Features
• • • • • • • • • • • • • •
80C51 Core Architecture 256 Bytes of On-chip RAM 256 Bytes of On-chip XRAM 16K Bytes of On-chip Flash Memory – Data Retention: 10 Years at 85°C – Erase/Write Cycle: 100K Boot Code Section with Independent Lock Bits 2K Bytes of On-chip Flash for Bootloader In-System Programming by On-Chip Boot Program (CAN, UART) and IAP Capability 2K Bytes of On-chip EEPROM – Erase/Write Cycle: 100K 14-sources 4-level Interrupts Three 16-bit Timers/Counters Full Duplex UART Compatible 80C51 Maximum Crystal Frequency 40 MHz. In X2 Mode, 20 MHz (CPU Core, 40 MHz) Three or Four Ports: 16 or 20 Digital I/O Lines Two-channel 16-bit PCA – PWM (8-bit) – High-speed Output – Timer and Edge Capture Double Data Pointer 21-bit Watchdog Timer (7 Programmable bits) A 10-bit Resolution Analog-to-Digital Converter (ADC) with 8 Multiplexed Inputs Full CAN Controller – Fully Compliant with CAN rev.# 2.0A and 2.0B – Optimized Structure for Communication Management (Via SFR) – 4 Independent Message Objects -Each Message Object Programmable on Transmission or Reception -Individual Tag and Mask Filters up to 29-bit Identifier/Channel -8-byte Cyclic Data Register (FIFO)/Message Object -16-bit Status and Control Register/Message Object -16-bit Time-Stamping Register/Message Object -CAN Specification 2.0 Part A or 2.0 Part B Programmable for Each Message Object -Access to Message Object Control and Data Registers Via SFR -Programmable Reception Buffer Length up to 4 Message Objects -Priority Management of Reception of Hits on Several Message Objects Simultaneously (Basic CAN Feature) -Priority Management for Transmission -Message Object Overrun Interrupt – Supports -Time Triggered Communication -Autobaud and Listening Mode -Programmable Automatic Reply Mode 1-Mbit/s Maximum Transfer Rate at 8 MHz(1) Crystal Frequency In X2 Mode Readable Error Counters Programmable Link to On-chip Timer for Time Stamping and Network Synchronization Independent Baud Rate Prescaler Data, Remote, Error and Overload Frame Handling Power-saving Modes – Idle Mode – Power-down Mode Power Supply: 3 Volts to 5.5 Volts Temperature Range: Industrial (-40 ° to +85°C) Packages: SOIC28, SOIC24, PLCC28, VQFP32 1. At BRP = 1 sampling point will be fixed.
Enhanced 8-bit Microcontroller with CAN Controller and Flash
• • • •
T89C51CC02 AT89C51CC02
• • • • • • • • •
Note:
Rev. 4126J–CAN–05/06
Description
Part of the CANaryTM family of 8-bit microcontrollers dedicated to CAN network applications, the T89C51CC02 is a low-pin count 8-bit Flash microcontroller. In X2 Mode a maximum external clock rate of 20 MHz reaches a 300 ns cycle time. Besides the full CAN controller T89C51CC02 provides 16K Bytes of Flash memory including In-System Programming (ISP), 2K Bytes Boot Flash Memory, 2K Bytes EEPROM and 512 Bytes RAM. Special attention is payed to the reduction of the electro-magnetic emission of T89C51CC02.
Block Diagram
RxDC CAN CONTROLLER VAVCC VAGND T2EX RxD TxD Vcc Vss PCA ECI T2 TxDC
UART
RAM 256x8
Flash Boot EE 16K x loader PROM 8 2K x 8 2K x 8
XRAM
256 x 8
PCA
Timer 2
XTAL1 XTAL2 CPU
C51 CORE
IB-bus
Timer 0 Timer 1
INT Ctrl
Parallel I/O Ports Port 1 Port 2 Port 3 Port 4
Watch Dog
10-bit ADC
RESET
Note:
1. 8 analog Inputs/8 Digital I/O. 2. 2-bit I/O Port.
2
AT/T89C51CC02
4126J–CAN–05/06
VAREF
T0
T1
INT0
INT1
P1(1)
P2(2)
P3
P4(2)
AT/T89C51CC02
Pin Configurations
VAREF VAGND VAVCC P4.1/RxDC P4.0/TxDC P2.1 P3.7 P3.6 P3.5/T1 P3.4/T0 P3.3/INT1 P3.2/INT0 P3.1/TxD P3.0/RxD 1 2 3 4 5 6 7 8 9 10 11 12 13 14 28 P1.0/AN0/T2 27 P1.1/AN1/T2EX 26 P1.2/AN2/ECI 25 P1.3/AN3/CEX0 24 P1.4/AN4/CEX1 23 P1.5/AN5 22 P1.6/AN6 21 P1.7/AN7 20 P2.0 19 18 17 16 15 RESET VSS VCC XTAL1 XTAL2
SO28
VAREF VAGND VAVCC P4.1/RxDC P4.0/TxDC P3.5/T1 P3.4/T0 P3.3/INT1 P3.2/INT0 P3.1/TxD P3.0/RxD XTAL2
1 2 3 4 5 6 7 8 9 10 11 12
SO24
24 P1.0/AN0/T2 23 P1.1/AN1/T2EX 22 P1.2/AN2/ECI 21 P1.3/AN3/CEX0 20 P1.4/AN4/CEX1 19 P1.5/AN5 18 P1.6/AN6 17 P1.7/AN7 16 RESET 15 14 13 VSS VCC XTAL1
4 3 2 1 28 27 26
P4.1/RxDC
VAVCC VAGND VAREF P1.0/AN 0/T2 P1.1/AN1/T2EX P1.2/AN2/ECI
P4.0/TxDC P 2.1 P3.7 P3.6 P3.5/T1 P3.4/T0 P3.3/INT1
5 6 7 8 9 10 11
PLCC-28
25 24 23 22 21 20 19
P1.3/AN3/CEX0 P1.4/AN4/CEX1 P1.5/AN5 P1.6/AN6 P1.7/AN7 P2.0 RESET
P3.2/INT0 P3.1/TxD P3.0/RxD XTAL2 XTAL1 VCC VSS
12 13 14 15 16 17 18
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32 31 30 29 28 27 26 25
VAVCC NC VAGND VAREF P1.0/AN 0/T2 P1.1/AN1/T2EX P1.2/AN2/ECI
P4.1/RxDC
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P3.2/INT0 P3.1/TxD P3.0/RxD NC XTAL2 XTAL1 VCC VSS
9 10 11 12 13 14 15 16
P4.0/TxDC P2.1 P3.7 P3.6 P3.5/T1 P3.4/T0 NC P3.3/INT1
1 2 3 4 5 6 7 8
QFP-32
24 23 22 21 20 19 17
18
P1.3/AN3/CEX0 P1.4/AN4/CEX1 P1.5/AN5 P1.6/AN6 P1.7/AN7 P2.0 NC RESET
AT/T89C51CC02
Pin Description
Pin Name Type Description
VSS VCC VAREF VAVCC VAGND P1.0:7
GND
Circuit ground Supply Voltage Reference Voltage for ADC (input) Supply Voltage for ADC Reference Ground for ADC (internaly connected with the VSS)
I/O
Port 1: Is an 8-bit bi-directional I/O port with internal pull-ups. Port 1 pins can be used for digital input/output or as analog inputs for the Analog Digital Converter (ADC). Port 1 pins that have 1’s written to them are pulled high by the internal pull-up transistors and can be used as inputs in this state. As inputs, Port 1 pins that are being pulled low externally will be the source of current (IIL, See section ’Electrical Characteristic’) because of the internal pull-ups. Port 1 pins are assigned to be used as analog inputs via the ADCCF register (in this case the internal pull-ups are disconnected). As a secondary digital function, port 1 contains the Timer 2 external trigger and clock input; the PCA external clock input and the PCA module I/O. P1.0/AN0/T2 Analog input channel 0, External clock input for Timer/counter2. P1.1/AN1/T2EX Analog input channel 1, Trigger input for Timer/counter2. P1.2/AN2/ECI Analog input channel 2, PCA external clock input. P1.3/AN3/CEX0 Analog input channel 3, PCA module 0 Entry of input/PWM output. P1.4/AN4/CEX1 Analog input channel 4, PCA module 1 Entry of input/PWM output. P1.5/AN5 Analog input channel 5, P1.6/AN6 Analog input channel 6, P1.7/AN7 Analog input channel 7, It can drive CMOS inputs without external pull-ups. Port 2: Is an 2-bit bi-directional I/O port with internal pull-ups. Port 2 pins that have 1’s written to them are pulled high by the internal pull-ups and can be used as inputs in this state. As inputs, Port 2 pins that are being pulled low externally will be a source of current (IIL, on the datasheet) because of the internal pull-ups. In the T89C51CC02 Port 2 can sink or source 5mA. It can drive CMOS inputs without external pull-ups.
P2.0:1
I/O
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Pin Name
Type
Description
P3.0:7
I/O
Port 3: Is an 8-bit bi-directional I/O port with internal pull-ups. Port 3 pins that have 1’s written to them are pulled high by the internal pull-up transistors and can be used as inputs in this state. As inputs, Port 3 pins that are being pulled low externally will be a source of current (IIL, See section ’Electrical Characteristic’) because of the internal pull-ups. The output latch corresponding to a secondary function must be programmed to one for that function to operate (except for TxD and WR). The secondary functions are assigned to the pins of port 3 as follows: P3.0/RxD: Receiver data input (asynchronous) or data input/output (synchronous) of the serial interface P3.1/TxD: Transmitter data output (asynchronous) or clock output (synchronous) of the serial interface P3.2/INT0 : External interrupt 0 input/timer 0 gate control input P3.3/INT1 : External interrupt 1 input/timer 1 gate control input P3.4/T0: Timer 0 counter input P3.5/T1: Timer 1 counter input P3.6: Regular I/O port pin P3.7: Regular I/O port pin Port 4: Is an 2-bit bi-directional I/O port with internal pull-ups. Port 4 pins that have 1’s written to them are pulled high by the internal pull-ups and can be used as inputs in this state. As inputs, Port 4 pins that are being pulled low externally will be a source of current (IIL, on the datasheet) because of the internal pull-up transistor. The output latch corresponding to a secondary function RxDC must be programmed to one for that function to operate. The secondary functions are assigned to the two pins of port 4 as follows: P4.0/TxDC: Transmitter output of CAN controller P4.1/RxDC: Receiver input of CAN controller. It can drive CMOS inputs without external pull-ups. Reset: A high level on this pin during two machine cycles while the oscillator is running resets the device. An internal pull-down resistor to VSS permits power-on reset using only an external capacitor to VCC. XTAL1: Input of the inverting oscillator amplifier and input of the internal clock generator circuits. To drive the device from an external clock source, XTAL1 should be driven, while XTAL2 is left unconnected. To operate above a frequency of 16 MHz, a duty cycle of 50% should be maintained. XTAL2: Output from the inverting oscillator amplifier.
P4.0:1
I/O
RESET
I/O
XTAL1
I
XTAL2
O
6
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AT/T89C51CC02
I/O Configurations
Each Port SFR operates via type-D latches, as illustrated in Figure 1 for Ports 3 and 4. A CPU ’write to latch’ signal initiates transfer of internal bus data into the type-D latch. A CPU ’read latch’ signal transfers the latched Q output onto the internal bus. Similarly, a ’read pin’ signal transfers the logical level of the Port pin. Some Port data instructions activate the ’read latch’ signal while others activate the ’read pin’ signal. Latch instructions are referred to as Read-Modify-Write instructions. Each I/O line may be independently programmed as input or output. Figure 1 shows the structure of Ports, which have internal pull-ups. An external source can pull the pin low. Each Port pin can be configured either for general-purpose I/O or for its alternate input output function. To use a pin for general-purpose output, set or clear the corresponding bit in the Px register (x = 1 to 4). To use a pin for general-purpose input, set the bit in the Px register. This turns off the output FET drive. To configure a pin for its alternate function, set the bit in the Px register. When the latch is set, the ’alternate output function’ signal controls the output level (See Figure 1). The operation of Ports is discussed further in ’Quasi-Bi-directional Port Operation’ paragraph. Figure 1. Ports Structure
VCC ALTERNATE OUTPUT FUNCTION
Port Structure
INTERNAL PULL-UP (1)
READ LATCH
INTERNAL BUS WRITE TO LATCH
D LATCH CL
Q
P1.x P2.x P3.x P4.x
(1)
READ PIN
ALTERNATE INPUT FUNCTION
Note:
1. The internal pull-up can be disabled on P1 when analog function is selected.
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Read-Modify-Write Instructions
Some instructions read the latch data rather than the pin data. The latch based instructions read the data, modify the data and then rewrite the latch. These are called ’ReadModify-Write’ instructions. Below is a complete list of these special instructions (See Table 1). When the destination operand is a Port or a Port bit, these instructions read the latch rather than the pin: Table 1. R ead/Modify/Write Instructions
Instruction ANL ORL XRL JBC CPL INC DEC DJNZ MOV Px.y, C CLR Px.y SET Px.y Description Logical AND Logical OR Logical EX-OR Jump if bit = 1 and clear bit Complement bit Increment Decrement Decrement and jump if not zero Move carry bit to bit y of Port x Clear bit y of Port x Set bit y of Port x Example ANL P1, A ORL P2, A XRL P3, A JBC P1.1, LABEL CPL P3.0 INC P2 DEC P2 DJNZ P3, LABEL MOV P1.5, C CLR P2.4 SET P3.3
It is not obvious that the last three instructions in this list are Read-Modify-Write instructions. These instructions read the port (all 8 bits), modify the specifically addressed bit and write the new byte back to the latch. These Read-Modify-Write instructions are directed to the latch rather than the pin in order to avoid possible misinterpretation of voltage (and therefore, logic) levels at the pin. For example, a Port bit used to drive the base of an external bipolar transistor cannot rise above the transistor’s base-emitter junction voltage (a value lower than VIL). With a logic one written to the bit, attempts by the CPU to read the Port at the pin are misinterpreted as logic zero. A read of the latch rather than the pins returns the correct logic one value.
Quasi Bi-directional Port Operation
Port 1, Port 3 and Port 4 have fixed internal pull-ups and are referred to as ’quasi-bidirectional’ Ports. When configured as an input, the pin impedance appears as logic one and sources current in response to an external logic zero condition. Resets write logic one to all Port latches. If logical zero is subsequently written to a Port latch, it can be returned to input conditions by a logic one written to the latch.
Note: Port latch values change near the end of Read-Modify-Write insruction cycles. Output buffers (and therefore the pin state) are updated early in the instruction after Read-Modify-Write instruction cycle.
Logical zero-to-one transitions in Port 1, Port 3 and Port 4 use an additional pull-up (p1) to aid this logic transition See Figure 2. This increases switch speed. This extra pull-up sources 100 times normal internal circuit current during 2 oscillator clock periods. The internal pull-ups are field-effect transistors rather than linear resistors. Pull-ups consist of three p-channel FET (pFET) devices. A pFET is on when the gate senses logic zero and off when the gate senses logic one. pFET #1 is turned on for two oscillator periods immediately after a zero-to-one transition in the Port latch. A logic one at the Port pin turns on pFET #3 (a weak pull-up) through the inverter. This inverter and pFET pair form a latch to drive logic one. pFET #2 is a very weak pull-up switched on whenever the
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AT/T89C51CC02
associated nFET is switched off. This is traditional CMOS switch convention. Current strengths are 1/10 that of pFET #3.
Note: During Reset, pFET#1 is not avtivated. During Reset, only the weak pFET#3 pull up the pin.
Figure 2. Internal Pull-up Configurations
2 Osc. PERIODS VCC p1(1) VCC p2 VCC p3 P1.x P2.x P3.x P4.x OUTPUT DATA n
INPUT DATA READ PIN
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SFR Mapping
Tables 3 through Table 11 show the Special Function Registers (SFRs) of the T89C51CC02.
