LIST P=16F877A ;*******************RAM register definitions********************** datai equ 20h ; Data input byte buffer datao equ 21h ; Data output byte buffer bytecount equ 22h ; Counter for byte loops pollcnt equ 23h ; Counter for polling loops loops equ 24h ; Delay loop counter loops2 equ 25h ; Delay loop counter T1 equ 26h T2 equ 27h ;*******************Macro definitions***************************** WRITE_ADDR equ b'10100000' ; Control byte for write operations READ_ADDR equ b'10100001' ; Control byte for read operations ;*******************Include file********************************** include "p16f877a.inc" ; Include file for a PIC16F877A errorlevel -302 ; Suppress message 302 from list file ;***************************************************************** org 0x000 ; Set the reset vector goto start ; Go to the beginning of main ;*******************Begin Main Program**************************** start call Init ; Initialize device call ByteWrite ; Byte Write operation call Kesleltetes call ByteRead ; Byte Read operation call Kiertekeles nop goto $-1 ; Loop here forever ;*******************Initialization subroutine********************* ; This routine initializes the MSSP module ; for I2C Master mode, with a 100 kHz clock. ;***************************************************************** Init bcf STATUS,RP1 ; Select Bank 01 bsf STATUS,RP0 MOVLW B'00000000' ;PORTD MIND KIMENET MOVWF TRISD movlw b'11111111' movwf TRISC ; Set PORTC to all inputs clrf SSPSTAT ; Disable SMBus inputs bsf SSPSTAT,SMP ; Disable slew rate control movlw 0x9 ; Load 0x18 into WREG /10 MHz-es kvarcnál, 4 MHz-esnél = 9 movwf SSPADD ; Setup 100 kHz I2C clock clrf SSPCON2 ; Clear control bits bcf STATUS,RP0 ; Select Bank 00 clrf PORTD movlw b'00101000' movwf SSPCON ; Enable SSP, select I2C Master mode bcf PIR1,SSPIF ; Clear SSP interrupt flag bcf PIR2,BCLIF ; Clear Bit Collision flag retlw 0 ;*******************Byte write test subroutine******************** ; This routine tests the byte write feature ; of the serial EEPROM device. It will write ; 1 byte of data to the device at address 0x0000. ;***************************************************************** ByteWrite call BSTART ; Generate Start condition ; Send control byte bcf STATUS,RP0 ; Select Bank 00 movlw WRITE_ADDR ; Load control byte for write movwf datao ; Copy to datao for output call TX ; Send control byte to device ; Send word address high byte bcf STATUS,RP0 ; Select Bank 00 movlw 0x00 ; Load 0x00 for word address movwf datao ; Copy to datao for output call TX ; Send word address low byte bcf STATUS,RP0 ; Select Bank 00 movlw 0x00 ; Load 0x00 for word address movwf datao ; Copy to datao for output call TX ; Send word address to device ; Send data byte bcf STATUS,RP0 ; Select Bank 00 movlw 0xAA ; Load 0xAA for data byte AA=B'10101010' movwf datao ; Copy to datao for output call TX ; Send data byte to device call BSTOP ; Generate Stop condition ; call Poll ; Poll for write completion retlw 0 ;*******************Byte read test subroutine********************* ; This routine tests the byte read feature ; of the serial EEPROM device. It will read ; 1 byte of data at address 0x0000 from the device. ;***************************************************************** ByteRead call BSTART ; Generate Start condition ; Send control byte bcf STATUS,RP0 ; Select Bank 00 movlw WRITE_ADDR ; Load control byte for write movwf datao ; Copy to datao for output call TX ; Send control byte to device ; Send word address high byte bcf STATUS,RP0 ; Select Bank 00 movlw 0x00 ; Load 0x00 for word address movwf datao ; Copy to datao for output call TX ; Send high byte to device ; Send word address low byte bcf STATUS,RP0 ; Select Bank 00 movlw 0x00 ; Load 0x00 for word address movwf datao ; Copy to datao for output call TX ; Send word address to device call BRESTART ; Generate Restart condition ; Send control byte bcf STATUS,RP0 ; Select Bank 00 movlw READ_ADDR ; Load control byte for read movwf datao ; Copy to datao for output call TX ; Send control byte to device ; Read data byte bsf STATUS,RP0 ; Select Bank 01 bsf SSPCON2,ACKDT ; Select to send NO ACK bit call RX ; Read data byte from device call BSTOP ; Generate Stop condition retlw 0 ;***************************************************************** ; ; A kiküldött és a vett adat összehasonlítása majd kijelzése ; PORTD 0. bit = 1 az adatok különbözőek ; PORTD 1. bit = 1 az adatok megegyeznek ; ;***************************************************************** Kiertekeles bcf STATUS,Z movf datai,W sublw B'10101010' btfss STATUS,Z goto Kijelzes0 goto Kijelzes1 Kijelzes0 bsf PORTD,0 goto Kilep Kijelzes1 bsf PORTD,1 Kilep return ;*******************Start bit