................................. 140 DC Parameters ................................................................................................. 140 AC Parameters ................................................................................................. 142 Ordering Information........................................................................ 151 Packaging Information ..................................................................... 152 PLCC44 ............................................................................................................ VQFP44 ............................................................................................................ VQFP64 ............................................................................................................ PLCC68 ............................................................................................................ 152 153 154 155 158 AT89C51ID2 4289A–8051–09/03 Atmel Corporation 2325 Orchard Parkway San Jose, CA 95131, USA Tel: 1(408) 441-0311 Fax: 1(408) 487-2600 Atmel Operations Memory 2325 Orchard Parkway San Jose, CA 95131, USA Tel: 1(408) 441-0311 Fax: 1(408) 436-4314 RF/Automotive Theresienstrasse 2 Postfach 3535 74025 Heilbronn, Germany Tel: (49) 71-31-67-0 Fax: (49) 71-31-67-2340 1150 East Cheyenne Mtn. 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Blvd. Colorado Springs, CO 80906, USA Tel: 1(719) 576-3300 Fax: 1(719) 540-1759 Scottish Enterprise Technology Park Maxwell Building East Kilbride G75 0QR, Scotland Tel: (44) 1355-803-000 Fax: (44) 1355-242-743 Japan 9F, Tonetsu Shinkawa Bldg. 1-24-8 Shinkawa Chuo-ku, Tokyo 104-0033 Japan Tel: (81) 3-3523-3551 Fax: (81) 3-3523-7581 Literature Requests www.atmel.com/literature Disclaimer: A tmel Corporation makes no warranty for the use of its products, other than those expressly contained in the Company’s standard warranty which is detailed in Atmel’s Terms and Conditions located on the Company’s web site. The Company assumes no responsibility for any errors which may appear in this document, reserves the right to change devices or specifications detailed herein at any time without notice, and does not make any commitment to update the information contained herein. No licenses to patents or other intellectual property of Atmel are granted by the Company in connection with the sale of Atmel products, expressly or by implication. Atmel’s products are not authorized for use as critical components in life support devices or systems. © Atmel Corporation 2003 . A ll rights reserved. A tmel ® a nd combinations thereof are the trademarks of Atmel Corporation or its subsidiaries. Other terms and product names may be the trademarks of others. Printed on recycled paper. 4289A–8051–09/03