Table 2. C51 Core SFRs
Mnemonic ACC B PSW SP Add Name 7 6 5 4 3 2 1 0
E0h Accumulator F0h B Register D0h Program Status Word 81h Stack Pointer Data Pointer Low 82h byte LSB of DPTR Data Pointer High 83h byte MSB of DPTR CY AC F0 RS1 RS0 OV F1 P
DPL
DPH
Table 3. I/O Port SFRs
Mnemonic P1 P2 P3 P4 Add Name 7 6 5 4 3 2 1 0
90h Port 1 A0h Port 2 (x2) B0h Port 3 C0h Port 4 (x2)
Table 4. Timers SFRs
Mnemonic TH0 Add 8Ch Name Timer/Counter 0 High byte Timer/Counter 0 Low byte Timer/Counter 1 High byte Timer/Counter 1 Low byte Timer/Counter 2 High byte Timer/Counter 2 Low byte Timer/Counter 0 and 1 control Timer/Counter 0 and 1 Modes TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0 7 6 5 4 3 2 1 0
TL0
8Ah
TH1
8Dh
TL1
8Bh
TH2
CDh
TL2
CCh
TCON
88h
TMOD
89h
GATE1
C/T1#
M11
M01
GATE0
C/T0#
M10
M00
10
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AT/T89C51CC02
Table 4. Timers SFRs (Continued)
Mnemonic T2CON Add C8h Name Timer/Counter 2 control Timer/Counter 2 Mode 7 TF2 6 EXF2 5 RCLK 4 TCLK 3 EXEN2 2 TR2 1 C/T2# 0 CP/RL2#
T2MOD
C9h
T2OE
DCEN
RCAP2H
Timer/Counter 2 CBh Reload/Capture High byte Timer/Counter 2 CAh Reload/Capture Low byte A6h WatchDog Timer Reset WatchDog Timer Program S2 S1 S0
RCAP2L
WDTRST
WDTPRG
A7h
Table 5. Serial I/O Port SFRs
Mnemonic SCON SBUF SADEN SADDR Add Name 7 FE/SM0 6 SM1 5 SM2 4 REN 3 TB8 2 RB8 1 TI 0 RI
98h Serial Control 99h Serial Data Buffer B9h Slave Address Mask A9h Slave Address
Table 6. PCA SFRs
Mnemonic CCON Add D8h Name PCA Timer/Counter Control PCA Timer/Counter Mode PCA Timer/Counter Low byte PCA Timer/Counter High byte 7 CF 6 CR 5 4 CCF4 3 CCF3 2 CCF2 1 CCF1 0 CCF0
CMOD
D9h
CIDL
CPS1
CPS0
ECF
CL
E9h
CH
F9h
CCAPM0 CCAPM1
PCA Timer/Counter DAh Mode 0 DBh PCA Timer/Counter Mode 1 PCA Compare FAh Capture Module 0 H FBh PCA Compare Capture Module 1 H
ECOM0 ECOM1
CAPP0 CAPP1
CAPN0 CAPN1
MAT0 MAT1
TOG0 TOG1
PWM0 PWM1
ECCF0 ECCF1
CCAP0H CCAP1H
CCAP0H7 CCAP1H7
CCAP0H6 CCAP1H6
CCAP0H5 CCAP1H5
CCAP0H4 CCAP1H4
CCAP0H3 CCAP1H3
CCAP0H2 CCAP1H2
CCAP0H1 CCAP1H1
CCAP0H0 CCAP1H0
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Table 6. PCA SFRs (Continued)
Mnemonic Add Name 7 6 5 4 3 2 1 0
CCAP0L CCAP1L
PCA Compare EAh Capture Module 0 L EBh PCA Compare Capture Module 1 L
CCAP0L7 CCAP1L7
CCAP0L6 CCAP1L6
CCAP0L5 CCAP1L5
CCAP0L4 CCAP1L4
CCAP0L3 CCAP1L3
CCAP0L2 CCAP1L2
CCAP0L1 CCAP1L1
CCAP0L0 CCAP1L0
Table 7. Interrupt SFRs
Mnemonic IEN0 Add A8h Name Interrupt Enable Control 0 Interrupt Enable Control 1 Interrupt Priority Control Low 0 Interrupt Priority Control High 0 Interrupt Priority Control Low 1 Interrupt Priority Control High1 PPC PT2 PS PT1 7 EA 6 EC 5 ET2 4 ES 3 ET1 2 EX1 1 ET0 0 EX0
IEN1
E8h
ETIM
EADC
ECAN
IPL0
B8h
PX1
PT0
PX0
IPH0
B7h
PPCH
PT2H
PSH
PT1H
PX1H
PT0H
PX0H
IPL1
F8h
POVRL
PADCL
PCANL
IPH1
F7h
POVRH
PADCH
PCANH
Table 8. ADC SFRs
Mnemonic ADCON ADCF ADCLK ADDH ADDL Add Name 7 6 PSIDLE CH7 CH6 5 ADEN CH5 4 ADEOC CH4 PRS4 ADAT9 ADAT8 ADAT7 ADAT6 3 ADSST CH3 PRS3 ADAT5 2 SCH2 CH2 PRS2 ADAT4 1 SCH1 CH1 PRS1 ADAT3 ADAT1 0 SCH0 CH0 PRS0 ADAT2 ADAT0
F3h ADC Control F6h ADC Configuration F2h ADC Clock F5h ADC Data High byte F4h ADC Data Low byte
Table 9. CAN SFRs
Mnemonic CANGCON Add Name ABh CAN General Control CAN General Status CAN General Interrupt CAN bit Timing 1 CAN bit Timing 2 CAN bit Timing 3 CANIT BRP5 SJW1 PHS22 7 ABRQ 6 OVRQ TTC 5 4 SYNCTTC 3 AUT-BAUD 2 TEST ENA 1 0 GRES
CANGSTA
AAh
OVFG
TBSY
RBSY
ENFG
BOFF
ERRP
CANGIT CANBT1 CANBT2 CANBT3
9Bh B4h B5h B6h
OVRTIM BRP4 SJW0 PHS21
OVRBUF BRP3
SERG BRP2 PRS2
CERG BRP1 PRS1 PHS11
FERG BRP0 PRS0 PHS10
AERG
PHS20
PHS12
SMP
12
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Table 9. CAN SFRs (Continued)
Mnemonic
CANEN
Add Name
CFh CAN Enable Channel byte CAN General Interrupt Enable CAN Interrupt Enable Channel byte CAN Status Interrupt Channel byte CAN Timer Control CAN Timer high CAN Timer low CAN Timer Stamp high CAN Timer Stamp low CAN Timer TTC high CAN Timer TTC low CAN Transmit Error Counter CAN Receive Error Counter CAN Page CAN Status Channel CAN Control Channel CAN Message Data CAN Identifier Tag byte 1(Part A) CAN Identifier Tag byte 1(PartB) CAN Identifier Tag byte 2 (PartA) CAN Identifier Tag byte 2 (PartB)
7
6
5
4
3
ENCH3
2
ENCH2
1
ENCH1
0
ENCH0
CANGIE
C1h
ENRX
ENTX
ENERCH
ENBUF
ENERG
CANIE
C3h
IECH3
IECH2
IECH1
IECH0
CANSIT CANTCON CANTIMH CANTIML CANSTMPH
BBh A1h ADh ACh AFh
SIT3 TPRESC 7 CANTIM 15 CANTIM 7 TIMSTMP 15 TIMSTMP7 TPRESC 6 CANTIM 14 CANTIM 6 TIMSTMP 14 TIMSTMP 6 TPRESC 5 CANTIM 13 CANTIM 5 TIMSTMP 13 TIMSTMP 5 TPRESC 4 CANTIM 12 CANTIM 4 TIMSTMP 12 TIMSTMP 4 TPRESC 3 CANTIM 11 CANTIM 3 TIMSTMP 11
SIT2 TPRESC 2 CANTIM 10 CANTIM 2 TIMSTMP 10 TIMSTMP 2
SIT1 TPRESC 1 CANTIM 9 CANTIM 1 TIMSTMP 9
SIT0 TPRESC 0 CANTIM 8 CANTIM 0 TIMSTMP 8
CANSTMPL
AEh
TIMSTMP 3
TIMSTMP 1 TIMTTC 9 TIMTTC 1 TEC1
TIMSTMP 0 TIMTTC 8 TIMTTC 0 TEC0
CANTTCH
A5h
TIMTTC 15 TIMTTC 7 TEC7
TIMTTC 14 TIMTTC 6 TEC6
TIMTTC 13 TIMTTC 5 TEC5
TIMTTC 12 TIMTTC 4 TEC4
TIMTTC 11 TIMTTC 3 TEC3
TIMTTC 10 TIMTTC 2 TEC2
CANTTCL
A4h
CANTEC
9Ch
CANREC CANPAGE CANSTCH CANCONCH CANMSG
9Dh B1h B2h B3h A3h
REC7 DLCW CONCH1 MSG7
REC6 TXOK CONCH0 MSG6
REC5 CHNB1 RXOK RPLV MSG5
REC4 CHNB0 BERR IDE MSG4
REC3 AINC SERR DLC3 MSG3
REC2 INDX2 CERR DLC2 MSG2
REC1 INDX1 FERR DLC1 MSG1
REC0 INDX0 AERR DLC0 MSG0
CANIDT1
BCh
IDT10 IDT28
IDT9 IDT27
IDT8 IDT26
IDT7 IDT25
IDT6 IDT24
IDT5 IDT23
IDT4 IDT22
IDT3 IDT21
CANIDT2
BDh
IDT2 IDT20
IDT1 IDT19
IDT0 IDT18
IDT17
IDT16
IDT15
IDT14
IDT13
CANIDT3
BEh
CAN Identifier Tag byte 3(PartA) CAN Identifier Tag byte 3(PartB) CAN Identifier Tag byte 4(PartA) CAN Identifier Tag byte 4(PartB)
CAN Identifier Mask byte 1(PartA) CAN Identifier Mask byte 1(PartB)
IDT12 IDT4
IDMSK10 IDMSK28
IDT11 IDT3
IDMSK9 IDMSK27
IDT10 IDT2
IDMSK8 IDMSK26
IDT9 IDT1
IDMSK7 IDMSK25
IDT8 -
IDT7
IDT6 -
IDT5
CANIDT4
BFh
RTRTAG IDT0
IDMSK6 IDMSK24 IDMSK5 IDMSK23
RB0TAG RB1TAG
IDMSK4 IDMSK22 IDMSK3 IDMSK21
CANIDM1
C4h
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Table 9. CAN SFRs (Continued)
Mnemonic Add Name
CAN Identifier Mask byte 2(PartA) CAN Identifier Mask byte 2(PartB) CAN Identifier Mask byte 3(PartA) CAN Identifier Mask byte 3(PartB) CAN Identifier Mask byte 4(PartA) CAN Identifier Mask byte 4(PartB)
7
IDMSK2 IDMSK20
6
IDMSK1 IDMSK19
5
IDMSK0 IDMSK18
4
IDMSK17
3
IDMSK16
2
IDMSK15
1
IDMSK14
0
IDMSK13
CANIDM2
C5h
IDMSK12
IDMSK11
IDMSK10
IDMSK9
IDMSK8
IDMSK7
IDMSK6
IDMSK5
CANIDM3
C6h
IDMSK4
IDMSK3
IDMSK2
IDMSK1
RTRMSK IDMSK0 IDEMSK
CANIDM4
C7h
Table 10. Other SFRs
Mnemonic PCON AUXR1 CKCON FCON EECON Add Name 7 SMOD1 6 SMOD0 ENBOOT CANX2 FPL3 EEPL3 WDX2 FPL2 EEPL2 PCAX2 FPL1 EEPL1 SIX2 FPL0 EEPL0 5 4 POF 3 GF1 GF3 T2X2 FPS 2 GF0 0 T1X2 FMOD1 T0X2 FMOD0 EEE 1 PD 0 IDL DPS X2 FBUSY EEBUSY
87h Power Control A2h Auxiliary Register 1 8Fh Clock Control D1h Flash Control D2h EEPROM Contol
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Table 11. SFR Mapping
0/8(1) F8h IPL1 xxxx x000 B 0000 0000 IEN1 xxxx x000 ACC 0000 0000 CCON 0000 0000 PSW 0000 0000 T2CON 0000 0000 P4 xxxx xx11 IPL0 x000 0000 P3 1111 1111 IEN0 0000 0000 P2 xxxx xx11 SCON 0000 0000 P1 1111 1111 TCON 0000 0000 TMOD 0000 0000 SP 0000 0111 0/8(1) 1/9 TL0 0000 0000 DPL 0000 0000 2/A TL1 0000 0000 DPH 0000 0000 3/B 4/C 5/D 6/E TH0 0000 0000 TH1 0000 0000 CKCON 0000 0000 PCON 00x1 0000 7/F CMOD 0xxx x000 FCON 0000 0000 T2MOD xxxx xx00 CANGIE 1100 0000 SADEN 0000 0000 CANPAGE 1100 0000 SADDR 0000 0000 CANTCON 0000 0000 SBUF 0000 0000 CANSTCH xxxx xxxx CANGSTA 1010 0000 AUXR1(2) xxxx 00x0 CCAPM0 x000 0000 EECON xxxx xx00 RCAP2L 0000 0000 RCAP2H 0000 0000 CANIE 1111 0000 CANSIT xxxx 0000 CANCONCH xxxx xxxx CANGCON 0000 0000 CANMSG xxxx xxxx CANGIT 0x00 0000 TL2 0000 0000 CANIDM1 xxxx xxxx CANIDT1 xxxx xxxx CANBT1 xxxx xxxx CANTIML 0000 0000 CANTTCL 0000 0000 CANTEC 0000 0000 TH2 0000 0000 CANIDM2 xxxx xxxx CANIDT2 xxxx xxxx CANBT2 xxxx xxxx CANTIMH 0000 0000 CANTTCH 0000 0000 CANREC 0000 0000 CANIDM3 xxxx xxxx CANIDT3 xxxx xxxx CANBT3 xxxx xxxx CANSTMPL xxxx xxxx WDTRST 1111 1111 CANEN xxxx 0000 CANIDM4 xxxx xxxx CANIDT4 xxxx xxxx IPH0 x000 0000 CANSTMPH xxxx xxxx WDTPRG xxxx x000 CCAPM1 x000 0000 CL 0000 0000 1/9 CH 0000 0000 2/A CCAP0H 0000 0000 ADCLK xxx0 0000 CCAP0L 0000 0000 3/B CCAP1H 0000 0000 ADCON x000 0000 CCAP1L 0000 0000 ADDL 0000 0000 ADDH 0000 0000 ADCF 0000 0000 IPH1 xxxx x000 4/C 5/D 6/E 7/F FFh
F0h
F7h
E8h
EFh
E0h
E7h
D8h
DFh
D0h
D7h
C8h
CFh
C0h
C7h
B8h
BFh
B0h
B7h
A8h
AFh
A0h
A7h
98h
9Fh
90h
97h
88h
8Fh
80h
87h
Reserved
Notes: 1. These registers are bit-addressable. Sixteen addresses in the SFR space are both byte-addressable and bit-addressable. The bit-addressable SFRs are those whose address ends in 0 and 8. The bit addresses, in this area, are 0x80 through to 0xFF. 2. AUXR1 bit ENBOOT is initialized with the content of the BLJB bit inverted.
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Clock
The T89C51CC02 core needs only 6 clock periods per machine cycle. This feature, called “X2”, provides the following advantages: • • • • Divides frequency crystals by 2 (cheaper crystals) while keeping the same CPU power. Saves power consumption while keeping the same CPU power (oscillator power saving). Saves power consumption by dividing dynamic operating frequency by 2 in operating and idle modes. Increases CPU power by 2 while keeping the 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 the software. An extra feature is available to start after Reset in the X2 Mode. This feature can be enabled by a bit X2B in the Hardware Security Byte. This bit is described in the section ’In-System Programming’.
Description
The X2 bit in the CKCON register (See Table 12) allows switching from 12 clock cycles per instruction to 6 clock cycles and vice versa. At reset, the standard speed is activated (STD mode). Setting this bit activates the X2 feature (X2 Mode) for the CPU Clock only (See Figure 3). The Timers 0, 1 and 2, Uart, PCA, watchdog or CAN switch in X2 Mode only if the corresponding bit is cleared in the CKCON register. The clock for the whole circuit and peripheral is first divided by two before being used by the CPU core and peripherals. This allows any cyclic ratio to be accepted on the XTAL1 input. In X2 Mode, as this divider is bypassed, the signals on XTAL1 must have a cyclic ratio between 40 to 60%. Figure 3. shows the clock generation block diagram. The X2 bit is validated on the XTAL1 ÷ 2 rising edge to avoid glitches when switching from the X2 to the STD mode. Figure 4 shows the mode switching waveforms.
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Figure 3. Clock CPU Generation Diagram
X2B
Hardware Byte On RESET PCON.0
IDL
X2
CKCON.0
XTAL1
÷2
0 1
CPU Core Clock
XTAL2
CPU CLOCK
PD
PCON.1
CPU Core Clock Symbol and ADC
1 2
÷ ÷ ÷ ÷ ÷ ÷ ÷
FT0 Clock
X2
CKCON.0
CANX2
CKCON.7
WDX2
CKCON.6
PCAX2
CKCON.5
SIX2
CKCON.4
T2X2
CKCON.3
T1X2
CKCON.2
T0X2
CKCON.1
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0 1 0 2
FT1 Clock
1 0
2
FT2 Clock FUart Clock
1 0
2
1 0
2
FPca Clock FWd Clock
1 0
2
1 0
2
FCan Clock
PERIPH CLOCK
Peripheral Clock Symbol
17
Figure 4. Mode Switching Waveforms(1)
XTAL1
XTAL2
X2 bit
CPU clock STD Mode X2 Mode STD Mode
Note:
1. In order to prevent any incorrect operation while operating in the X2 Mode, users must be aware that all peripherals using the clock frequency as a time reference (UART, timers...) will have their time reference divided by 2. For example, a free running timer generating an interrupt every 20 ms will then generate an interrupt every 10 ms. A UART with a 4800 baud rate will have a 9600 baud rate.
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Register
Table 12. CKCON Register CKCON (S:8Fh) Clock Control Register
7 CANX2 Bit Number 6 WDX2 5 PCAX2 4 SIX2 3 T2X2 2 T1X2 1 T0X2 0 X2
Bit Mnemonic Description CAN Clock (1) Clear to select 6 clock periods per peripheral clock cycle. Set to select 12 clock periods per peripheral clock cycle. Watchdog Clock (1) Clear to select 6 clock periods per peripheral clock cycle. Set to select 12 clock periods per peripheral clock cycle. Programmable Counter Array Clock (1) Clear 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) (1) Clear to select 6 clock periods per peripheral clock cycle. Set to select 12 clock periods per peripheral clock cycle. Timer 2 Clock (1) Clear to select 6 clock periods per peripheral clock cycle. Set to select 12 clock periods per peripheral clock cycle. Timer 1 Clock (1) Clear to select 6 clock periods per peripheral clock cycle. Set to select 12 clock periods per peripheral clock cycle. Timer 0 Clock (1) Clear to select 6 clock periods per peripheral clock cycle. Set to select 12 clock periods per peripheral clock cycle. CPU Clock Clear to select 12 clock periods per machine cycle (STD mode) for CPU and all the peripherals. Set to select 6 clock periods per machine cycle (X2 Mode) and to enable the individual peripherals ’X2’ bits.
7
CANX2
6
WDX2
5
PCAX2
4
SIX2
3
T2X2
2
T1X2
1
T0X2
0
X2
Note:
1. This control bit is validated when the CPU clock bit X2 is set; when X2 is low, this bit has no effect.
Reset Value = 0000 0000b
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Power Management
Two power reduction modes are implemented in the A/T89C51CC02: 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 “Clock”. In order to start-up (cold reset) or to restart (warm reset) properly the microcontroller, a high level has to be applied on the RST pin. A bad level leads to a wrong initialisation of the internal registers like SFRs, PC, etc. and to unpredictable behavior of the microcontroller. A warm reset can be applied either directly on the RST pin or indirectly by an internal reset source such as a watchdog, PCA, timer, etc. Two conditions are required before enabling a CPU start-up: • • VDD must reach the specified VDD range, The level on xtal1 input must be outside the specification (VIH, VIL).
Reset Pin
At Power-up (cold reset)
If one of these two conditions are not met, the microcontroller does not start correctly and can execute an instruction fetch from anywhere in the program space. An active level applied on the RST pin must be maintained until both of the above conditions are met. A reset is active when the level VIH1 is reached and when the pulse width covers the period of time where VDD and the oscillator are not stabilized. Two parameters have to be taken into account to determine the reset pulse width: • • VDD rise time (vddrst), Oscillator startup time (oscrst).
To determine the capacitor the highest value of these two parameters has to be chosen. The reset circuitry is shown in Figure 5. Figure 5. Reset Circuitry
VDD Crst RST pin Internal reset Rrst Reset input circuitry
0
Table 13 and Table 14 give some typical examples for three values of VDD rise times, two values of oscillator start-up time and two pull-down resistor values. Table 13. Minimum Reset Capacitor for a 50K Pull-down Resistor
oscrst/vddrst 5ms 20ms 1ms 820nF 2.7µF 10ms 1.2µF 3.9µF 100ms 12µF 12µF
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Table 14. Minimum Reset Capacitor for a 15k Pull-down Resistor
oscrst/vddrst 5ms 20ms 1ms 2.7µF 10µF 10ms 4.7µF 15µF 100ms 47µF 47µF
Note:
These values assume VDD starts from 0v to the nominal value. If the time between two on/off sequences is too fast, the power-supply decoupling capacitors may not be fully discharged, leading to a bad reset sequence.
During a Normal Operation (Warm Reset) Watchdog Reset
Reset pin must be maintained for at least 2 machine cycles (24 oscillator clock periods) to apply a reset sequence during normal operation. The number of clock periods is mode independent (X2 or X1). A 1K resistor must be added in series with the capacitor to allow the use of watchdog reset pulse output on the RST pin or when an external power-supply supervisor is used. Figure 6 shows the reset circuitry when a capacitor is used. Figure 6. Reset Circuitry for a Watchdog Configuration
VDD Crst 1k RST pin Internal reset Rrst Reset input circuitry watchdog
To other on-board circuitry
Figure 7 shows the reset circuitry when an external reset circuit is used. Figure 7. Reset Circuitry Example Using an External Reset Circuit
VDD watchdog External reset circuit RST Internal reset Rrst Reset input circuitry 1k RST pin
To other on-board circuitry
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Reset Recommendation to Prevent Flash Corruption
When a Flash program memory is embedded on-chip, it is strongly recommended to use an external reset chip (brown out device) to apply a reset (Figure 7). It prevents system malfunction during periods of insufficient power-supply voltage (power-supply failure, power supply switched off, etc.).
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 15. To e n ter Id le mo de , s e t th e IDL b it in PC O N re g is te r ( Se e Tab le 16 ) . Th e A/T89C51CC02 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 A/T89C51CC02 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. 2. Generate a reset. 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 A/T89C51CC02 and vectors the CPU to address C:0000h.
Notes: 1. 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. If Idle mode is invoked by ADC Idle, the ADC conversion completion will exit Idle.
Power-down Mode
The Power-down mode places the A/T89C51CC02 in a very low power state. Powerdown 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 SFRs and RAM contents are preserved. The status of the Port pins during Power-down mode is detailed in Table 15. To enter Power-down mode, set PD bit in PCON register. The A/T89C51CC02 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.
Entering Power-down Mode
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Exiting Power-down Mode
Note: If VDD was reduced during the Power-down mode, do not exit Power-down mode until VDD is restored to the normal operating level.
There are two ways to exit the Power-down mode: 1. Generate an enabled external interrupt. – The A/T89C51CC02 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 8). 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.
1. 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. 2. Exit from power-down by external interrupt does not affect the SFRs nor the internal RAM content.
Notes:
Figure 8. 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 A/T89C51CC02 and vectors the CPU to address 0000h.
1. 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 the Power-down mode should not write to a Port pin or to the external RAM. 2. Exit from power-down by reset redefines all the SFRs, but does not affect the internal RAM content.