subroutine************************** ; This routine generates a Start condition ; (high-to-low transition of SDA while SCL ; is still high. ;***************************************************************** BSTART bcf STATUS,RP1 bcf STATUS,RP0 ; Select Bank 00 bcf PIR1,SSPIF ; Clear SSP interrupt flag bsf STATUS,RP0 ; Select Bank 01 bsf SSPCON2,SEN ; Generate Start condition bcf STATUS,RP0 ; Select Bank 00 bstart_wait btfss PIR1,SSPIF ; Check if operation completed goto bstart_wait ; If not, keep checking retlw 0 ;*******************Restart bit subroutine************************** ; This routine generates a Repeated Start ; condition (high-to-low transition of SDA ; while SCL is still high. ;***************************************************************** BRESTART bcf STATUS,RP1 bcf STATUS,RP0 ; Select Bank 00 bcf PIR1,SSPIF ; Clear SSP interrupt flag bsf STATUS,RP0 ; Select Bank 01 bsf SSPCON2,RSEN ; Generate Restart condition bcf STATUS,RP0 ; Select Bank 00 brestart_wait btfss PIR1,SSPIF ; Check if operation completed goto brestart_wait ; If not, keep checking retlw 0 ;*******************Stop bit subroutine*************************** ; This routine generates a Stop condition ; (low-to-high transition of SDA while SCL ; is still high. ;***************************************************************** BSTOP bcf STATUS,RP1 bcf STATUS,RP0 ; Select Bank 00 bcf PIR1,SSPIF ; Clear SSP interrupt flag bsf STATUS,RP0 ; Select Bank 01 bsf SSPCON2,PEN ; Generate Stop condition bcf STATUS,RP0 ; Select Bank 00 bstop_wait btfss PIR1,SSPIF ; Check if operation completed goto bstop_wait ; If not, keep checking retlw 0 ;*******************Data transmit subroutine********************** ; This routine transmits the byte of data ; stored in 'datao' to the serial EEPROM ; device. Instructions are also in place ; to check for an ACK bit, if desired. ; Just replace the 'goto' instruction, ; or create an 'ackfailed' label, to provide ; the functionality. ;***************************************************************** TX bcf STATUS,RP1 bcf STATUS,RP0 ; Select Bank 00 bcf PIR1,SSPIF ; Clear SSP interrupt flag movf datao,W ; Copy datao to WREG movwf SSPBUF ; Write byte out to device tx_wait btfss PIR1,SSPIF ; Check if operation completed goto tx_wait ; If not, keep checking ; bsf STATUS,RP0 ; Select Bank 01 ; btfsc SSPCON2,ACKSTAT ; Check if ACK bit was received ; goto ackfailed ; This executes if no ACK received retlw 0 ;*******************Data receive subroutine*********************** ; This routine reads in one byte of data from ; the serial EEPROM device, and stores it in ; 'datai'. It then responds with either an ; ACK or a NO ACK bit, depending on the value ; of 'ACKDT' in 'SSPCON2'. ;***************************************************************** RX bcf STATUS,RP1 bcf STATUS,RP0 ; Select Bank 00 bcf PIR1,SSPIF ; Clear SSP interrupt flag bsf STATUS,RP0 ; Select Bank 01 bsf SSPCON2,RCEN ; Initiate reception of byte bcf STATUS,RP0 ; Select Bank 00 rx_wait btfss PIR1,SSPIF ; Check if operation completed goto rx_wait ; If not, keep checking movf SSPBUF,W ; Copy byte to WREG movwf datai ; Copy WREG to datai bcf PIR1,SSPIF ; Clear SSP interrupt flag bsf STATUS,RP0 ; Select Bank 01 bsf SSPCON2,ACKEN ; Generate ACK/NO ACK bit bcf STATUS,RP0 ; Select Bank 00 rx_wait2 btfss PIR1,SSPIF ; Check if operation completed goto rx_wait2 ; If not, keep checking retlw 0 ;*******************Acknowledge Polling subroutine**************** ; This subroutine polls the EEPROM device ; for an ACK bit, which indicates that the ; internal write cycle has completed. Code ; is in place for a timeout routine, just ; uncomment the 'goto TimedOut' line, and ; provide a 'TimedOut' label. ;***************************************************************** Poll bcf STATUS,RP0 ; Select Bank 00 movlw .40 movwf pollcnt ; Set max polling times to 40 polling call BRESTART ; Generate start bit bcf STATUS,RP0 ; Select Bank 00 movlw WRITE_ADDR ; Now send the control byte movwf datao ; Copy control byte to buffer call TX ; Output control byte to device bsf STATUS,RP0 ; Select Bank 01 btfss SSPCON2,ACKSTAT ; Was the ACK bit low? goto exitpoll ; If yes, stop polling ; If no, check if polled 40 times bcf STATUS,RP0 ; Select Bank 00 decfsz pollcnt,F ; Is poll counter down to zero? goto polling ; If no, poll again ; goto TimedOut ; If yes, part didn't respond ; in time, so take action exitpoll call BSTOP ; Generate stop bit retlw 0 ;***************************************************************** ; ; 6 ms késleltetés az írás és az olvasás között ; ;***************************************************************** Kesleltetes MOVLW d'255' MOVWF T1 DEL MOVLW d'8' MOVWF T2 DEL1 DECFSZ T2,f GOTO DEL1 DECFSZ T1,f GOTO DEL RETURN END