I2C2 call Init ; Initialize device call ByteRead ; Byte Read operation RETURN Init bcf STATUS,RP1 ; Select Bank 01 bsf STATUS,RP0 movlw b'00011000' movwf TRISC ; Set PORTC to all inputs clrf SSPSTAT ; Disable SMBus inputs bsf SSPSTAT,SMP ; Disable slew rate control movlw d'99' ; Load 0x18 into WREG movwf SSPADD ; Setup 100 kHz I2C clock clrf SSPCON2 ; Clear control bits bcf STATUS,RP0 ; Select Bank 00 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 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 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 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 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 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 CELZIUS ; 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 ByteRead call BSTART ; Generate Start condition ; Send control byte bcf STATUS,RP0 ; Select Bank 00 movlw B'10010000' ; 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 0x5A for word address movwf datao ; Copy to datao for output call TX ; Send high byte to device call BRESTART ; Generate Restart condition ; Send control byte bcf STATUS,RP0 ; Select Bank 00 movlw B'10010001' ; 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 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