Notes:
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Table 15. Pin Conditions in Special Operating Modes
Mode Reset Idle (internal code) Idle (external code) PowerDown(inter nal code) PowerDown (external code) Port 1 High Port 2 High Port 3 High Port 4 High
Data
Data
Data
Data
Data
Data
Data
Data
Data
Data
Data
Data
Data
Data
Data
Data
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Registers
Table 16. PCON Register PCON (S:87h) Power Control Register
7 SMOD1 Bit Number 7 6 SMOD0 5 4 POF 3 GF1 2 GF0 1 PD 0 IDL
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 Clear 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 Clear 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 Clear by hardware when interrupt or reset occurs. Set to enter idle mode.
6
SMOD0
5
-
4
POF
3
GF1
2
GF0
1
PD
0
IDL
Reset Value = 00X1 0000b Not bit addressable
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Data Memory
The T89C51CC02 provides data memory access in two different spaces: The internal space mapped in three separate segments: • • • The lower 128 Bytes RAM segment. The upper 128 Bytes RAM segment. The expanded 256 Bytes RAM segment (XRAM).
A fourth internal segment is available but dedicated to Special Function Registers, SFRs, (addresses 80h to FFh) accessible by direct addressing mode. Figure 9 shows the internal data memory spaces organization. Figure 9. Internal memory - RAM
FFh FFh Upper 128 Bytes Internal RAM Indirect Addressing 80h 7Fh 80h Lower 128 Bytes Internal RAM Direct or Indirect Addressing FFh Special Function Registers Direct Addressing
256 Bytes Internal XRAM
00h
00h
Internal Space
Lower 128 Bytes RAM The lower 128 Bytes of RAM (See Figure 10) are accessible from address 00h to 7Fh using direct or indirect addressing modes. The lowest 32 Bytes are grouped into 4 banks of 8 registers (R0 to R7). Two bits RS0 and RS1 in PSW register (See Table 18) select which bank is in use according to Table 17. This allows more efficient use of code space, since register instructions are shorter than instructions that use direct addressing, and can be used for context switching in interrupt service routines. Table 17. Register Bank Selection
RS1 0 0 1 1 RS0 0 1 0 1 Description Register bank 0 from 00h to 07h Register bank 0 from 08h to 0Fh Register bank 0 from 10h to 17h Register bank 0 from 18h to 1Fh
The next 16 Bytes above the register banks form a block of bit-addressable memory space. The C51 instruction set includes a wide selection of singlebit instructions, and the 128 bits in this area can be directly addressed by these instructions. The bit addresses in this area are 00h to 7Fh.
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Figure 10. Lower 128 Bytes Internal RAM Organization
7Fh
30h 2Fh 20h 18h 10h 08h 00h 1Fh 17h 0Fh 07h 4 Banks of 8 Registers R0-R7 bit-Addressable Space (bit Addresses 0-7Fh)
Upper 128 Bytes RAM
The upper 128 Bytes of RAM are accessible from address 80h to FFh using only indirect addressing mode. The on-chip 256 Bytes of expanded RAM (XRAM) are accessible from address 0000h to 00FFh using indirect addressing mode through MOVX instructions. In this address range.
Note: Lower 128 Bytes RAM, Upper 128 Bytes RAM, and expanded RAM are made of volatile memory cells. This means that the RAM content is indeterminate after power-up and must then be initialized properly.
Expanded RAM
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Dual Data Pointer
Description The T89C51CC02 implements a second data pointer for speeding up code execution and reducing code size in case of intensive usage of external memory accesses. DPTR0 and DPTR1 are Seen by the CPU as DPTR and are accessed using the SFR addresses 83h and 84h that are the DPH and DPL addresses. The DPS bit in AUXR1 register (See Figure 19) is used to select whether DPTR is the data pointer 0 or the data pointer 1 (See Figure 11). Figure 11. Dual Data Pointer Implementation
DPL0 DPL1
DPTR0 DPTR1 0
DPL
1
DPS DPH0 DPH1
0
AUXR1.0
DPTR
DPH
1
Application
Software can take advantage of the additional data pointers to both increase speed and reduce code size, for example, block operations (copy, compare…) are well served by using one data pointer as a “source” pointer and the other one as a “destination” pointer. Hereafter is an example of block move implementation using the two pointers and coded in assembler. The latest C compiler takes also advantage of this feature by providing enhanced algorithm libraries. The INC instruction is a short (2 Bytes) and fast (6 machine cycle) way to manipulate the DPS bit in the AUXR1 register. 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.
; ASCII block move using dual data pointers ; Modifies DPTR0, DPTR1, A and PSW ; Ends when encountering NULL character ; Note: DPS exits opposite to the entry state unless an extra INC AUXR1 is added AUXR1EQU0A2h move:movDPTR,#SOURCE ; address of SOURCE incAUXR1 ; switch data pointers movDPTR,#DEST ; address of DEST mv_loop:incAUXR1; switch data pointers movxA,@DPTR; get a byte from SOURCE incDPTR; increment SOURCE address incAUXR1; switch data pointers movx@DPTR,A; write the byte to DEST incDPTR; increment DEST address jnzmv_loop; check for NULL terminator end_move:
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Registers
Table 18. PSW Register PSW (S:D0h) Program Status Word Register
7 CY Bit Number 7 6 AC 5 F0 4 RS1 3 RS0 2 OV 1 F1 0 P
Bit Mnemonic Description CY Carry Flag Carry out from bit 1 of ALU operands. Auxiliary Carry Flag Carry out from bit 1 of addition operands. User Definable Flag 0 Register Bank Select bits Refer to Table 17 for bits description. Overflow Flag Overflow set by arithmetic operations. User Definable Flag 1 Parity bit Set when ACC contains an odd number of 1’s. Cleared when ACC contains an even number of 1’s.
6 5 4-3
AC F0 RS1:0
2 1
OV F1
0
P
Reset Value = 0000 0000b
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Table 19. AUXR1 Register AUXR1 (S:A2h) Auxiliary Control Register 1
7 Bit Number 7-6 6 Bit Mnemonic 5 ENBOOT 4 3 GF3 2 0 1 0 DPS
Description Reserved The value read from these bits is indeterminate. Do not set these bits.
5
Enable Boot Flash ENBOOT(1) Set this bit to map the boot Flash between F800h -FFFFh Clear this bit to disable boot Flash. GF3 Reserved The value read from this bit is indeterminate. Do not set this bit. General Purpose Flag 3 Always Zero This bit is stuck to logic 0 to allow INC AUXR1 instruction without affecting GF3 flag. Reserved for Data Pointer Extension Data Pointer Select bit Set to select second dual data pointer: DPTR1. Clear to select first dual data pointer: DPTR0.
4 3
2
0
1
-
0
DPS
Reset Value = XXXX 00X0b
Note: 1. ENBOOT is initialized with the invert BLJB at reset. See In-System Programming section.
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EEPROM Data Memory
The 2K bytes on-chip EEPROM memory block is located at addresses 0000h to 07FFh of the XRAM/XRAM memory space and is selected by setting control bits in the EECON register. A read in the EEPROM memory is done with a MOVX instruction. A physical write in the EEPROM memory is done in two steps: write data in the column latches and transfer of all data latches into an EEPROM memory row (programming). The number of data written on the page may vary from 1 up to 128 Bytes (the page size). When programming, only the data written in the column latch is programmed and a ninth bit is used to obtain this feature. This provides the capability to program the whole memory by Bytes, by page or by a number of Bytes in a page. Indeed, each ninth bit is set when the writing the corresponding byte in a row and all these ninth bits are reset after the writing of the complete EEPROM row.
Write Data in the Column Latches
Data is written by byte to the column latches as for an external RAM memory. Out of the 11 address bits of the data pointer, the 4 MSBs are used for page selection (row) and 7 are used for byte selection. Between two EEPROM programming sessions, all the addresses in the column latches must stay on the same page, meaning that the 4 MSB must no be changed. The following procedure is used to write to the column latches: • • • • • • • Save and disable interrupt Set bit EEE of EECON register Load DPTR with the address to write Store A register with the data to be written Execute a MOVX @DPTR, A If needed loop the three last instructions until the end of a 128 Bytes page Restore interrupt
The last page address used when loading the column latch is the one used to select the page programming address.
Note:
Programming
The EEPROM programming consists of the following actions: • Write one or more Bytes of one page in the column latches. Normally, all Bytes must belong to the same page; if not, the last page address will be latched and the others discarded. Launch programming by writing the control sequence (50h followed by A0h) to the EECON register. EEBUSY flag in EECON is then set by hardware to indicate that programming is in progress and that the EEPROM segment is not available for reading. The end of programming is indicated by a hardware clear of the EEBUSY flag.
The sequence 5xh and Axh must be executed without instructions between then otherwise the programming is aborted.
• • •
Note:
Read Data
The following procedure is used to read the data stored in the EEPROM memory: • • • • • Save and disable interrupt Set bit EEE of EECON register Load DPTR with the address to read Execute a MOVX A, @DPTR Restore interrupt
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Examples
;*F************************************************************************* ;* NAME: api_rd_eeprom_byte ;* DPTR contain address to read. ;* Acc contain the reading value ;* NOTE: before execute this function, be sure the EEPROM is not BUSY ;*************************************************************************** api_rd_eeprom_byte: ; Save and clear EA MOV MOV ret EECON, #02h; map EEPROM in XRAM space EECON, #00h; unmap EEPROM
MOVX A, @DPTR ; Restore EA
;*F************************************************************************* ;* NAME: api_ld_eeprom_cl ;* DPTR contain address to load ;* Acc contain value to load ;* NOTE: in this example we load only 1 byte, but it is possible upto ;* 128 Bytes. ;* before execute this function, be sure the EEPROM is not BUSY ;*************************************************************************** api_ld_eeprom_cl: ; Save and clear EA MOV EECON, #02h ; map EEPROM in XRAM space MOVX @DPTR, A MOVEECON, #00h; unmap EEPROM ; Restore EA ret ;*F************************************************************************* ;* NAME: api_wr_eeprom ;* NOTE: before execute this function, be sure the EEPROM is not BUSY ;*************************************************************************** api_wr_eeprom: ; Save and clear EA MOV MOV ret EECON, #050h EECON, #0A0h
; Restore EA
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Registers
Table 20. EECON Register EECON (S:0D2h) EEPROM Control Register
7 EEPL3 6 EEPL2 Bit Mnemonic EEPL3-0 5 EEPL1 4 EEPL0 3 2 1 EEE 0 EEBUSY
Bit Number 7-4
Description Programming Launch Command bits Write 5Xh followed by AXh to EEPL to launch the programming. 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 EEPROM Space bit Set to map the EEPROM space during MOVX instructions (Write in the column latches) Clear to map the XRAM space during MOVX. Programming Busy Flag Set by hardware when programming is in progress. Cleared by hardware when programming is done. Can not be set or cleared by software.
3
-
2
-
1
EEE
0
EEBUSY
Reset Value = XXXX XX00b Not bit addressable
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Program/Code Memory
The T89C51CC02 implement 16K Bytes of on-chip program/code memory. The Flash memory increases EPROM and ROM functionality by in-circuit electrical erasure and programming. Thanks to the internal charge pump, the high voltage needed for programming or erasing Flash cells is generated on-chip using the standard V DD voltage. Thus, the Flash memory can be programmed using only one voltage and allows InSystem Programming (ISP). Hardware programming mode is also available using specific programming tool. Figure 12. Program/Code Memory Organization
3FFFh 16K Bytes Internal Flash
0000h
Flash Memory Architecture
T89C51CC02 features two on-chip Flash memories: • Flash memory FM0: containing 16K Bytes of program memory (user space) organized into 128 bytes pages, Flash memory FM1: 2K Bytes for boot loader and Application Programming Interfaces (API).
•
The FM0 can be program by both parallel programming and Serial ISP whereas FM1 supports only parallel programming by programmers. The ISP mode is detailed in the ’In-System Programming’ section. All Read/Write access operations on Flash memory by user application are managed by a set of API described in the ’In-System Programming’ section. Figure 13. Flash Memory Architecture
2K Bytes Flash Memory Boot Space FM1
FFFFh
Hardware Security (1 byte) Extra Row (128 Bytes) Column Latches (128 Bytes)
F800h
3FFFh
16K Bytes Flash Memory User Space FM0
FM1 mapped between F800h and FFFFh when bit ENBOOT is set in AUXR1 register
0000h
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FM0 Memory Architecture The Flash memory is made up of 4 blocks (See Figure 13): 1. The memory array (user space) 16K Bytes 2. The Extra Row 3. The Hardware security bits 4. The column latch registers User Space This space is composed of a 16K Bytes Flash memory organized in 128 pages of 128 Bytes. It contains the user’s application code. This row is a part of FM0 and has a size of 128 Bytes. The extra row may contain information for boot loader usage. The Hardware security Byte space is a part of FM0 and has a size of 1 byte. The 4 MSB can be read/written by software, the 4 LSB can only be read by software and written by hardware in parallel mode. The column latches, also part of FM0, have a size of full page (128 Bytes). The column latches are the entrance buffers of the three previous memory locations (user array, XROW and Hardware security byte). The FM0 memory can be programmed as describe on Table 21. Programming FM0 from FM0 is impossible. The FM1 memory can be program only by parallel programming. Table 21 show all software Flash access allowed. Table 21. Cross Flash Memory Access
Action Code executing from Read FM0 (user Flash) Load column latch Write Read FM1 (boot Flash) Load column latch Write FM0 (user Flash) ok ok ok ok ok FM1 (boot Flash) ok -
Extra Row (XRow)
Hardware Security Byte
Column Latches
Cross Flash Memory Access Description
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Overview of FM0 Operations
The CPU interfaces the Flash memory through the FCON register and AUXR1 register. These registers are used to: • • • Map the memory spaces in the adressable space Launch the programming of the memory spaces Get the status of the Flash memory (busy/not busy)
Mapping of the Memory Space By default, the user space is accessed by MOVC instruction for read only. The column latches space is made accessible by setting the FPS bit in FCON register. Writing is possible from 0000h to 3FFFh, address bits 6 to 0 are used to select an address within a page while bits 14 to 7 are used to select the programming address of the page. Setting FPS bit takes precedence on the EEE bit in EECON register. The other memory spaces (user, extra row, hardware security) are made accessible in the code segment by programming bits FMOD0 and FMOD1 in FCON register in accordance with Table 22. A MOVC instruction is then used for reading these spaces. Table 22. FM0 blocks Select bits
FMOD1 0 0 1 1 FMOD0 0 1 0 1 FM0 Adressable Space User (0000h-3FFFh) Extra Row(FF80h-FFFFh) Hardware Security Byte (0000h) Reserved
Launching Programming
FPL3:0 bits in FCON register are used to secure the launch of programming. A specific sequence must be written in these bits to unlock the write protection and to launch the programming. This sequence is 5xh followed by Axh. Table 23 summarizes the memory spaces to program according to FMOD1:0 bits. Table 23. Programming Spaces
Write to FCON FPL3:0 5 User A 5 Extra Row A Hardware Security Byte Reserved A x 1 1 No action 5 A 5 x x x x 0 1 1 1 1 0 0 1 x x 0 0 0 1 FPS x FMOD1 0 FMOD0 0 Operation No action Write the column latches in user space No action Write the column latches in extra row space No action Write the fuse bits space No action
Note:
The sequence 5xh and Axh must be executing without instructions between them otherwise the programming is aborted. Interrupts that may occur during programming time must be disabled to avoid any spurious exit of the programming mode.
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Status of the Flash Memory The bit FBUSY in FCON register is used to indicate the status of programming. FBUSY is set when programming is in progress. Selecting FM1 Loading the Column Latches The bit ENBOOT in AUXR1 register is used to map FM1 from F800h to FFFFh. Any number of data from 1 byte to 128 Bytes can be loaded in the column latches. This provides the capability to program the whole memory by byte, by page or by any number of Bytes in a page. When programming is launched, an automatic erase of the locations loaded in the column latches is first performed, then programming is effectively done. Thus no page or block erase is needed and only the loaded data are programmed in the corresponding page. The following procedure is used to load the column latches and is summarized in Figure 14: • • • • • • Save then disable interrupt and map the column latch space by setting FPS bit. Load the DPTR with the address to load. Load Accumulator register with the data to load. Execute the MOVX @DPTR, A instruction. If needed loop the three last instructions until the page is completely loaded. unmap the column latch and Restore Interrupt
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Figure 14. Column Latches Loading Procedure(1)
Column Latches Loading
Save & Disable IT EA = 0
Column Latches Mapping FCON = 08h (FPS = 1)
Data Load DPTR = Address ACC = Data Exec: MOVX @DPTR, A
Last Byte to load?
Data Memory Mapping FCON = 00h (FPS = 0)
Restore IT
Note:
1. The last page address used when loading the column latch is the one used to select the page programming address.
Programming the Flash Spaces User The following procedure is used to program the User space and is summarized in Figure 15: • • • Load up to one page of data in the column latches from address 0000h to 3FFFh. Save then disable the interrupts. Launch the programming by writing the data sequence 50h followed by A0h in FCON register.This step must be executed from FM1. The end of the programming indicated by the FBUSY flag cleared. Restore the interrupts.
• Extra Row
The following procedure is used to program the Extra Row space and is summarized in Figure 15: • • • Load data in the column latches from address FF80h to FFFFh. Save then disable the interrupts. Launch the programming by writing the data sequence 52h followed by A2h in FCON register. This step of the procedure must be executed from FM1. The end of the programming indicated by the FBUSY flag cleared. Restore the interrupts.
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Figure 15. Flash and Extra row Programming Procedure
Flash Spaces Programming
Column Latches Loading See Figure 14
Save & Disable IT EA = 0
Launch Programming FCON = 5xh FCON = Axh
FBusy Cleared?
Clear Mode FCON = 00h
End Programming Restore IT
Hardware Security Byte
The following procedure is used to program the Hardware Security Byte space and is summarized in Figure 16:
• • • • • • Set FPS and map Hardware byte (FCON = 0x0C) Save then disable the interrupts. Load DPTR at address 0000h. Load Accumulator register with the data to load. Execute the MOVX @DPTR, A instruction. Launch the programming by writing the data sequence 54h followed by A4h in FCON register. This step of the procedure must be executed from FM1. The end of the programming indicated by the FBusy flag cleared. Restore the interrupts
•
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Figure 16. Hardware Programming Procedure
Flash Spaces Programming
Save & Disable IT EA = 0 Save & Disable IT EA = 0 Launch Programming FCON = 54h FCON = A4h
FCON = 0Ch
Data Load DPTR = 00h ACC = Data Exec: MOVX @DPTR, A
FBusy Cleared?
End Loading Restore IT
Clear Mode FCON = 00h
End Programming RestoreIT
Reading the Flash Spaces User The following procedure is used to read the User space: • Read one byte in Accumulator by executing MOVC A,@A+DPTR with A+DPTR is the address of the code byte to read.
FCON must be cleared (00h) when not used.
Note:
Extra Row
The following procedure is used to read the Extra Row space and is summarized in Figure 17: • • • Map the Extra Row space by writing 02h in FCON register. Read one byte in Accumulator by executing MOVC A,@A+DPTR with A= 0 & DPTR= FF80h to FFFFh. Clear FCON to unmap the Extra Row.
Hardware Security Byte
The following procedure is used to read the Hardware Security Byte and is summarized in Figure 17:
• • • Map the Hardware Security space by writing 04h in FCON register. Read the byte in Accumulator by executing MOVC A,@A+DPTR with A= 0 & DPTR= 0000h. Clear FCON to unmap the Hardware Security Byte.
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Figure 17. Reading Procedure
Flash Spaces Reading
Flash Spaces Mapping FCON = 00000aa0b
Data Read DPTR = Address ACC= 0 Exec: MOVC A, @A+DPTR
Clear Mode FCON = 00h
Note:
aa = 10 for the Hardware Security Byte.
