Post by thread:I2C Slave-transmit routine problem

Hi and thenks for your attention, This is my interrupt service routine (except for push and pop procedure): btfss PIR1,3 ; SSPIF goto EXIT ;-------------------------------------------------------------------- ; Interrupt service routine ; I2C ;-------------------------------------------------------------------- service_int bsf STATUS,RP0 ; Banck 1 btfss SSPSTAT,5 ; = 0 last byte -->ADDR goto Access ; bcf STATUS,RP0 ; Bank 0 btfsc I2C_reg,TR_RC ; my SSPSTAT,5 RAM copy goto rd_dat ; Master red data goto wr_dat ; Master wrote data rd_dat movf DATAO_flag,W ; load data to transmit(SLAVE-TRANSMIT) movwf SSPBUF bsf SSPCON,CKP ;enable CLK goto IntOut ; Exit wr_dat movf SSPBUF,W ;Load data in W (e reset BF) movwf DATAI ; dato stored in buffer DATAI goto run_DATAI ; Stores in proper way the data Access btfsc SSPSTAT,2 ; if =1 SLAVE-TRANSMIT =0 SLAVE-RECEIVE goto rd_adr ; follow Master read-access (SLAVE-TRANSMIT) goto wr_adr ; follow Master write-access (SLAVE-RECEIVE) wr_adr bcf STATUS,RP0 ; Bank 0 bcf I2C_reg,TR_RC ; copy R/W_ bit in I2C_reg (=0 SLAVE-RECEIVE) movf SSPBUF,W ; read SSPBUF e reset BF goto IntOut ; Exit without storing data rd_adr bcf STATUS,RP0 ; Bank 0 bsf I2C_reg,TR_RC ; copy R/W_ bit in I2C_reg (=1 SLAVE-TRANSMIT) movf DATAO_stato,W ; load data read for transmission (SLAVE-TRANSMIT) movwf SSPBUF bsf SSPCON,CKP ;enable CLK goto IntOut ; Exit IntOut bcf PIR1,3 ; erases SSP flag interrupt bsf STATUS,RP0 ; Bank 1 bsf PIE1,3 ; Re-enable SSP interrupt bcf STATUS,RP0 ; Bank 0 Main program ........ movlw B'00110110' ; Interrupt ogni Byte movwf SSPCON movlw B'00011000' ; RC3,RC4 tristate per SSP movwf TRISC ; bsf STATUS,RP0 ; bank 1 movlw B'00001000' movwf PIE1 movlw B'10100100' ; ADDRESS of this device movwf SSPADD bcf STATUS,RP0 ; bank 0 movlw B'11000000' movwf INTCON Could you see some evident mistake? When I try to read from PIC device a byte, It acks first address byte, but after that it pulls down SCL, and it doesn't send the byte, although I have enabled the serial clock setting CLK bit in SSPCON. Then I need to reset MCU to restart I2C comunication. Thanks Paolo Marras AIRLAB (Artificial Intelligence and Robotics LAB) Electronics and Information department Politecnico of Milan