Flash Protection from Parallel Programming
The three lock bits in Hardware Security Byte (See ’In-System Programming’ section) are programmed according to Table 24 provide different level of protection for the onchip code and data located in FM0 and FM1. The only way to write this bits are the parallel mode. They are set by default to level 3. Table 24. Program Lock bit
Program Lock bits Security Level 1 2 3 4 LB0 U P U U LB1 U U P U LB2 U U U P
Protection Description No program lock features enabled. Parallel programming of the Flash is disabled. Same as 2, also verify through parallel programming interface is disabled. This is the factory defaul programming. Same as 3
Note:
1. Program Lock bits U: unprogrammed P: programmed
WARNING: Security level 2, 3 and 4 should only be programmed after Flash and Core verification. Preventing Flash Corruption See Section “Power Management”.
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Registers
Table 25. FCON Register FCON Register FCON (S:D1h) Flash Control Register
7 FPL3 Bit Number 6 FPL2 5 FPL1 4 FPL0 3 FPS 2 FMOD1 1 FMOD0 0 FBUSY
Bit Mnemonic Description Programming Launch Command bits Write 5Xh followed by AXh to launch the programming according to FMOD1:0. (See Table 23.) Flash Map Program Space Set to map the column latch space in the data memory space. Clear to re-map the data memory space. Flash Mode See Table 22 or Table 23. Flash Busy Set by hardware when programming is in progress. Clear by hardware when programming is done. Can not be changed by software.
7-4
FPL3:0
3
FPS
2-1
FMOD1:0
0
FBUSY
Reset Value = 0000 0000b
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Operation Cross Memory Access
Space addressable in read and write are: • • • • • • • • RAM ERAM (Expanded RAM access by movx) EEPROM DATA FM0 ( user flash ) Hardware byte XROW Boot Flash Flash Column latch
The table below provides the different kind of memory which can be accessed from different code location. Table 26. Cross Memory Access
Hardware Action Read boot FLASH Write Read FM0 Write OK (idle) OK (1) -OK OK OK(1) OK OK(1) OK OK(1) -OK OK(1) RAM ERAM Boot FLASH OK FM0 OK E² Data OK Byte OK XROW -
Note:
1. RWW: Read While Write
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Sharing Instructions
Table 27. Instructions shared
Action Read Write RAM MOV MOV ERAM MOVX MOVX EEPROM DATA MOVX MOVX Boot FLASH MOVC FM0 MOVC by cl Hardware Byte MOVC by cl XROW MOVC by cl
Note:
by cl : using Column Latch
Table 28. Read MOVX A, @DPTR
EEE bit in EECON Register 0 0 1 1 FPS in FCON Register 0 1 0 1 ENBOOT X X X X OK ERAM OK OK OK EEPROM DATA Flash Column Latch
Table 29. Write MOVX @DPTR,A
EEE bit in EECON Register 0 0 1 1 FPS bit in FCON Register 0 1 0 1 ENBOOT X X X X OK OK ERAM OK OK EEPROM Data Flash Column Latch
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Table 30. Read MOVC A, @DPTR
FCON Register Code Execution FMOD1 FMOD0 FPS ENBOOT 0 0 0 X 1 F800h to FFFFh 0 From FM0 1 0 X X 0 1 1 X 1 F800h to FFFFh 0000h to 3FFF 1 0 0 0 1 0 From FM1 (ENBOOT =1 0 1 X 0 1 1 0 X 0 1 1 1 X 0 000h to 3FFFh NA OK X NA 1 X 0000h to 007h See
(2)
Hardware DPTR 0000h to 3FFFh 0000h to 3FFFh FM1 FM0 OK OK Do not use this configuration OK OK OK OK Do not use this configuration OK OK NA OK NA OK NA OK XROW Byte
1
X
X
0000 to 007Fh See (1) X 000h to 3FFFh 0000h to 3FFFh
F800h to FFFFh 0 1 X X
1. For DPTR higher than 007Fh only lowest 7 bits are decoded, thus the behavior is the same as for addresses from 0000h to 007Fh 2. For DPTR higher than 007Fh only lowest 7 bits are decoded, thus the behavior is the same as for addresses from 0000h to 007Fh
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In-System Programming (ISP)
With the implementation of the User Space (FM0) and the Boot Space (FM1) in Flash technology the T89C51CC02 allows the system engineer the development of applications with a very high level of flexibility. This flexibility is based on the possibility to alter the customer program at any stages of a product’s life: • Before mounting the chip on the PCB, FM0 flash can be programmed with the application code. FM1 is always preprogrammed by Atmel with a bootloader (chip can be ordered with CAN bootloader or UART bootloader).(1) Once the chip is mounted on the PCB, it can be programmed by serial mode via the CAN bus or UART.
1. The user can also program his own bootloader in FM1.
•
Note:
This ISP allows code modification over the total lifetime of the product. Besides the default Bootloaders Atmel provide customers all the needed ApplicationProgramming-Interfaces (API) which are needed for the ISP. The API are located in the Boot memory. This allow the customer to have a full use of the 16-Kbyte user memory.
Flash Programming and Erasure
There are three methods for programming the Flash memory: • The Atmel bootloader located in FM1 is activated by the application. Low level API routines (located in FM1)will be used to program FM0. The interface used for serial downloading to FM0 is the UART or the CAN. API can be called also by user’s bootloader located in FM0 at [SBV]00h. A further method exist in activating the Atmel boot loader by hardware activation. See the Section “Hardware Security Byte”. The FM0 can be programmed also by the parallel mode using a programmer.
• •
Figure 18. Flash Memory Mapping FFFFh
2K Bytes IAP Bootloader FM1
F800h
3FFFh
Custom Bootloader [SBV]00h
16K Bytes
FM1 Mapped between F800h and FFFFh when API Called
Flash Memory FM0
0000h
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Boot Process
Software Boot Process Example Many algorithms can be used for the software boot process. Below are descriptions of the different flags and Bytes. Boot Loader Jump bit (BLJB): - This bit indicates if on RESET the user wants to jump to this application at address @0000h on FM0 or execute the boot loader at address @F800h on FM1. - BLJB = 0 (i.e. bootloader FM1 executed after a reset) is the default Atmel factory programming. -To read or modify this bit, the APIs are used. Boot Vector Address (SBV): - This byte contains the MSB of the user boot loader address in FM0. - The default value of SBV is FCh (no user boot loader in FM0). - To read or modify this byte, the APIs are used. Extra Byte (EB) & Boot Status Byte (BSB): - These Bytes are reserved for customer use. - To read or modify these Bytes, the APIs are used. Figure 19. Hardware Boot Process Algorithm
RESET
bit ENBOOT in AUXR1 Register Is Initialized with BLJB Inverted.
Example, if BLJB=0, ENBOOT
Hardware
ENBOOT = 0 PC = 0000h
BLJB == 0 ?
is set (=1) during reset, thus the bootloader is executed after the reset.
ENBOOT = 1 PC = F800h
Software
Application in FM0
Bootloader in FM1
ApplicationProgramming-Interface
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 by functions. All these APIs are described in detail in the following documents on the Atmel web site. – – Datasheet Bootloader CAN T89C51CC02. Datasheet Bootloader UART T89C51CC02.
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XROW Bytes
The EXTRA ROW (XROW) includes 128 bytes. Some of these bytes are used for specific purpose in conjonction with the bootloader. Table 31. XROW Mapping
Description Copy of the Manufacturer Code Copy of the Device ID#1: Family code Copy of the Device ID#2: Memories size and type Copy of the Device ID#3: Name and Revision Default Value 58h D7h BBh FFh Address 30h 31h 60h 61h
Hardware Conditions
It is possible to force the controller to execute the bootloader after a Reset with hardware conditions. During the first programming, the user can define a configuration on Port1 that will be recognized by the chip as the hardware conditions during a Reset. If this condition is met, the chip will start executing the bootloader at the end of the Reset. See a detailed description in the applicable Document. – – Datasheet Bootloader CAN T89C51CC02. Datasheet Bootloader UART T89C51CC02.
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Hardware Security Byte
Table 32. Hardware Security byte
7 X2B Bit Number 6 BLJB 5 4 3 2 LB2 1 LB1 0 LB0
Bit Mnemonic Description X2 bit Set this bit to start in standard mode Clear this bit to start in X2 Mode. Boot Loader Jump bit - 1: To start the user’s application on next RESET (@0000h) located in FM0, - 0: To start the boot loader(@F800h) located in FM1. Reserved The value read from these bits are indeterminate. Lock bits (see Table 22)
7
X2B
6
BLJB
5-3 2-0
LB2:0
After erasing the chip in parallel mode, the default value is : FFh The erasing in ISP mode (from bootloader) does not modify this byte.
Notes: 1. Only the 4 MSB bits can be accessed by software. 2. The 4 LSB bits can only be accessed by parallel mode.
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Serial I/O Port
The T89C51CC02 I/O serial port is compatible with the I/O serial 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
Figure 20. Serial I/O Port Block Diagram
IB Bus
Write SBUF SBUF Receiver
Read SBUF
TXD
SBUF Transmitter Mode 0 Transmit
Load SBUF
RXD
Receive Shift register Serial Port Interrupt Request
RI
TI
SCON reg
Framing Error Detection Framing bit error detection is provided for the three asynchronous modes. To enable the
framing bit error detection feature, set SMOD0 bit in PCON register. Figure 21. Framing Error Block Diagram
SM0/FE
SM1
SM2
REN
TB8
RB8
TI
RI
Set FE bit if Stop bit is 0 (Framing Error) SM0 to UART Mode Control
SMOD1 SMOD0
-
POF
GF1
GF0
PD
IDL
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 bit is set. The software may examine the FE bit after each reception to check for data errors. Once set, only software or a reset clears the FE bit. Subsequently received frames with valid stop bits cannot clear the FE bit. When the FE feature is enabled, RI rises on the stop bit instead of the last data bit (See Figure 22 and Figure 23).
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Figure 22. UART Timing in Mode 1
RXD Start bit RI SMOD0 = x FE SMOD0 = 1 D0 D1 D2 D3 D4 D5 D6 D7 Stop bit
Data Byte
Figure 23. UART Timing 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 the 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 will the receiver set the RI bit in the SCON register to generate an interrupt. This ensures that the CPU is not interrupted by command frames addressed to other devices. If necessary, the user can 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 the 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
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Here 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 0011b SADEN1111 1101b Given1111 00X1b
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 0; for slaves B and C, bit 1 is a don’t care bit. To communicate with slaves A and B, but not slave C, 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.:
SADDR 0101 0110b SADEN 1111 1100b 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 Given1111 1X11b,
Slave B:SADDR1111 0011b SADEN1111 1001b Given1111 1X11B, Slave C:SADDR=1111 0010b SADEN1111 1101b Given1111 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.
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Registers
Table 33. SCON Register SCON (S:98h) Serial Control Register
7 FE/SM0 Bit Number 6 SM1 5 SM2 4 REN 3 TB8 2 RB8 1 TI 0 RI
Bit Mnemonic Description Framing Error bit (SMOD0 = 1) Clear to reset the error state, not cleared by a valid stop bit. Set by hardware when an invalid stop bit is detected. Serial port Mode bit 0 (SMOD0 = 0) Refer to SM1 for serial port mode selection. Serial port Mode bit 1 SM0 SM1 Mode 0 0 Shift Register 0 1 8-bit UART 1 0 9bit UART 1 1 9bit UART
FE 7 SM0
6
SM1
Baud Rate FXTAL/12 (or FXTAL/6 in mode X2) Variable FXTAL/64 or FXTAL/32 Variable
5
SM2
Serial port Mode 2 bit/Multiprocessor Communication Enable bit Clear to disable multiprocessor communication feature. Set to enable multiprocessor communication feature in mode 2 and 3. 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 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. 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
3
TB8
2
RB8
1
TI
0
RI
Reset Value = 0000 0000b bit addressable
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Table 34. SADEN Register SADEN (S:B9h) Slave Address Mask Register
7 6 5 4 3 2 1 0
Bit Number 7-0
Bit Mnemonic Description Mask Data for Slave Individual Address
Reset Value = 0000 0000b Not bit addressable Table 35. SADDR Register SADDR (S:A9h) Slave Address Register
7 6 5 4 3 2 1 0
Bit Number 7-0
Bit Mnemonic Description Slave Individual Address
Reset Value = 0000 0000b Not bit addressable Table 36. SBUF Register SBUF (S:99h) Serial Data Buffer
7 6 5 4 3 2 1 0
Bit Number 7-0
Bit Mnemonic Description Data sent/received by Serial I/O Port
Reset Value = 0000 0000b Not bit addressable
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Table 37. PCON Register PCON (S:87h) Power Control Register
7 SMOD1 Bit Number 7 6 SMOD0 5 4 POF 3 GF1 2 GF0 1 PD 0 IDL
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 Clear 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 Clear 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 Clear by hardware when interrupt or reset occurs. Set to enter idle mode.
6
SMOD0
5
-
4
POF
3
GF1
2
GF0
1
PD
0
IDL
Reset Value = 00X1 0000b Not bit addressable
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Timers/Counters
The T89C51CC02 implements two general-purpose, 16-bit Timers/Counters. Such are identified as Timer 0 and Timer 1, and can be independently configured to operate in a variety of modes as a Timer or an event Counter. When operating as a Timer, the Timer/Counter runs for a programmed length of time, then issues an interrupt request. When operating as a Counter, the Timer/Counter counts negative transitions on an external pin. After a preset number of counts, the Counter issues an interrupt request. The various operating modes of each Timer/Counter are described in the following sections. A basic operation is Timer registers THx and TLx (x = 0, 1) connected in cascade to form a 16-bit Timer. Setting the run control bit (TRx) in TCON register (See Figure 38) turns the Timer on by allowing the selected input to increment TLx. When TLx overflows it increments THx; when THx overflows it sets the Timer overflow flag (TFx) in TCON register. Setting the TRx does not clear the THx and TLx Timer registers. Timer registers can be accessed to obtain the current count or to enter preset values. They can be read at any time but TRx bit must be cleared to preset their values, otherwise the behavior of the Timer/Counter is unpredictable. The C/Tx# control bit selects Timer operation or Counter operation by selecting the divided-down peripheral clock or external pin Tx as the source for the counted signal. TRx bit must be cleared when changing the mode of operation, otherwise the behavior of the Timer/Counter is unpredictable. For Timer operation (C/Tx# = 0), the Timer register counts the divided-down peripheral clock. The Timer register is incremented once every peripheral cycle (6 peripheral clock periods). The Timer clock rate is fPER/6, i.e. fOSC/12 in standard mode or fOSC/6 in X2 Mode. For Counter operation (C/Tx# = 1), the Timer register counts the negative transitions on the Tx external input pin. The external input is sampled every peripheral cycles. When the sample is high in one cycle and low in the next one, the Counter is incremented. Since it takes 2 cycles (12 peripheral clock periods) to recognize a negative transition, the maximum count rate is fPER/12, i.e. fOSC/24 in standard mode or f OSC/12 in X2 Mode. There are no restrictions on the duty cycle of the external input signal, but to ensure that a given level is sampled at least once before it changes, it should be held for at least one full peripheral cycle.
Timer/Counter Operations
Timer 0
Timer 0 functions as either a Timer or event Counter in four modes of operation. Figure 24 through Figure 27 show the logical configuration of each mode. Timer 0 is controlled by the four lower bits of TMOD register (See Figure 39) and bits 0, 1, 4 and 5 of TCON register (See Figure 38). TMOD register selects the method of Timer gating (GATE0), Timer or Counter operation (T/C0#) and mode of operation (M10 and M00). TCON register provides Timer 0 control functions: overflow flag (TF0), run control bit (TR0), interrupt flag (IE0) and interrupt type control bit (IT0). For normal Timer operation (GATE0 = 0), setting TR0 allows TL0 to be incremented by the selected input. Setting GATE0 and TR0 allows external pin INT0# to control Timer operation. Timer 0 overflow (count rolls over from all 1s to all 0s) sets TF0 flag generating an interrupt request. It is important to stop Timer/Counter before changing mode.
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Mode 0 (13-bit Timer)
Mode 0 configures Timer 0 as an 13-bit Timer which is set up as an 8-bit Timer (TH0 register) with a modulo 32 prescaler implemented with the lower five bits of TL0 register (See Figure 24). The upper three bits of TL0 register are indeterminate and should be ignored. Prescaler overflow increments TH0 register.
Figure 24. Timer/Counter x (x= 0 or 1) in Mode 0
See section “Clock”
FTx CLOCK ÷6 0 1
THx (8 bits)
TLx (5 bits)
Overflow
TFx
TCON Reg
Tx C/Tx#
TMOD Reg
Timer x Interrupt Request
INTx# GATEx
TMOD Reg
TRx
TCON Reg
Mode 1 (16-bit Timer)
Mode 1 configures Timer 0 as a 16-bit Timer with TH0 and TL0 registers connected in cascade (See Figure 25). The selected input increments TL0 register.
Figure 25. Timer/Counter x (x= 0 or 1) in Mode 1
See section “Clock”
FTx CLOCK ÷6 0 1
THx (8 bits)
TLx (8 bits)
Overflow
TFx
TCON Reg
Tx C/Tx#
TMOD Reg
Timer x Interrupt Request
INTx# GATEx
TMOD Reg
TRx
TCON Reg
Mode 2 (8-bit Timer with AutoReload)
Mode 2 configures Timer 0 as an 8-bit Timer (TL0 register) that automatically reloads from TH0 register (See Figure 26). TL0 overflow sets TF0 flag in TCON register and reloads TL0 with the contents of TH0, which is preset by software. When the interrupt request is serviced, hardware clears TF0. The reload leaves TH0 unchanged. The next reload value may be changed at any time by writing it to TH0 register.
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Figure 26. Timer/Counter x (x= 0 or 1) in Mode 2
See section “Clock”
FTx CLOCK ÷6 0 1
TLx (8 bits)
Overflow
TFx
TCON Reg
Tx C/Tx#
TMOD Reg
Timer x Interrupt Request
INTx# GATEx
TMOD Reg
TRx
TCON Reg
THx (8 bits)
Mode 3 (Two 8-bit Timers)
Mode 3 configures Timer 0 such that registers TL0 and TH0 operate as separate 8-bit Timers (See Figure 27). This mode is provided for applications requiring an additional 8bit Timer or Counter. TL0 uses the Timer 0 control bits C/T0# and GATE0 in TMOD register, and TR0 and TF0 in TCON register in the normal manner. TH0 is locked into a Timer function (counting FPER /6) and takes over use of the Timer 1 interrupt (TF1) and run control (TR1) bits. Thus, operation of Timer 1 is restricted when Timer 0 is in mode 3.
Figure 27. Timer/Counter 0 in Mode 3: Two 8-bit Counters
FTx CLOCK ÷6 0 1
TL0 (8 bits)
Overflow
TF0
TCON.5
T0 C/T0#
TMOD.2
Timer 0 Interrupt Request
INT0# GATE0
TMOD.3
TR0
TCON.4
FTx CLOCK
÷6
TH0 (8 bits) TR1
TCON.6
Overflow
TF1
TCON.7
Timer 1 Interrupt Request
See section “Clock”
Timer 1
Timer 1 is identical to Timer 0 excepted for Mode 3 which is a hold-count mode. Following comments help to understand the differences: • Timer 1 functions as either a Timer or event Counter in three modes of operation. Figure 24 to Figure 26 show the logical configuration for modes 0, 1, and 2. Timer 1’s mode 3 is a hold-count mode. Timer 1 is controlled by the four high-order bits of TMOD register (See Figure 39) and bits 2, 3, 6 and 7 of TCON register (See Figure 38). TMOD register selects the method of Timer gating (GATE1), Timer or Counter operation (C/T1#) and mode of operation (M11 and M01). TCON register provides Timer 1 control functions: overflow flag (TF1), run control bit (TR1), interrupt flag (IE1) and interrupt type control bit (IT1). Timer 1 can serve as the Baud Rate Generator for the Serial Port. Mode 2 is best suited for this purpose. 59
•
•
4126J–CAN–05/06
•
For normal Timer operation (GATE1= 0), setting TR1 allows TL1 to be incremented by the selected input. Setting GATE1 and TR1 allows external pin INT1# to control Timer operation. Timer 1 overflow (count rolls over from all 1s to all 0s) sets the TF1 flag generating an interrupt request. When Timer 0 is in mode 3, it uses Timer 1’s overflow flag (TF1) and run control bit (TR1). For this situation, use Timer 1 only for applications that do not require an interrupt (such as a Baud Rate Generator for the Serial Port) and switch Timer 1 in and out of mode 3 to turn it off and on. It is important to stop Timer/Counter before changing mode.
• •
• Mode 0 (13-bit Timer)
Mode 0 configures Timer 1 as a 13-bit Timer, which is set up as an 8-bit Timer (TH1 register) with a modulo-32 prescaler implemented with the lower 5 bits of the TL1 register (See Figure 24). The upper 3 bits of TL1 register are ignored. Prescaler overflow increments TH1 register. Mode 1 configures Timer 1 as a 16-bit Timer with TH1 and TL1 registers connected in cascade (See Figure 25). The selected input increments TL1 register. Mode 2 configures Timer 1 as an 8-bit Timer (TL1 register) with automatic reload from TH1 register on overflow (See Figure 26). TL1 overflow sets TF1 flag in TCON register and reloads TL1 with the contents of TH1, which is preset by software. The reload leaves TH1 unchanged. Placing Timer 1 in mode 3 causes it to halt and hold its count. This can be used to halt Timer 1 when TR1 run control bit is not available i.e. when Timer 0 is in mode 3. Each Timer handles one interrupt source that is the timer overflow flag TF0 or TF1. This flag is set every time an overflow occurs. Flags are cleared when vectoring to the Timer interrupt routine. Interrupts are enabled by setting ETx bit in IEN0 register. This assumes interrupts are globally enabled by setting EA bit in IEN0 register. Figure 28. Timer Interrupt System
TF0
TCON.5
Mode 1 (16-bit Timer)
Mode 2 (8-bit Timer with AutoReload)
Mode 3 (Halt)
Interrupt
Timer 0 Interrupt Request ET0
IEN0.1
TF1
TCON.7
Timer 1 Interrupt Request ET1
IEN0.3
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Registers
Table 38. TCON Register TCON (S:88h) Timer/Counter Control Register
7 TF1 Bit Number 6 TR1 5 TF0 4 TR0 3 IE1 2 IT1 1 IE0 0 IT0
Bit Mnemonic Description Timer 1 Overflow Flag Cleared by hardware when processor vectors to interrupt routine. Set by hardware on Timer/Counter overflow, when Timer 1 register overflows. Timer 1 Run Control bit Clear to turn off Timer/Counter 1. Set to turn on Timer/Counter 1. Timer 0 Overflow Flag Cleared by hardware when processor vectors to interrupt routine. Set by hardware on Timer/Counter overflow, when Timer 0 register overflows. Timer 0 Run Control bit Clear to turn off Timer/Counter 0. Set to turn on Timer/Counter 0. Interrupt 1 Edge Flag Cleared by hardware when interrupt is processed if edge-triggered (See IT1). Set by hardware when external interrupt is detected on INT1# pin. Interrupt 1 Type Control bit Clear to select low level active (level triggered) for external interrupt 1 (INT1#). Set to select falling edge active (edge triggered) for external interrupt 1. Interrupt 0 Edge Flag Cleared by hardware when interrupt is processed if edge-triggered (See IT0). Set by hardware when external interrupt is detected on INT0# pin. Interrupt 0 Type Control bit Clear to select low level active (level triggered) for external interrupt 0 (INT0#). Set to select falling edge active (edge triggered) for external interrupt 0.
7
TF1
6
TR1
5
TF0
4
TR0
3
IE1
2
IT1
1
IE0
0
IT0
Reset Value = 0000 0000b
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Table 39. TMOD Register TMOD (S:89h) Timer/Counter Mode Control Register
7 GATE1 6 C/T1# 5 M11 4 M01 3 GATE0 2 C/T0# 1 M10 0 M00
Bit Number
Bit Mnemonic Description Timer 1 Gating Control bit Clear to enable Timer 1 whenever TR1 bit is set. Set to enable Timer 1 only while INT1# pin is high and TR1 bit is set. Timer 1 Counter/Timer Select bit Clear for Timer operation: Timer 1 counts the divided-down system clock. Set for Counter operation: Timer 1 counts negative transitions on external pin T1. Timer 1 Mode Select bits M11 M01 Operating mode 0 0 Mode 0: 8-bit Timer/Counter (TH1) with 5bit prescaler (TL1). 0 1 Mode 1: 16-bit Timer/Counter. 1 1 1 0 Mode 3: Timer 1 halted. Retains count. Mode 2: 8-bit auto-reload Timer/Counter (TL1).(1)
7
GATE1
6
C/T1#
5
M11
4
M01
3
GATE0
Timer 0 Gating Control bit Clear to enable Timer 0 whenever TR0 bit is set. Set to enable Timer/Counter 0 only while INT0# pin is high and TR0 bit is set. Timer 0 Counter/Timer Select bit Clear for Timer operation: Timer 0 counts the divided-down system clock. Set for Counter operation: Timer 0 counts negative transitions on external pin T0. Timer 0 Mode Select bit M10 M00 Operating mode 0 0 Mode 0: 8-bit Timer/Counter (TH0) with 5bit prescaler (TL0). 0 1 Mode 1: 16-bit Timer/Counter. 1 0 Mode 2: 8-bit auto-reload Timer/Counter (TL0).(2) 1 1 Mode 3: TL0 is an 8-bit Timer/Counter. TH0 is an 8-bit Timer using Timer 1’s TR0 and TF0 bits.
2
C/T0#
1
M10
0
M00
Reset Value = 0000 0000b
Notes: 1. Reloaded from TH1 at overflow. 2. Reloaded from TH0 at overflow.
Table 40. TH0 Register TH0 (S:8Ch) Timer 0 High Byte Register
7 6 5 4 3 2 1 0
Bit Number 7:0
Bit Mnemonic Description High Byte of Timer 0
Reset Value = 0000 0000b
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Table 41. TL0 Register TL0 (S:8Ah) Timer 0 Low Byte Register
7 6 5 4 3 2 1 0
Bit Number 7:0
Bit Mnemonic Description Low Byte of Timer 0
Reset Value = 0000 0000b Table 42. TH1 Register TH1 (S:8Dh) Timer 1 High Byte Register
7 6 5 4 3 2 1 0
Bit Number 7:0
Bit Mnemonic Description High Byte of Timer 1
Reset Value = 0000 0000b Table 43. TL1 Register TL1 (S:8Bh) Timer 1 Low Byte Register
7 6 5 4 3 2 1 0
Bit Number 7:0
Bit Mnemonic Description Low Byte of Timer 1
Reset Value = 0000 0000b
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Timer 2
The T89C51CC02 Timer 2 is compatible with Timer 2 in the 80C52. It is a 16-bit timer/counter: the count is maintained by two eightbit timer registers, TH2 and TL2 that are cascade-connected. It is controlled by T2CON register (See Table 45) and T2MOD register (See Table 46). Timer 2 operation is similar to Timer 0 and Timer 1. C/T2 s elects F T2 clock/6 (timer operation) or external pin T2 (counter operation) as timer clock. Setting TR2 allows TL2 to be incremented by the selected input. Timer 2 includes the following enhancements: • • Auto-reload mode (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. This feature is controlled by the DCEN bit in T2MOD register (See Table 45). Setting the DCEN bit enables Timer 2 to count up or down as shown in Figure 29. In this mode the T2EX pin controls the counting direction. 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 overflow or underflow, depending on the direction of the count. EXF2 does not generate an interrupt. This bit can be used to provide 17-bit resolution.
Figure 29. Auto-Reload Mode Up/Down Counter
See section “Clock”
FT2 CLOCK :6 0 1
TR2
T2CON.2
CT/2
T2CON.1
T2 (DOWN COUNTING RELOAD VALUE) T2EX: FFh (8-bit) FFh
(8-bit)
1=UP 2=DOWN TOGGLE T2CON Reg EXF2
TL2 (8-bit)
TH2 (8-bit)
TIMER 2 INTERRUPT T2CON Reg TF2
RCAP2L (8-bit)
RCAP2H (8-bit)
(UP COUNTING RELOAD VALUE)
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Programmable ClockOutput
In clock-out mode, Timer 2 operates as a 50%-duty-cycle, programmable clock generator (Figure 30). The input clock increments TL2 at frequency f OSC /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 depending on the system oscillator frequency and the value in the RCAP2H and RCAP2L registers:
– - ------------------------------------------- = --------------------------------------------
4 × ( 65536
For a 16 MHz system clock in x1 mode, Timer 2 has a programmable frequency range of 61 Hz (fOSC/216) to 4 MHz (fOSC/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 different 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. Figure 30. Clock-Out Mode
FT2 CLOCK
TL2 (8-bit)
TH2 (8-bit) OVERFLOW
TR2
T2CON.2
RCAP2L RCAP2H (8-bit) (8-bit) Toggle T2 Q Q D T2OE T2MOD reg
T2EX EXEN2 T2CON reg
EXF2 T2CON reg
4126J–CAN–05/06
L PA C R H P A C R k co l c T F
2 ⁄
TIMER 2 INTERRUPT
2
y cn euq e r F tu O – k co l C
2)
65
Registers
Table 44. T2CON Register T2CON (S:C8h) Timer 2 Control Register
7 TF2 Bit Number 6 EXF2 5 RCLK 4 TCLK 3 EXEN2 2 TR2 1 C/T2# 0 CP/RL2#
Bit Mnemonic Description Timer 2 Overflow Flag TF2 is not set if RCLK=1 or TCLK = 1. Must be cleared by software. Set by hardware on Timer 2 overflow. Timer 2 External Flag Set when a capture or a reload is caused by a negative transition on T2EX pin if EXEN2=1. Set to cause the CPU to vector to Timer 2 interrupt routine when Timer 2 interrupt is enabled. Must be cleared by software. Receive Clock bit Clear 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 Clear 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 Clear 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 Clear to turn off Timer 2. Set to turn on Timer 2. Timer/Counter 2 Select bit Clear for timer operation (input from internal clock system: fOSC). Set for counter operation (input from T2 input pin). 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. Clear 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.
7
TF2
6
EXF2
5
RCLK
4
TCLK
3
EXEN2
2
TR2
1
C/T2#
0
CP/RL2#
Reset Value = 0000 0000b bit addressable
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Table 45. T2MOD Register T2MOD (S:C9h) Timer 2 Mode Control Register
7 Bit Number 7 6 5 4 3 2 1 T2OE 0 DCEN
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 Clear 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 Clear to disable Timer 2 as up/down counter. Set to enable Timer 2 as up/down counter.
6
-
5
-
4
-
3
-
2
-
1
T2OE
0
DCEN
Reset Value = XXXX XX00b Not bit addressable Table 46. TH2 Register TH2 (S:CDh) Timer 2 High Byte Register
7 Bit Number 7-0 6 5 4 3 2 1 0 -
Bit Mnemonic Description High Byte of Timer 2
Reset Value = 0000 0000b Not bit addressable
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Table 47. TL2 Register TL2 (S:CCh) Timer 2 Low Byte Register
7 Bit Number 7-0 6 5 4 3 2 1 0 -
Bit Mnemonic Description Low Byte of Timer 2
Reset Value = 0000 0000b Not bit addressable Table 48. RCAP2H Register RCAP2H (S:CBh) Timer 2 Reload/Capture High Byte Register
7 Bit Number 7-0 6 5 4 3 2 1 0 -
Bit Mnemonic Description High Byte of Timer 2 Reload/Capture.
Reset Value = 0000 0000b Not bit addressable Table 49. RCAP2L Register RCAP2L (S:CAh) Timer 2 Reload/Capture Low Byte Register
7 Bit Number 7-0 6 5 4 3 2 1 0 -
Bit Mnemonic Description Low Byte of Timer 2 Reload/Capture.
Reset Value = 0000 0000b Not bit addressable
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Watchdog Timer
T89C51CC02 contains a powerful programmable hardware Watchdog Timer (WDT) that automatically resets the chip if it software fails to reset the WDT before the selected time interval has elapsed. It permits large Timeout ranging from 16ms to 2s @fOSC = 12 MHz in X1 mode. This WDT consists of a 14-bit counter plus a 7-bit programmable counter, a Watchdog Timer reset register (WDTRST) and a Watchdog Timer programming (WDTPRG) register. When exiting reset, the WDT is -by default- disable. To enable the WDT, the user has to write the sequence 1EH and E1H into WDTRST register with no instruction between the two writes. When the Watchdog Timer is enabled, it will increment every machine cycle while the oscillator is running and there is no way to disable the WDT except through reset (either hardware reset or WDT overflow reset). When WDT overflows, it will generate an output RESET pulse at the RST pin. The RESET pulse duration is 96xTOSC, where TOSC=1/fOSC. To make the best use of the WDT, it should be serviced in those sections of code that will periodically be executed within the time required to prevent a WDT reset
Note: When the watchdog is enable it is impossible to change its period.
Figure 31. Watchdog Timer
RESET WR
Decoder
Control WDTRST
Enable 14-bit Counter Fwd Clock WDTPRG 7-bit Counter
Outputs
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0
1
2
-
-
-
-
-
RESET
69
Watchdog Programming
The three lower bits (S0, S1, S2) located into WDTPRG register permit to program the WDT duration. Table 50. Machine Cycle Count
S2 0 0 0 0 1 1 1 1 S1 0 0 1 1 0 0 1 1 S0 0 1 0 1 0 1 0 1 Machine Cycle Count 214 - 1 215 - 1 216 - 1 217 - 1 218 - 1 219 - 1 220 - 1 221 - 1
To compute WD Timeout, the following formula is applied:
Note:
Svalue represents the decimal value of (S2 S1 S0)
Find Hereafter computed Timeout values for fOSCXTAL = 12 MHz in X1 mode Table 51. Timeout Computation
S2 0 0 0 0 1 1 1 1 S1 0 0 1 1 0 0 1 1 S0 0 1 0 1 0 1 0 1 fOSC=12 MHz 16.38 ms 32.77 ms 65.54 ms 131.07 ms 262.14 ms 524.29 ms 1.05 s 2.10 s fOSC=16MHz 12.28 ms 24.57 ms 49.14 ms 98.28 ms 196.56 ms 393.12 ms 786.24 ms 1.57 s fOSC =20 MHz 9.82 ms 19.66 ms 39.32 ms 78.64 ms 157.28 ms 314.56 ms 629.12 ms 1.25 s
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--------------------------------------- = --------------------------------------
6×2
(2
×2
eu l avS
2∧ 2
X c so F
XD W
tu O – em i T F
14
)
AT/T89C51CC02
Watchdog Timer During Power-down Mode and Idle
In Power-down mode the oscillator stops, which means the WDT also stops. While in Power-down mode, the user does not need to service the WDT. There are 2 methods of exiting Power-down mode: by a hardware reset or via a level activated external interrupt which is enabled prior to entering Power-down mode. When Power-down is exited with hardware reset, the watchdog is disabled. Exiting Power-down with an interrupt is significantly different. The interrupt shall be held low long enough for the oscillator to stabilize. When the interrupt is brought high, the interrupt is serviced. To prevent the WDT from resetting the device while the interrupt pin is held low, the WDT is not started until the interrupt is pulled high. It is suggested that the WDT be reset during the interrupt service for the interrupt used to exit Power-down. To ensure that the WDT does not overflow within a few states of exiting powerdown, it is best to reset the WDT just before entering powerdown. In the Idle mode, the oscillator continues to run. To prevent the WDT from resetting T89C51CC02 while in Idle mode, the user should always set up a timer that will periodically exit Idle, service the WDT, and re-enter Idle mode.
Register
Table 52. WDTPRG Register WDTPRG (S:A7h) – Watchdog Timer Duration Programming register
7 Bit Number 7 6 5 4 3 2 1 0 6 5 4 3 2 S2 1 S1 0 S0
Bit Mnemonic Description S2 S1 S0 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. Watchdog Timer Duration selection bit 2 Work in conjunction with bit 1 and bit 0. Watchdog Timer Duration selection bit 1 Work in conjunction with bit 2 and bit 0. Watchdog Timer Duration selection bit 0 Work in conjunction with bit 1 and bit 2.
Reset Value = XXXX X000b
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Table 53. WDTRST Register WDTRST (S:A6h Write Only) – Watchdog Timer Enable register
7 Bit Number 7 6 5 4 3 2 1 0 -
Bit Mnemonic Description Watchdog Control Value
Reset Value = 1111 1111b
Note: The WDRST register is used to reset/enable the WDT by writing 1EH then E1H in sequence without instruction between these two sequences.
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CAN Controller
The CAN Controller provides all the features required to implement the serial communication protocol CAN as defined by BOSCH GmbH. The CAN specification as referred to by ISO/11898 (2.0A & 2.0B) for high speed and ISO/11519-2 for low speed. The CAN Controller is able to handle all types of frames (Data, Remote, Error and Overload) and achieves a bitrate of 1-Mbit/s at 8 MHz1 Crystal frequency in X2 Mode.
Note: 1. At BRP = 1 sampling point will be fixed.
CAN Protocol
Principles
The CAN protocol is an international standard defined in the ISO 11898 for high speed and ISO 11519-2 for low speed. CAN is based on a broadcast communication mechanism. This broadcast communication is achieved by using a message oriented transmission protocol. These messages are identified by using a message identifier. Such a message identifier has to be unique within the whole network and it defines not only the content but also the priority of the message. The priority at which a message is transmitted compared to another less urgent message is specified by the identifier of each message. The priorities are laid down during system design in the form of corresponding binary values and cannot be changed dynamically. The identifier with the lowest binary number has the highest priority. Bus access conflicts are resolved by bit-wise arbitration on the identifiers involved by each node observing the bus level bit for bit. This happens in accordance with the "wired and" mechanism, by which the dominant state overwrites the recessive state. The competition for bus allocation is lost by all nodes with recessive transmission and dominant observation. All the "losers" automatically become receivers of the message with the highest priority and do not re-attempt transmission until the bus is available again.
Message Formats
The CAN protocol supports two message frame formats, the only essential difference being in the length of the identifier. The CAN standard frame, also known as CAN 2.0 A, supports a length of 11 bits for the identifier, and the CAN extended frame, also known as CAN 2.0 B, supports a length of 29 bits for the identifier.
Can Standard Frame Figure 32. CAN Standard Frames
Data Frame
Bus Idle SOF 11-bit identifier ID10..0 RTR IDE r0 4-bit DLC DLC4..0 0 - 8 bytes 15-bit CRC CRC ACK del. ACK del. 7 bits Intermission 3 bits Bus Idle (Indefinite)
Interframe Space
Arbitration Field
Control Field
Data Field
CRC Field
ACK Field
End of Frame
Interframe Space
Remote Frame
Bus Idle SOF 11-bit identifier ID10..0 RTR IDE r0 4-bit DLC DLC4..0 15-bit CRC CRC ACK del. ACK del. 7 bits Intermission 3 bits Bus Idle (Indefinite)
Interframe Space
Arbitration Field
Control Field
CRC Field
ACK Field
End of Frame
Interframe Space
A message in the CAN standard frame format begins with the "Start Of Frame (SOF)", this is followed by the "Arbitration field" which consist of the identifier and the "Remote Transmission Request (RTR)" bit used to distinguish between the data frame and the data request frame called remote frame. The following "Control field" contains the "IDentifier Extension (IDE)" bit and the "Data Length Code (DLC)" used to indicate the
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number of following data bytes in the "Data field". In a remote frame, the DLC contains the number of requested data bytes. The "Data field" that follows can hold up to 8 data bytes. The frame integrity is guaranteed by the following "Cyclic Redundant Check (CRC)" sum. The "ACKnowledge (ACK) field" compromises the ACK slot and the ACK delimiter. The bit in the ACK slot is sent as a recessive bit and is overwritten as a dominant bit by the receivers which have at this time received the data correctly. Correct messages are acknowledged by the receivers regardless of the result of the acceptance test. The end of the message is indicated by "End Of Frame (EOF)". The "Intermission Frame Space (IFS)" is the minimum number of bits separating consecutive messages. If there is no following bus access by any node, the bus remains idle. CAN Extended Frame Figure 33. CAN Extended Frames
Data Frame
Bus Idle SOF 11-bit base identifier IDT28..18 SRR IDE 18-bit identifier extension ID17..0 RTR r1 r0 4-bit DLC DLC4..0 0 - 8 bytes 15-bit CRC CRC ACK del. ACK del. 7 bits Intermission Bus Idle 3 bits (Indefinite)
Interframe Space
Arbitration Field
Control Field
Data Field
CRC Field
ACK Field
End of Frame
Interframe Space
Remote Frame
Bus Idle SOF 11-bit base identifier IDT28..18 SRR IDE 18-bit identifier extension ID17..0 RTR r1 r0 4-bit DLC DLC4..0 15-bit CRC CRC ACK del. ACK del. 7 bits Intermission 3 bits Bus Idle (Indefinite)
Interframe Space
Arbitration Field
Control Field
CRC Field
ACK Field
End of Frame
Interframe Space
A message in the CAN extended frame format is likely the same as a message in CAN standard frame format. The difference is the length of the identifier used. The identifier is made up of the existing 11-bit identifier (base identifier) and an 18-bit extension (identifier extension). The distinction between CAN standard frame format and CAN extended frame format is made by using the IDE bit which is transmitted as dominant in case of a frame in CAN standard frame format, and transmitted as recessive in the other case. Format Co-existence As the two formats have to co-exist on one bus, it is laid down which message has higher priority on the bus in the case of bus access collision with different formats and the same identifier / base identifier: The message in CAN standard frame format always has priority over the message in extended format. There are three different types of CAN modules available: – – – Bit Timing 2.0A - Considers 29 bit ID as an error 2.0B Passive - Ignores 29 bit ID messages 2.0B Active - Handles both 11 and 29 bit ID Messages
To ensure correct sampling up to the last bit, a CAN node needs to re-synchronize throughout the entire frame. This is done at the beginning of each message with the falling edge SOF and on each recessive to dominant edge. One CAN bit time is specified as four non-overlapping time segments. Each segment is constructed from an integer multiple of the Time Quantum. The Time Quantum or TQ is the smallest discrete timing resolution used by a CAN node.
Bit Construction
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Figure 34. CAN Bit Construction
CAN Frame (producer) Transmission Point (producer)
Nominal CAN Bit Time Time Quantum (producer) Segments (producer) SYNC_SEG
propagation delay
PROP_SEG
PHASE_SEG_1
PHASE_SEG_2
Segments (consumer)
SYNC_SEG
PROP_SEG
PHASE_SEG_1
PHASE_SEG_2
Sample Point
Synchronization Segment
The first segment is used to synchronize the various bus nodes. On transmission, at the start of this segment, the current bit level is output. If there is a bit state change between the previous bit and the current bit, then the bus state change is expected to occur within this segment by the receiving nodes.
Propagation Time Segment
This segment is used to compensate for signal delays across the network. This is necessary to compensate for signal propagation delays on the bus line and through the transceivers of the bus nodes.
Phase Segment 1
Phase Segment 1 is used to compensate for edge phase errors. This segment may be lengthened during resynchronization.
Sample Point
The sample point is the point of time at which the bus level is read and interpreted as the value of the respective bit. Its location is at the end of Phase Segment 1 (between the two Phase Segments). This segment is also used to compensate for edge phase errors. This segment may be shortened during resynchronization, but the length has to be at least as long as the information processing time and may not be more than the length of Phase Segment 1.
Phase Segment 2
Information Processing Time
It is the time required for the logic to determine the bit level of a sampled bit. The Information processing Time begins at the sample point, is measured in TQ and is fixed at 2 TQ for the Atmel CAN. Since Phase Segment 2 also begins at the sample point and is the last segment in the bit time, Phase Segment 2 minimum shall not be less than the Information processing Time.
Bit Lengthening
As a result of resynchronization, Phase Segment 1 may be lengthened or Phase Segment 2 may be shortened to compensate for oscillator tolerances. If, for example, the transmitter oscillator is slower than the receiver oscillator, the next falling edge used for resynchronization may be delayed. So Phase Segment 1 is lengthened in order to adjust the sample point and the end of the bit time.
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Bit Shortening
If, on the other hand, the transmitter oscillator is faster than the receiver one, the next falling edge used for resynchronization may be too early. So Phase Segment 2 in bit N is shortened in order to adjust the sample point for bit N+1 and the end of the bit time The limit to the amount of lengthening or shortening of the Phase Segments is set by the Resynchronization Jump Width. This segment may not be longer than Phase Segment 2.
Synchronization Jump Width
Programming the Sample Point
Programming of the sample point allows "tuning" of the characteristics to suit the bus. Early sampling allows more Time Quanta in the Phase Segment 2 so the Synchronization Jump Width can be programmed to its maximum. This maximum capacity to shorten or lengthen the bit time decreases the sensitivity to node oscillator tolerances, so that lower cost oscillators such as ceramic resonators may be used. Late sampling allows more Time Quanta in the Propagation Time Segment which allows a poorer bus topology and maximum bus length.
Arbitration Figure 35. Bus Arbitration
Arbitration lost
node A TXCAN node B TXCAN
Node A loses the bus Node B wins the bus
CAN bus
SOF ID10 ID9 ID8 ID7 ID6 ID5 ID4 ID3 ID2 ID1 ID0 RTR IDE
---------
The CAN protocol handles bus accesses according to the concept called “Carrier Sense Multiple Access with Arbitration on Message Priority”. During transmission, arbitration on the CAN bus can be lost to a competing device with a higher priority CAN Identifier. This arbitration concept avoids collisions of messages whose transmission was started by more than one node simultaneously and makes sure the most important message is sent first without time loss. The bus access conflict is resolved during the arbitration field mostly over the identifier value. If a data frame and a remote frame with the same identifier are initiated at the same time, the data frame prevails over the remote frame (c.f. RTR bit). Errors The CAN protocol signals any errors immediately as they occur. Three error detection mechanisms are implemented at the message level and two at the bit level: • Cyclic Redundancy Check (CRC) The CRC safeguards the information in the frame by adding redundant check bits at the transmission end. At the receiver these bits are re-computed and tested against the received bits. If they do not agree there has been a CRC error. Frame Check This mechanism verifies the structure of the transmitted frame by checking the bit
Error at Message Level
•
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fields against the fixed format and the frame size. Errors detected by frame checks are designated "format errors". • ACK Errors As already mentioned frames received are acknowledged by all receivers through positive acknowledgement. If no acknowledgement is received by the transmitter of the message an ACK error is indicated. Monitoring The ability of the transmitter to detect errors is based on the monitoring of bus signals. Each node which transmits also observes the bus level and thus detects differences between the bit sent and the bit received. This permits reliable detection of global errors and errors local to the transmitter. Bit Stuffing The coding of the individual bits is tested at bit level. The bit representation used by CAN is "Non Return to Zero (NRZ)" coding, which guarantees maximum efficiency in bit coding. The synchronization edges are generated by means of bit stuffing.
Error at Bit Level
•
•
Error Signalling
If one or more errors are discovered by at least one node using the above mechanisms, the current transmission is aborted by sending an "error flag". This prevents other nodes accepting the message and thus ensures the consistency of data throughout the network. After transmission of an erroneous message that has been aborted, the sender automatically re-attempts transmission.
CAN Controller Description
The CAN controller accesses are made through SFR. Several operations are possible by SFR: • • arithmetic and logic operations, transfers and program control (SFR is accessible by direct addressing). 4 independent message objects are implemented, a pagination system manages their accesses.
Any message object can be programmed in a reception buffer block (even non-consecutive buffers). For the reception of defined messages one or several receiver message objects can be masked without participating in the buffer feature. An IT is generated when the buffer is full. The frames following the buffer-full interrupt will not be taken into account until at least one of the buffer message objects is re-enabled in reception. Higher priority of a message object for reception or transmission is given to the lower message object number. The programmable 16-bit Timer (CANTIMER) is used to stamp each received and sent message in the CANSTMP register. This timer starts counting as soon as the CAN controller is enabled by the ENA bit in the CANGCON register. The Time Trigger Communication (TTC) protocol is supported by the T89C51CC02.
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Figure 36. CAN Controller Block Diagram bit Stuffing /Destuffing TxDC RxDC bit Timing Logic Error Counter Rec/Tec Cyclic Redundancy Check Receive Transmit
Page Register
DPR(Mailbox + Registers)
Priority Encoder
µC-Core Interface
Interface Bus
Core Control
CAN Controller Mailbox and Registers Organization
The pagination allows management of the 91 registers including 80(4 x 20) Bytes of mailbox via 32 SFRs. All actions on the message object window SFRs apply to the corresponding message object registers pointed by the message object number find in the Page message object register (CANPAGE) as illustrate in Figure 37.
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Figure 37. CAN Controller Memory Organization SFRs
General Control General Status General Interrupt bit Timing - 1 bit Timing - 2 bit Timing - 3 Enable message object Enable Interrupt Enable Interrupt message object Status Interrupt message object
On-chip CAN Controller Registers
Timer Control
CANTimer High
CANTimer Low
TimTTC High TimTTC Low TEC counter
REC counter
Page message object
(message object number) (Data offset) 4 Message Objects
message object 0 - Status message object 0 - Control & DLC message object Status message object Control & DLC Message Data ID Tag - 1 ID Tag - 2 ID Tag - 3 ID Tag - 4 ID Mask - 1 ID Mask - 2 ID Mask - 3 ID Mask - 4 TimStmp High TimStmp Low
8 Bytes
message object 3 - Status message object 3 - Control & DLC Ch.3 - Message Data - byte 0
Ch.0 - Message Data - byte 0
Ch.0 - ID Tag Ch.0 - ID Tag Ch.0 - ID Tag Ch.0 - ID Tag -
1 2 3 4
Ch.3 - ID Tag - 1 Ch.3 - ID Tag - 2 Ch.3 - ID Tag - 3 Ch.3 - ID Tag - 4 Ch.3 - ID Mask Ch.3 - ID Mask Ch.3 - ID Mask Ch.3 - ID Mask 1 2 3 4
Ch.0 - ID Mask- 1 Ch.0 - ID Mask- 2 Ch.0 - ID Mask- 3 Ch.0 - ID Mask - 4 Ch.0 TimStmp High Ch.0 TimStmp Low
Ch.3 TimStmp High Ch.3 TimStmp Low
message object Window SFRs
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Working on Message Objects
The Page message object register (CANPAGE) is used to select one of the 4 message objects. Then, message object Control (CANCONCH) and message object Status (CANSTCH) are available for this selected message object number in the corresponding SFRs. A single register (CANMSG) is used for the message. The mailbox pointer is managed by the Page message object register with an auto-incrementation at the end of each access. The range of this counter is 8. Note that the maibox is a pure RAM, dedicated to one message object, without overlap. In most cases, it is not necessary to transfer the received message into the standard memory. The message to be transmitted can be built directly in the maibox. Most calculations or tests can be executed in the mailbox area which provide quicker access. In order to enable the CAN Controller correctly the following registers have to be initialized: • • • General Control (CANGCON), bit Timing (CANBT 1, 2 & 3), And for each page of 15 message objects: – – Message object Control (CANCONCH), Message object Status (CANSTCH).
CAN Controller Management
During operation, the CAN Enable message object registers (CANEN) gives a fast overview of the message objects availability. The CAN messages can be handled by interrupt or polling modes. A message object can be configured as follows: • • • • Transmit message object Receive message object Receive buffer message object Disable
This configuration is made in the CONCH field of the CANCONCH register (See Table 54). When a message object is configured, the corresponding ENCH bit of CANEN register is set. Table 54. Configuration for CONCH1:2
CONCH 1 0 0 1 1 CONCH 2 0 1 0 1 Type of Message Object Disable Transmitter Receiver Receiver buffer
When a Transmitter or Receiver action of a message object is completed, the corresponding ENCH bit of the CANEN register is cleared. In order to re-enable the message object, it is necessary to re-write the configuration in CANCONCH register. Non-consecutive message objects can be used for all three types of message objects (Transmitter, Receiver and Receiver buffer).
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Buffer Mode Any message object can be used to define one buffer, including non-consecutive message objects, and with no limitation in number of message objects used up to 4. Each message object of the buffer must be initialized CONCH2 = 1 and CONCH1 = 1; Figure 38. Buffer Mode Block buffer buffer 1 buffer 0
message object 3 message object 2 message object 1 message object 0
The same acceptance filter must be defined for each message objects of the buffer. When there is no mask on the identifier or the IDE, all messages are accepted. A received frame will always be stored in the lowest free message object. When the flag RxOk is set on one of the buffer message objects, this message object can then be read by the application. This flag must then be cleared by the software and the message object re-enabled in buffer reception in order to free the message object. The OVRBUF flag in the CANGIT register is set when the buffer is full. This flag can generate an interrupt. The frames following the buffer-full interrupt will not be stored and no status will be overwritten in the CANSTCH registers involved in the buffer until at least one of the buffer message objects is re-enabled in reception. This flag must be cleared by the software in order to acknowledge the interrupt.
IT CAN Management
The different interrupts are: • • • • • Transmission interrupt Reception interrupt Interrupt on error (bit error, stuff error, crc error, form error, acknowledge error) Interrupt when Buffer receive is full Interrupt on overrun of CAN Timer
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Figure 39. CAN Controller Interrupt Structure
CANGIE.5 CANGIE.4 CANGIE.3
ENRX
ENTX ENERCH
RXOK i
CANSTCH.5
CANSIT
SIT i
CANIE
TXOK i
CANSTCH.6
BERR i
CANSTCH.4
EICH i
i=0
CANGIT.7
SERR i
CANSTCH.3
CERR i
CANSTCH.2
SIT i
i=4
CANIT
IEN1.0
FERR i
CANSTCH.1 CANGIE.2
AERR i
CANSTCH.0
ENBUF
ECAN
OVRBUF
CANGIT.4 CANGIE.1
CANIT
SERG
CANGIT.3
ENERG
CERG
CANGIT.2
FERG
CANGIT.1 IEN1.2
AERG
CANGIT.0
ETIM
OVRTIM
CANGIT.5
OVRIT To enable a transmission interrupt: • • • • • • • • • • • Enable General CAN IT in the interrupt system register Enable interrupt by message object, EICHi Enable transmission interrupt, ENTX Enable General CAN IT in the interrupt system register Enable interrupt by message object, EICHi Enable reception interrupt, ENRX Enable General CAN IT in the interrupt system register Enable interrupt by message object, EICHi Enable interrupt on error, ENERCH Enable General CAN IT in the interrupt system register Enable interrupt on error, ENERG
To enable a reception interrupt:
To enable an interrupt on message object error:
To enable an interrupt on general error:
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To enable an interrupt on Buffer-full condition: • • • Enable General CAN IT in the interrupt system register Enable interrupt on Buffer full, ENBUF Enable Overrun IT in the interrupt system register
To enable an interrupt when Timer overruns:
When an interrupt occurs, the corresponding message object bit is set in the SIT register. To acknowledge an interrupt, the corresponding CANSTCH bits (RXOK, TXOK,...) or CANGIT bits (OVRTIM, OVRBUF,...), must be cleared by the software application. When the CAN node is in transmission and detects a Form Error in its frame, a bit Error will also be raised. Consequently, two consecutive interrupts can occur, both due to the same error. When a message object error occurs and is set in CANSTCH register, no general error are set in CANGIE register.
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Bit Timing and Baud Rate
FSM’s (Finite State Machine) of the CAN channel need to be synchronous to the time quantum. So, the input clock for bit timing is the clock used into CAN channel FSM’s. Field and segment abbreviations: • • • • • • • • BRP: Baud Rate Prescaler. TQ: Time Quantum (output of Baud Rate Prescaler). SYNS: SYNchronization Segment is 1 TQ long. PRS: PRopagation time Segment is programmable to be 1, 2, ..., 8 TQ long. PHS1: PHase Segment 1 is programmable to be 1, 2, ..., 8 TQ long. PHS2: PHase Segment 2 is programmable to be superior or eual to the Information Processing Time and inferior or equal to TPHS1 INFORMATION PROCESSING TIME is 2 TQ. SJW: (Re) Synchronization Jump Width is programmable to be minimum of PHS1 and 4.
The total number of TQ in a bit time has to be programmed at least from 8 to 25.
Figure 40. Sample and Transmission Point
bit Timing System Clock Tscl Time Quantum PRS 3bit length PHS1 3bit length PHS2 3bit length SJW 2-bit length Sample Point Transmission Point
FCAN CLOCK
Prescaler BRP
The baud rate selection is made by Tbit calculation: Tbit = Tsyns + Tprs + Tphs1 + Tphs2 1. Tsyns = Tscl = (BRP[5..0]+ 1)/Fcan = 1TQ 2. Tprs = (1 to 8) * Tscl = (PRS[2..0]+ 1) * Tscl 3. Tphs1 = (1 to 8) * Tscl = (PHS1[2..0]+ 1) * Tscl 4. Tphs2 = (1 to 8) * Tscl = (PHS2[2..0]+ 1) * Tscl Tphs2 = Max of (Tphs1 and 2TQ) 5. Tsjw = (1 to 4) * Tscl = (SJW[1..0]+ 1) * Tscl The total number of Tscl (Time Quanta) in a bit time must be comprised between 8 to 25.
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Figure 41. General Structure of a bit Period
1/ Fcan Oscillator Tscl System Clock bit Rate Prescaler
Data Tsyns (*) (1) Phase error ≤ 0 (2) Phase error ≥ 0 (3) Phase error > 0 (4) Phase error < 0
One Nominal bit
Tprs Tphs1 (1) Tphs1 + Tsjw (3) Tphs2 - Tsjw (4) Tbit (*) Synchronization Segment: SYNS Tsyns = 1xTscl (fixed) Sample Point Transmission Point Tphs2 (2)
Tbit calculation: Tbit = Tsyns + Tprs + Tphs 1 + Tphs 2
example of bit timing determination for CAN baudrate of 500 kbit/s: FOSC = 12 MHz in X1 mode => FCAN = 6MHz Verify that the CAN baud rate you want is an integer division of FCAN clock. FCAN/CANbaudrate = 6 MHz/500 kHz = 12 The time quanta TQ must be comprised between 8 and 25: TQ = 12 and BRP = 0 Define the various timing parameters: Tbit = Tsyns + Tprs + Tphs1 + Tphs2 = 12TQ Tsyns = 1TQ and Tsjw =1TQ => SJW = 0 If we chose a sample point at 66.6% => Tphs2 = 4TQ => PHS2 = 3 Tbit = 12 = 4 + 1 + Tphs1 + Tprs, let us choose Tprs = 3 Tphs1 = 4 PHS1 = 3 and PRS = 2 BRP = 0 so CANBT1 = 00h SJW = 0 and PRS = 2 so CANBT2 = 04h PHS2 = 3 and PHS1 = 3 so CANBT3 = 36h
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Fault Confinement
With respect to fault confinement, a unit may be in one of the three following status: • • • Error active Error passive Bus off
An error active unit takes part in bus communication and can send an active error frame when the CAN macro detects an error. An error passive unit cannot send an active error frame. It takes part in bus communication, but when an error is detected, a passive error frame is sent. Also, after a transmission, an error passive unit will wait before initiating further transmission. A bus off unit is not allowed to have any influence on the bus. For fault confinement, two error counters (TEC and REC) are implemented. See CAN Specification for details on Fault confinement. Figure 42. Line Error Mode ERRP = 0 BOFF = 0
Init. Error Active
TEC: Transmit Error Counter REC : Receive Error Counter
TEC >127 or REC>127
TEC IDT0-29 RTR => RTRTAG RB => RB0-1TAG IDE => IDE in CANCONCH register Figure 43. Acceptance Filter Block Diagram
RxDC Rx Shift Register (internal)
ID & RB 13/32 13/32 RTR IDE
=
13/32 Write Enable 13/32 1 13/32
Hit (Ch i)
ID TAG Registers (Ch i) & CanConch
ID & RB RTR IDE
ID MSK Registers (Ch i)
ID & RB RTR IDE
example: To accept only ID = 318h in part A. ID MSK = 111 1111 1111 b ID TAG = 011 0001 1000 b
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Data and Remote Frame
Description of the different steps for: • Data frame
Node A
RT R EN CH RP L TX V RXOK OK
Node B
RT R EN CH RP L TX V O RX K O K
message object in transmission 0 1 uu message object disabled 00 uc
x 00 u uu x 10 u cu
DA
TA
FR AM
01 uu
E
x 00 u uu x 01 u uc
message object in reception
00 uc
message object disabled
•
Remote frame, with automatic reply
RT R EN CH RP L TX V O RX K OK
RT R EN CH RP L TX V RXOK O K
RE MO TE FR AM E
ME FRA ) TA diate DA me (im
message object in transmission
11 uu 01 cu 00 uc
x 00 u uu x 10 u cu x 01 u uc
11 uu 01 cu 00 uc
1 00 u uu 0 00 c uu 0 10 c cu
message object in reception
message object in reception by CAN controller message object disabled
message object in transmission by CAN controller message object disabled
•
Remote frame
RT R EN CH RP L TX V RXOK O K
RT R EN CH RP L TX V O RX K OK
RE MO TE F
message object in transmission message object disabled
11 uu 01 cu
x 00 u uu x 10 u cu
11 uu
RA M E
0 00 u uu 0 01 u uc
message object in reception
10 uc
message object disabled
message object in reception by user
00 cc
x 01 u uc
E AM FR ) TA rred DA e fe (d
01 uu 00 uc
x 00 u uu x 10 u cu
message object in transmission by user
message object disabled
i u : modified by user
i c : modified by CAN
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Time Trigger Communication (TTC) and Message Stamping
The T89C51CC02 has a programmable 16-bit Timer (CANTIMH&CANTIML) for message stamp and TTC. This CAN Timer starts after the CAN controller is enabled by the ENA bit in the CANGCON register. Two modes in the timer are implemented: • Time Trigger Communication: – Capture of this timer value in the CANTTCH & CANTTCL registers on Start Of Frame (SOF) or End Of Frame (EOF), depending on the SYNCTTC bit in the CANGCON register, when the network is configured in TTC by the TTC bit in the CANGCON register.
In this mode, CAN only sends the frame once, even if an error occurs.
Note:
•
Message Stamping – – – – Capture of this timer value in the CANSTMPH & CANSTMPL registers of the message object which received or sent the frame. All messages can be stamps. The stamping of a received frame occurs when the RxOk flag is set. The stamping of a sent frame occurs when the TxOk flag is set.
The CAN Timer works in a roll-over from FFFFh to 0000h which serves as a time base. When the timer roll-over from FFFFh to 0000h, an interrupt is generated if the ETIM bit in the interrupt enable register IEN1 is set. Figure 44. Block Diagram of CAN Timer
When 0xFFFF to 0x0000
OVRTIM
CANGIT.5
Fcan CLOCK
÷6
CANTCON
CANGCON.1
ENA
CANGCON.5 CANGCON.4 TTC SYNCTTC
CANTIMH & CANTIML TXOK i
CANSTCH.4
SOF on CAN frame EOF on CAN frame
RXOK i
CANSTCH.5
CANSTMPH & CANSTMPL
CANTTCH & CANTTCL
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CAN Autobaud and Listening Mode
To activate the Autobaud feature, the AUTOBAUD bit in the CANGCON register must be set. In this mode, the CAN controller is only listening to the line without acknowledging the received messages. It cannot send any message. The error flags are updated. The bit timing can be adjusted until no error occurs (good configuration find). In this mode, the error counters are frozen. To go back to the standard mode, the AUTOBAUD bit must be cleared. Figure 45. Autobaud Mode
TxDC TxDC
AUTOBAUD CANGCON.3
RxDC
1
RxDC
0
Routine Examples
1. Init of CAN macro // Reset the CAN macro CANGCON = 01h; // Disable CAN interrupts ECAN ETIM = 0; = 0;
// Init the Mailbox for num_page =0; num_page Enable IT’s of message objects 3 & 2. 3 IECH 3 2 IECH 2 1 IECH 1 0 IECH 0
7-4
-
3-0
IECH3:0
Reset Value = xxxx 0000b Table 65. CANBT1 Register CANBT1 (S:B4h) – CAN bit Timing Registers 1
7 Bit Number 7 6 BRP 5 5 BRP 4 4 BRP 3 Description Reserved The value read from this bit is indeterminate. Do not set this bit. Baud Rate Prescaler The period of the CAN controller system clock Tscl is programmable and determines the individual bit timing.(1) 6-1 BRP5:0 BRP[5..0] + 1 Tscl = FCAN Reserved The value read from this bit is indeterminate. Do not set this bit. 3 BRP 2 2 BRP 1 1 BRP 0 0 -
Bit Mnemonic -
0
-
Note:
1. The CAN controller bit timing registers must be accessed only if the CAN controller is disabled with the ENA bit of the CANGCON register set to 0. See Figure 41.
No default value after reset.
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Table 66. CANBT2 Register CANBT2 (S:B5h) – CAN bit Timing Registers 2
7 Bit Number 7 6 SJW 1 5 SJW 0 4 Description Reserved The value read from this bit is indeterminate. Do not set this bit. Re-synchronization Jump Width To compensate for phase shifts between clock oscillators of different bus controllers, the controller must re-synchronize on any relevant signal edge of the current transmission. The synchronization jump width defines the maximum number of clock cycles. A bit period may be shortened or lengthened by a resynchronization. Tsjw = Tscl x (SJW [1..0] +1) Reserved The value read from this bit is indeterminate. Do not set this bit. Programming Time Segment This part of the bit time is used to compensate for the physical delay times within the network. It is twice the sum of the signal propagation time on the bus line, the input comparator delay and the output driver delay. Tprs = Tscl x (PRS[2..0] + 1) Reserved The value read from this bit is indeterminate. Do not set this bit. 3 PRS 2 2 PRS 1 1 PRS 0 0 -
Bit Mnemonic -
6-5
SJW1:0
4
-
3-1
PRS2:0
0
-
Note:
1. The CAN controller bit timing registers must be accessed only if the CAN controller is disabled with the ENA bit of the CANGCON register set to 0. See Figure 41.
No default value after reset.
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Table 67. CANBT3 Register CANBT3 (S:B6h) CAN bit Timing Registers 3
7 Bit Number 7 6 PHS2 2 5 PHS2 1 4 PHS2 0 Description Reserved The value read from this bit is indeterminate. Do not set this bit. Phase Segment 2 This phase is used to compensate for phase edge errors. This segment can be shortened by the re-synchronization jump width. 6-4 PHS2 2:0 Tphs2 = Tscl x (PHS2[2..0] + 1) Phasse segment 2 is the maximum of Phase segment1 and the Information Processing Time (= 2TQ). Phase Segment 1 This phase is used to compensate for phase edge errors. This segment can be lengthened by the re-synchronization jump width. Tphs1 = Tscl x (PHS1[2..0] + 1) 3 PHS1 2 2 PHS1 1 1 PHS1 0 0 SMP
Bit Mnemonic -
3-1
PHS1 2:0
0
SMP
Sample Type 0 - once, at the sample point. 1 - three times, the threefold sampling of the bus is the sample point and twice over a distance of a 1/2 period of the Tscl. The result corresponds to the majority decision of the three values.
Note:
1. The CAN controller bit timing registers must be accessed only if the CAN controller is disabled with the ENA bit of the CANGCON register set to 0. See Figure 41.
No default value after reset.
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Table 68. CANPAGE Register CANPAGE (S:B1h) – CAN Message Object Page Register
7 Bit Number 6 5 CHNB 1 Bit Mnemonic 4 CHNB 0 Description Reserved The values read from these bits are indeterminate. Do not set these bits. Selection of Message Object Number The available numbers are: 0 to 3(See Figure 37). Auto Increment of the Index (Active Low) 0 - auto-increment of the index (default value). 1 - non-auto-increment of the index. Index Byte location of the data field for the defined message object (See Figure 37). 3 AINC 2 INDX2 1 INDX1 0 INDX0
7-6
-
5-4
CHNB3:0
3
AINC
2-0
INDX2:0
Reset Value = xx00 0000b Table 69. CANCONCH Register CANCONCH (S:B3h) – CAN Message Object Control and DLC Register
7 CONCH 1 6 CONCH 0 5 RPLV 4 IDE Description Configuration of Message Object CONCH1 CONCH0 0 0: disable 0 1: Launch transmission 1 0: Enable Reception 1 1: Enable Reception Buffer NOTE: The user must re-write the configuration to enable the corresponding bit in the CANEN1:2 registers. Reply valid Used in the automatic reply mode after receiving a remote frame 0 - reply not ready. 1 - reply ready & valid. Identifier Extension 0 - CAN standard rev 2.0 A (ident = 11 bits). 1 - CAN standard rev 2.0 B (ident = 29 bits). Data Length Code Number of Bytes in the data field of the message. The range of DLC is from 0 up to 8. This value is updated when a frame is received (data or remote frame). If the expected DLC differs from the incoming DLC, a warning appears in the CANSTCH register. 3 DLC 3 2 DLC 2 1 DLC 1 0 DLC 0
Bit Number
Bit Mnemonic
7-6
CONCH1:0
5
RPLV
4
IDE
3-0
DLC3:0
No default value after reset
103
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Table 70. CANSTCH Register CANSTCH (S:B2h) – CAN Message Object Status Register
7 DLCW Bit Number 6 TXOK 5 RXOK 4 BERR Description Data Length Code Warning The incoming message does not have the DLC expected. Whatever the frame type, the DLC field of the CANCONCH register is updated by the received DLC. Transmit OK The communication enabled by transmission is completed. When the controller is ready to send a frame, if two or more message objects are enabled as producers, the lower index message object (0 to 13) is supplied first. Must be cleared by software. This flag can generate an interrupt. Receive OK The communication enabled by reception is completed. In the case of two or more message object reception hits, the lower index message object (0 to 13) is updated first. Must be cleared by software. This flag can generate an interrupt. bit Error (only in transmission) The bit value monitored is different from the bit value sent. Exceptions: the monitored recessive bit sent as a dominant bit during the arbitration field and the acknowledge slot detecting a dominant bit during the sending of an error frame. Must be cleared by software. This flag can generate an interrupt. Stuff Error Detection of more than five consecutive bits with the same polarity. Must be cleared by software. This flag can generate an interrupt. CRC Error The receiver performs a CRC check on each destuffed received message from the start of frame up to the data field. If this checking does not match with the destuffed CRC field, a CRC error is set. Must be cleared by software. This flag can generate an interrupt. Form Error The form error results from one or more violations of the fixed form in the following bit fields: CRC delimiter acknowledgment delimiter end_of_frame Must be cleared by software. This flag can generate an interrupt. Acknowledgment Error No detection of the dominant bit in the acknowledge slot. Must be cleared by software. This flag can generate an interrupt. 3 SERR 2 CERR 1 FERR 0 AERR
Bit Mnemonic
7
DLCW
6
TXOK
5
RXOK
4
BERR
3
SERR
2
CERR
1
FERR
0
AERR
Note:
See Figure 39.
No default value after reset.
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Table 71. CANIDT1 Register for V2.0 part A CANIDT1 for V2.0 part A (S:BCh) – CAN Identifier Tag Registers 1
7 IDT 10 Bit Number 7-0 6 IDT 9 5 IDT 8 4 IDT 7 Description IDentifier Tag Value See Figure 43. 3 IDT 6 2 IDT 5 1 IDT 4 0 IDT 3
Bit Mnemonic IDT10:3
No default value after reset. Table 72. CANIDT2 Register for V2.0 part A CANIDT2 for V2.0 part A (S:BDh) – CAN Identifier Tag Registers 2
7 IDT 2 Bit Number 7-5 6 IDT 1 5 IDT 0 4 Description IDentifier Tag Value See Figure 43. Reserved The values read from these bits are indeterminate. Do not set these bits. 3 2 1 0 -
Bit Mnemonic IDT2:0
4-0
-
No default value after reset. Table 73. CANIDT3 Register for V2.0 part A CANIDT3 for V2.0 part A (S:BEh) –CAN Identifier Tag Registers 3
7 Bit Number 6 5 Bit Mnemonic 4 Description Reserved The values read from these bits are indeterminate. Do not set these bits. 3 2 1 0 -
7-0
-
No default value after reset.
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Table 74. CANIDT1 for V2.0 part A CANIDT4 for V2.0 part A (S:BFh) CAN Identifier Tag Registers 4
7 Bit Number 6 5 Bit Mnemonic 4 Description Reserved The values read from these bits are indeterminate. Do not set these bits. Remote transmission request tag value. Reserved The values read from this bit are indeterminate. Do not set these bit. Reserved bit 0 tag value. 3 2 RTRTAG 1 0 RB0TAG
7-3
-
2
RTRTAG
1
-
0
RB0TAG
No default value after reset. Table 75. CANIDT2Register for V2.0 part A CANIDT1 for V2.0 Part B (S:BCh) CAN Identifier Tag Registers 1
7 IDT 28 Bit Number 7-0 6 IDT 27 5 IDT 26 4 IDT 25 Description IDentifier Tag Value See Figure 43. 3 IDT 24 2 IDT 23 1 IDT 22 0 IDT 21
Bit Mnemonic IDT28:21
No default value after reset. Table 76. CANIDT2 Register for V2.0 Part B CANIDT2 for V2.0 Part B (S:BDh) CAN Identifier Tag Registers 2
7 IDT 20 Bit Number 7-0 6 IDT 19 5 IDT 18 4 IDT 17 Description IDentifier Tag Value See Figure 43. 3 IDT 16 2 IDT 15 1 IDT 14 0 IDT 13
Bit Mnemonic IDT20:13
No default value after reset.
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Table 77. CANIDT3 Register for V2.0 Part B CANIDT3 for V2.0 Part B (S:BEh) CAN Identifier Tag Registers 3
7 IDT 12 Bit Number 7-0 6 IDT 11 5 IDT 10 4 IDT 9 Description IDentifier Tag Value See Figure 43. 3 IDT 8 2 IDT 7 1 IDT 6 0 IDT 5
Bit Mnemonic IDT12:5
No default value after reset. Table 78. CANIDT4 Register for V2.0 Part B CANIDT4 for V2.0 Part B (S:BFh) CAN Identifier Tag Registers 4
7 IDT 4 Bit Number 7-3 2 1 0 6 IDT 3 5 IDT 2 4 IDT 1 Description IDentifier Tag Value See Figure 43. Remote Transmission Request Tag Value Reserved bit 1 tag value. Reserved bit 0 tag value. 3 IDT 0 2 RTRTAG 1 RB1TAG 0 RB0TAG
Bit Mnemonic IDT4:0 RTRTAG RB1TAG RB0TAG
No default value after reset.
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Table 79. CANIDM1 Register for V2.0 part A CANIDM1 for V2.0 part A (S:C4h) CAN Identifier Mask Registers 1
7 IDMSK 10 6 IDMSK 9 5 IDMSK 8 4 IDMSK 7 Description IDentifier Mask Value 0 - comparison true forced. 1 - bit comparison enabled. See Figure 43. 3 IDMSK 6 2 IDMSK 5 1 IDMSK 4 0 IDMSK 3
Bit Number
Bit Mnemonic
7-0
IDTMSK10:3
No default value after reset. Table 80. CANIDM2 Register for V2.0 part A CANIDM2 for V2.0 part A (S:C5h) CAN Identifier Mask Registers 2
7 IDMSK 2 6 IDMSK 1 5 IDMSK 0 4 Description IDentifier Mask Value 0 - comparison true forced. 1 - bit comparison enabled. See Figure 43. Reserved The values read from these bits are indeterminate. Do not set these bits. 3 2 1 0 -
Bit Number
Bit Mnemonic
7-5
IDTMSK2:0
4 -0
-
No default value after reset. Table 81. CANIDM3 Register for V2.0 part A CANIDM3 for V2.0 part A (S:C6h) CAN Identifier Mask Registers 3
7 Bit Number 7-0 6 5 Bit Mnemonic 4 Description Reserved The values read from these bits are indeterminate. 3 2 1 0 -
No default value after reset.
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Table 82. CANIDM4 Register for V2.0 part A CANIDM4 for V2.0 part A (S:C7h) CAN Identifier Mask Registers 4
7 Bit Number 6 5 Bit Mnemonic 4 Description Reserved The values read from these bits are indeterminate. Do not set these bits. Remote transmission request Mask Value 0 - comparison true forced. 1 - bit comparison enabled. Reserved The value read from this bit is indeterminate. Do not set this bit. IDentifier Extension Mask Value 0 - comparison true forced. 1 - bit comparison enabled. 3 2 RTRMSK 1 0 IDEMSK
7-3
-
2
RTRMSK
1
-
0
IDEMSK
Note:
The ID Mask is only used for reception.
No default value after reset. Table 83. CANIDM1 Register for V2.0 Part B CANIDM1 for V2.0 Part B (S:C4h) CAN Identifier Mask Registers 1
7 IDMSK 28 6 IDMSK 27 5 IDMSK 26 4 IDMSK 25 Description IDentifier Mask Value 0 - comparison true forced. 1 - bit comparison enabled. See Figure 43. 3 IDMSK 24 2 IDMSK 23 1 IDMSK 22 0 IDMSK 21
Bit Number
Bit Mnemonic
7-0
IDMSK28:21
Note:
The ID Mask is only used for reception.
No default value after reset.
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Table 84. CANIDM2 Register for V2.0 Part B CANIDM2 for V2.0 Part B (S:C5h) CAN Identifier Mask Registers 2
7 IDMSK 20 6 IDMSK 19 5 IDMSK 18 4 IDMSK 17 Description IDentifier Mask Value(1) 7-0 IDMSK20:13 0 - comparison true forced. 1 - bit comparison enabled. See Figure 43. 3 IDMSK 16 2 IDMSK 15 1 IDMSK 14 0 IDMSK 13
Bit Number
Bit Mnemonic
Note:
1. The ID Mask is only used for reception.
No default value after reset. Table 85. CANIDM3 Register for V2.0 Part B CANIDM3 for V2.0 Part B (S:C6h) CAN Identifier Mask Registers 3
7 IDMSK 12 6 IDMSK 11 5 IDMSK 10 4 IDMSK 9 Description IDentifier Mask Value 0 - comparison true forced. 1 - bit comparison enabled. See Figure 43. 3 IDMSK 8 2 IDMSK 7 1 IDMSK 6 0 IDMSK 5
Bit Number
Bit Mnemonic
7-0
IDMSK12:5
Note:
The ID Mask is only used for reception.
No default value after reset.
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Table 86. CANIDM4 Register for V2.0 Part B CANIDM4 for V2.0 Part B (S:C7h) CAN Identifier Mask Registers 4
7 IDMSK 4 6 IDMSK 3 5 IDMSK 2 4 IDMSK 1 Description IDentifier Mask Value 0 - comparison true forced. 1 - bit comparison enabled. See Figure 43. Remote transmission request Mask Value 0 - comparison true forced. 1 - bit comparison enabled. Reserved The value read from this bit is indeterminate. Do not set this bit. IDentifier Extension Mask Value 0 - comparison true forced. 1 - bit comparison enabled. 3 IDMSK 0 2 RTRMSK 1 0 IDEMSK
Bit Number
Bit Mnemonic
7-3
IDMSK4:0
2
RTRMSK
1
-
0
IDEMSK
Note:
The ID Mask is only used for reception.
No default value after reset. Table 87. CANMSG Register CANMSG (S:A3h) CAN Message Data Register
7 MSG 7 Bit Number 6 MSG 6 5 MSG 5 4 MSG 4 Description Message Data This register contains the mailbox data byte pointed at the page message object register. After writing in the page message object register, this byte is equal to the specified message location (in the mailbox) of the predefined identifier + index. If auto-incrementation is used, at the end of the data register writing or reading cycle, the mailbox pointer is auto-incremented. The range of the counting is 8 with no end loop (0, 1,..., 7, 0,...) 3 MSG 3 2 MSG 2 1 MSG 1 0 MSG 0
Bit Mnemonic
7-0
MSG7:0
No default value after reset.
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Table 88. CANTCON Register CANTCON (S:A1h) CAN Timer ClockControl
7 TPRESC 7 6 TPRESC 6 5 TPRESC 5 4 TPRESC 4 Description Timer Prescaler of CAN Timer This register is a prescaler for the main timer upper counter range = 0 to 255. See Figure 44. 3 TPRESC 3 2 TPRESC 2 1 TPRESC 1 0 TPRESC 0
Bit Number
Bit Mnemonic
7-0
TPRESC7:0
Reset Value = 00h Table 89. CANTIMH Register CANTIMH (S:ADh) CAN Timer High
7 CANGTIM 15 6 CANGTIM 14 5 CANGTIM 13 4 CANGTIM 12 Description High byte of Message Timer See Figure 44. 3 CANGTIM 11 2 CANGTIM 10 1 CANGTIM 9 0 CANGTIM 8
Bit Number 7-0
Bit Mnemonic CANGTIM15:8
Reset Value = 0000 0000b Table 90. CANTIML Register CANTIML (S:ACh) CAN Timer Low
7 CANGTIM 7 6 CANGTIM 6 5 CANGTIM 5 4 CANGTIM 4 Description Low byte of Message Timer See Figure 44. 3 CANGTIM 3 2 CANGTIM 2 1 CANGTIM 1 0 CANGTIM 0
Bit Number 7-0
Bit Mnemonic CANGTIM7:0
Reset Value = 0000 0000b
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Table 91. CANSTMPH Register CANSTMPH (S:AFh Read Only) CAN Stamp Timer High
7 TIMSTMP 15 6 TIMSTMP 14 5 TIMSTMP 13 4 TIMSTMP 12 Description High byte of Time Stamp See Figure 44. 3 TIMSTMP 11 2 TIMSTMP 10 1 0
TIMSTMP 9 TIMSTMP 8
Bit Number 7-0
Bit Mnemonic TIMSTMP15:8
No default value after reset Table 92. CANSTMPL Register CANSTMPL (S:AEh Read Only) CAN Stamp Timer Low
7 6 5 4 3 2 1 0
TIMSTMP 7 TIMSTMP 6 TIMSTMP 5 TIMSTMP 4 TIMSTMP 3 TIMSTMP 2 TIMSTMP 1 TIMSTMP 0 Bit Number 7-0 Bit Mnemonic TIMSTMP7:0 Description Low byte of Time Stamp See Figure 44.
No default value after reset Table 93. CANTTCH Register CANTTCH (S:A5h Read Only) CAN TTC Timer High
7 6 5 4 3 TIMTTC 11 2 TIMTTC 10 1 TIMTTC 9 0 TIMTTC 8
TIMTTC 15 TIMTTC 14 Bit Number 7-0
TIMTTC 13 TIMTTC 12 Description
Bit Mnemonic TIMTTC15:8
High byte of TTC Timer See Figure 44.
Reset Value = 0000 0000b Table 94. CANTTCL Register CANTTCL (S:A4h Read Only) CAN TTC Timer Low
7 TIMTTC 7 6 TIMTTC 6 5 TIMTTC 5 4 TIMTTC 4 Description Low Byte of TTC Timer See Figure 44. 3 TIMTTC 3 2 TIMTTC 2 1 TIMTTC 1 0 TIMTTC 0
Bit Number 7-0
Bit Mnemonic TIMTTC7:0
Reset Value = 0000 0000b
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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 two compare/capture modules. Its clock input can be programmed to count any of the following signals: • • • • • • • • PCA clock frequency/6 (See “clock” section) PCA clock frequency/2 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:
When the compare/capture modules are programmed in capture mode, software timer, or high speed output mode, an interrupt can be generated when the module executes its function. Both modules and the PCA timer overflow share one interrupt vector. The PCA timer/counter and compare/capture modules share Port 1 for external I/Os. These pins are listed below. If the pin 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 External I/O Pin P1.2/ECI P1.3/CEX0 P1.4/CEX1
PCA Timer
The PCA timer is a common time base for both modules (See Figure 9). The timer count source is determined from the CPS1 and CPS0 bits in the CMOD SFR ( See Table 8) and can be programmed to run at: • • • • 1/6 the PCA clock frequency. 1/2 the PCA clock frequency. The Timer 0 overflow. The input on the ECI pin (P1.2).
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Figure 46. PCA Timer/Counter
To PCA modules FPca/6 FPca/2 T0 OVF P1.2 CH CL 16-bit up counter overflow It
CIDL Idle
CPS1 CPS0
ECF
CMOD 0xD9
CF
CR
CCF1 CCF0
CCON 0xD8
The CMOD register includes three additional bits associated with the PCA. • • The CIDL bit which allows the PCA to stop during idle mode. The ECF bit which when set causes an interrupt and the PCA overflow flag CF in CCON register 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 and each module. • • • The CR bit must be set to run the PCA. The PCA is shut off by clearing this bit. The CF bit is set when the PCA counter overflows and an interrupt will be generated if the ECF bit in CMOD register is set. The CF bit can only be cleared by software. The CCF0:1 bits are the flags for the modules (CCF0 for module0...) and are set by hardware when either a match or a capture occurs. These flags also can be cleared by software.
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PCA Modules
Each one of the two 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.
Each module in the PCA has a special function register associated with it (CCAPM0 for module 0 ...). The CCAPM0:1 registers contain the bits that control the mode that each module will operate in. • • • The ECCF bit enables the CCF flag in the CCON register to generate an interrupt when a match or compare occurs in the associated module. The PWM bit enables the pulse width modulation mode. The TOG bit 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 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 two bits CAPN and CAPP in CCAPMn register 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. The bit ECOM in CCAPM register when set enables the comparator function.
•
•
•
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PCA Interrupt
Figure 47. PCA Interrupt System
CF PCA Timer/Counter CR CCF1 CCF0 CCON 0xD8
Module 0
Module 1
To Interrupt
ECF
CMOD.0
ECCFn
CCAPMn.0
EC
IEN0.6
EA
IEN0.7
PCA Capture Mode
To use one of the PCA modules in 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.
Figure 48. PCA Capture Mode PCA Counter
CH (8-bits) CL (8-bits)
CEXn n = 0, 1
CCAPnH CCAPnL
CCFn CCON Reg 7
PCA Interrupt Request
0CAPPnCAPNn000ECCFn 0 CCAPMn Register (n = 0, 1)
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16-bit Software Timer 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.
Figure 49. PCA 16-bit Software Timer and High Speed Output Mode
PCA Counter CH CL (8 bits) (8 bits) Compare/Capture Module CCAPnL CCAPnH (8 bits) (8 bits) Match 16-bit Comparator Enable CCFn CCON reg Toggle CEXn PCA Interrupt Request
ECOMn0 0 MATn TOGn0 ECCFn 0 CCAPMn Register (n = 0, 1) For software Timer mode, set ECOMn and MATn. For high speed output mode, set ECOMn, MATn and TOGn.
7 “0” Reset Write to CCAPnL Write to CCAPnH “1”
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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. Figure 50. PCA High Speed Output Mode
CCON CF Write to CCAPnH Write to CCAPnL “0” “1” Reset PCA IT CCAPnH Enable 16 bit comparator CCAPnL Match CR CCF1 CCF0 0xD8
CH
CL
CEXn
PCA counter/timer CCAPMn, n = 0 to 1 0xDA to 0xDE
ECOMn CAPPn CAPNn MATn TOGn PWMn ECCFn
Pulse Width Modulator Mode
All the PCA modules can be used as PWM outputs. The output frequency depends on the source for the PCA timer. All the modules will have the same output frequency 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 it, the output will be high. When CL overflows from FF to 00, CCAPLn is reloaded with the value in CCAPHn. the allows the PWM to be updated without glitches. The PWM and ECOM bits in the module’s CCAPMn register must be set to enable the PWM mode.
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Figure 51. PCA PWM Mode CCAPnH
CL rolls over from FFh TO 00h loads CCAPnH contents into CCAPnL
CCAPnL “0” CL < CCAPnL CL (8 bits) 8-bit Comparator CEX CL >= CCAPnL “1”
ECOMn
CCAPMn.6
PWMn
CCAPMn.1
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PCA Registers
Table 95. CMOD Register CMOD (S:D9h) PCA Counter Mode Register
7 CIDL 6 Bit Mnemonic 5 4 3 2 CPS1 1 CPS0 0 ECF
Bit Number
Description PCA Counter Idle Control bit Clear to let the PCA run during Idle mode. Set to stop the PCA when Idle mode is invoked. 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. EWC Count Pulse Select bits CPS1 CPS0 Clock source 0 0 Internal Clock, FPca/6 0 1 Internal Clock, FPca/2 1 0 Timer 0 overflow 1 1 External clock at ECI/P1.2 pin (Max. Rate = FPca/4) Enable PCA Counter Overflow Interrupt bit Clear to disable CF bit in CCON register to generate an interrupt. Set to enable CF bit in CCON register to generate an interrupt.
7
CIDL
6
-
5
-
4
-
3
-
2-1
CPS1:0
0
ECF
Reset Value = 0XXX X000b
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Table 96. CCON Register CCON (S:D8h) PCA Counter Control Register
7 CF Bit Number 6 CR 5 Bit Mnemonic 4 Description PCA Timer/Counter Overflow flag Set by hardware when the PCA Timer/Counter rolls over. This generates a PCA interrupt request if the ECF bit in CMOD register is set. Must be cleared by software. PCA Timer/Counter Run Control bit Clear to turn the PCA Timer/Counter off. Set to turn the PCA Timer/Counter on. Reserved The value read from these bist are indeterminate. Do not set these bits. PCA Module 1 Compare/Capture Flag Set by hardware when a match or capture occurs. This generates a PCA interrupt request if the ECCF 1 bit in CCAPM 1 register is set. Must be cleared by software. PCA Module 0 Compare/Capture Flag Set by hardware when a match or capture occurs. This generates a PCA interrupt request if the ECCF 0 bit in CCAPM 0 register is set. Must be cleared by software. 3 2 1 CCF1 0 CCF0
7
CF
6
CR
5-2
-
1
CCF1
0
CCF0
Reset Value = 00xx xx00b
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Table 97. CCAPnH Registers CCAP0H (S:FAh) CCAP1H (S:FBh) PCA High Byte Compare/Capture Module n Register (n=0..1)
7 CCAPnH 7 6 CCAPnH 6 5 CCAPnH 5 4 CCAPnH 4 Description High byte of EWC-PCA comparison or capture values 3 CCAPnH 3 2 CCAPnH 2 1 CCAPnH 1 0 CCAPnH 0
Bit Number 7:0
Bit Mnemonic CCAPnH 7:0
Reset Value = 0000 0000b Table 98. CCAPnL Registers CCAP0L (S:EAh) CCAP1L (S:EBh) PCA Low Byte Compare/Capture Module n Register (n=0..1)
7 CCAPnL 7 6 CCAPnL 6 5 CCAPnL 5 4 CCAPnL 4 Description Low byte of EWC-PCA comparison or capture values 3 CCAPnL 3 2 CCAPnL 2 1 CCAPnL 1 0 CCAPnL 0
Bit Number 7:0
Bit Mnemonic CCAPnL 7:0
Reset Value = 0000 0000b
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Table 99. CCAPMn Registers CCAPM0 (S:DAh) CCAPM1 (S:DBh) PCA Compare/Capture Module n Mode registers (n=0..1)
7 Bit Number 7 6 ECOMn 5 CAPPn 4 CAPNn Description Reserved The Value read from this bit is indeterminate. Do not set this bit. Enable Compare Mode Module x bit Clear to disable the Compare function. Set to enable the Compare function. The Compare function is used to implement the software Timer, the high-speed output, the Pulse Width Modulator (PWM) and the Watchdog Timer (WDT). Capture Mode (Positive) Module x bit Clear to disable the Capture function triggered by a positive edge on CEXx pin. Set to enable the Capture function triggered by a positive edge on CEXx pin Capture Mode (Negative) Module x bit Clear to disable the Capture function triggered by a negative edge on CEXx pin. Set to enable the Capture function triggered by a negative edge on CEXx pin. Match Module x bit Set when a match of the PCA Counter with the Compare/Capture register sets CCFx bit in CCON register, flagging an interrupt. Toggle Module x bit The toggle mode is configured by setting ECOMx, MATx and TOGx bits. Set when a match of the PCA Counter with the Compare/Capture register toggles the CEXx pin. Pulse Width Modulation Module x Mode bit Set to configure the module x as an 8-bit Pulse Width Modulator with output waveform on CEXx pin. Enable CCFx Interrupt bit Clear to disable CCFx bit in CCON register to generate an interrupt request. Set to enable CCFx bit in CCON register to generate an interrupt request. 3 MATn 2 TOGn 1 PWMn 0 ECCFn
Bit Mnemonic -
6
ECOMn
5
CAPPn
4
CAPNn
3
MATn
2
TOGn
1
PWMn
0
ECCFn
Reset Value = X000 0000b
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Table 100. CH Register CH (S:F9h) PCA Counter Register High value
7 CH 7 Bit Number 7:0 6 CH 6 5 CH 5 Bit Mnemonic CH 7:0 4 CH 4 Description High byte of Timer/Counter 3 CH 3 2 CH 2 1 CH 1 0 CH 0
Reset Value = 0000 00000b Table 101. CL Register CL (S:E9h) PCA counter Register Low value
7 CL 7 Bit Number 7:0 6 CL 6 5 CL 5 Bit Mnemonic CL0 7:0 4 CL 4 Description Low byte of Timer/Counter 3 CL 3 2 CL 2 1 CL 1 0 CL 0
Reset Value = 0000 00000b
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Analog-to-Digital Converter (ADC)
Th is se ctio n d esc rib es th e o n-ch ip 10 -b it a nalog -to- digital con verte r of th e T89C51CC02. Eight ADC channels are available for sampling of the external sources AN0 to AN7. An analog multiplexer allows the single ADC converter to select one from the 8 ADC channels as ADC input voltage (ADCIN). ADCIN is converted by the 10-bitcascaded potentiometric ADC. Two modes of conversion are available: - Standard conversion (8 bits). - Precision conversion (10 bits). For the precision conversion, set bit PSIDLE in ADCON register and start conversion. The device is in a pseudo-idle mode, the CPU does not run but the peripherals are always running. This mode allows digital noise to be as low as possible, to ensure high precision conversion. For this mode it is necessary to work with end of conversion interrupt, which is the only way to wake the device up. If another interrupt occurs during the precision conversion, it will be served only after this conversion is completed.
Features
• • • • • • • • • •
8 channels with multiplexed inputs 10-bit cascaded potentiometric ADC Conversion time 16 micro-seconds (typ.) Zero Error (offset) ± 2 LSB max Positive External Reference Voltage Range (VAREF) 2.4 to 3.0-volt (typ.) ADCIN Range 0 to 3-volt Integral non-linearity typical 1 LSB, max. 2 LSB Differential non-linearity typical 0.5 LSB, max. 1 LSB Conversion Complete Flag or Conversion Complete Interrupt Selectable ADC Clock
ADC Port1 I/O Functions
Port 1 pins are general I/O that are shared with the ADC channels. The channel select bit in ADCF register define which ADC channel/port1 pin will be used as ADCIN. The remaining ADC channels/port1 pins can be used as general purpose I/O or as the alternate function that is available. A conversion launched on a channel which are not selected on ADCF register will not have any effect.
VAREF
VAREF should be connected to a low impedance point and must remain in the range specified VAREF absolute maximum range (See section “AC-DC”). . If the ADC is not used, it is recommended to tie VAREF to VAGND.
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Figure 52. ADC Description
ADCON.5 ADCON.3
ADEN
ADSST
ADCON.4
ADC CLOCK
ADEOC
CONTROL
ADC Interrupt Request EADC
IEN1.1
AN0/P1.0 AN1/P1.1 AN2/P1.2 AN3/P1.3 AN4/P1.4 AN5/P1.5 AN6/P1.6 AN7/P1.7
000 001 010 011 100 101 110 111
Cai Rai
ADCIN
8
+ SAR 2
ADDH ADDL
AVSS
Sample and Hold R/2R DAC
10
SCH2
ADCON.2
SCH1
ADCON.1
SCH0
ADCON.0
VAREF VAGND
Figure 53 shows the timing diagram of a complete conversion. For simplicity, the figure depicts the waveforms in idealized form and do not provide precise timing information. For ADC characteristics and timing parameters refer to the section “AC Characteristics” of this datasheet. Figure 53. Timing Diagram CLK ADEN
TSETUP
ADSST
TCONV
ADEOC
Note: Tsetup min, see the AC Parameter for A/D conversion. Tconv = 11 clock ADC = 1sample and hold + 10-bit conversion The user must ensure that Tsetup time between setting ADEN and the start of the first conversion.
ADC Converter Operation
A start of single A/D conversion is triggered by setting bit ADSST (ADCON.3). After completion of the A/D conversion, the ADSST bit is cleared by hardware. The end-of-conversion flag ADEOC (ADCON.4) is set when the value of conversion is available in ADDH and ADDL, it must be cleared by software. If the bit EADC (IEN1.1) is set, an interrupt occur when flag ADEOC is set (See Figure 55). Clear this flag for rearming the interrupt.
Note: Always leave Tsetup time before starting a conversion unless ADEN is permanently high. In this case one should wait Tsetup only before the first conversion
127
4126J–CAN–05/06
The bits SCH0 to SCH2 in ADCON register are used for the analog input channel selection. Table 102. Selected Analog input
SCH2 0 0 0 0 1 1 1 1 SCH1 0 0 1 1 0 0 1 1 SCH0 0 1 0 1 0 1 0 1 Selected Analog Input AN0 AN1 AN2 AN3 AN4 AN5 AN6 AN7
Voltage Conversion
When the ADCIN is equals to VAREF the ADC converts the signal to 3FFh (full scale). If the input voltage equals VAGND, the ADC converts it to 000h. Input voltage between VAREF and VAGND are a straight-line linear conversion. All other voltages will result in 3FFh if greater than VAREF and 000h if less than VAGND. Note that ADCIN should not exceed VAREF absolute maximum range (See section “AC-DC”).
Clock Selection
The ADC clock is the same as CPU. The maximum clock frequency is defined in the DC parmeter for A/D converter. A prescaler is featured (ADCCLK) to generate the ADC clock from the oscillator frequency. if PRS = 0 then FADC = Fperiph / 64 if PRS > 0 then FADC = Fperiph / 2 x PRS
Figure 54. A/D Converter Clock
CPU CLOCK
÷2
Prescaler ADCLK
ADC Clock
A/D Converter
CPU Core Clock Symbol
ADC Standby Mode
When the ADC is not used, it is possible to set it in standby mode by clearing bit ADEN in ADCON register. In this mode the power dissipation is reduced.
128
AT/T89C51CC02
4126J–CAN–05/06
AT/T89C51CC02
IT ADC Management
An interrupt end-of-conversion will occurs when the bit ADEOC is activated and the bit EADC is set. For re-arming the interrupt the bit ADEOC must be cleared by software. Figure 55. ADC interrupt structure
ADEOC
ADCON.2
ADCI EADC
IEN1.1
Routine Examples
1. Configure P1.2 and P1.3 in ADC channels // configure channel P1.2 and P1.3 for ADC ADCF = 0Ch // Enable the ADC ADCON = 20h 2. Start a standard conversion // The variable ’channel’ contains the channel to convert // The variable ’value_converted’ is an unsigned int // Clear the field SCH[2:0] ADCON &= F8h // Select channel ADCON |= channel // Start conversion in standard mode ADCON |= 08h // Wait flag End of conversion while((ADCON & 01h)!= 01h) // Clear the End of conversion flag ADCON &= EFh // read the value value_converted = (ADDH
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