/************************************************************* I2C.C This program contains I2C routines. Written for Hi-Tech PICC compiler vX.XX **************************************************************/ #include #include "I2C.H" /******************************************************************** Function Name: OpenI2C Return Value: void Parameters: SSP peripheral setup bytes Description: This function sets up the SSP module on a PIC16 device for use with a Microchip I2C EEPROM device or I2C bus device. ********************************************************************/ void OpenI2C(unsigned char sync_mode, unsigned char slew) { SSPSTAT &= 0x00; // power on state 3f SSPCON = 0x00; // power on state SSPCON |= sync_mode; // select serial mode CKP = 1; // Releases clock (no clock stretching) SSPEN = 1; // enable synchronous serial port } /************************************************************* Function Name: I2CStart Return Value: void Parameters: void Description: Sends an I2C Start bit **************************************************************/ void I2CStart() { //Precondition SCL and SDA SCL_L; //SCL LOW just in case it is not already LOW SDA_H; //SDA HIGH SCL_H; //SCL HIGH //START Condition SDA_L; while(!START); //wait for START while(!SSPIF); //Wait for flag to set SSPIF = 0; } /************************************************************* Function Name: I2CReStart Return Value: void Parameters: void Description: Sends an I2C Re-start bit **************************************************************/ void I2CReStart() { //Precondition SCL and SDA SCL_L; //SCL LOW just in case it is not already LOW SDA_H; //SDA HIGH SCL_H; //SCL HIGH //START Condition SDA_L; while(!START); //wait for START while(!SSPIF); //Wait for flag to set SSPIF = 0; } /******************************************************************** Function Name: AckI2C Return Value: void Parameters: void Description: Initiate ACK bus condition. ********************************************************************/ void ACKI2C(void) { ACK; //Start ACK sequence } /************************************************************* Function Name: WaitForACK Return Value: Returns 0 if ACK; returns -1 if timeout Parameters: void Description: Waits for an ACK from the slave device **************************************************************/ unsigned char WaitForACK() { unsigned char n = 0; SDA_H; //Float SDA SCL_H; //Starts ACK pulse while(SDA_LEVEL) //Waits for slave ACK { n++; if(!n) return -1; //return -1 on timeout } SCL_L; //Ends ACK pulse return 0; } /************************************************************* Function Name: I2CStop Return Value: void Parameters: void Description: Sends a Stop bit **************************************************************/ void I2CStop() { SSPIF = 0; //Precondition SCL and SDA SCL_L; //SCL LOW just in case it is not already LOW SDA_L; //SDA LOW SCL_H; //SCL HIGH SDA_H; //Stop condition while(!STOP); //wait for STOP while(!SSPIF); //Wait for flag to set SSPIF = 0; } /******************************************************************** Function Name: WriteI2C Return Value: Status Parameters: Single data byte for I2C bus. Description: This routine writes a single byte to the I2C bus. ********************************************************************/ unsigned char WriteI2C( unsigned char data_out ) { unsigned char n; SCL_L; //SCL LOW... just in case for(n=0; n<8; n++) { if((data_out << n) & 0x80) { SDA_H; SCL_H; SCL_L; } else { SDA_L; SCL_H; SCL_L; } } return 0; } /******************************************************************** Function Name: ReadI2C Return Value: Read value Parameters: void Description: Read single byte from I2C bus. ********************************************************************/ unsigned char ReadI2C(void) { unsigned char n, data_in; data_in = 0; for(n=0; n<8; n++) { SCL_H; data_in = ((data_in + SDA_LEVEL) << 1); SCL_L; } data_in = data_in >> 1; return(data_in); } /************************************************************* Function Name: nACK Return Value: void Parameters: void Description: Sends an ACK bit **************************************************************/ void nACK() { NACK; //Start ACK sequence } /************************************************************* Function Name: I2CDataReady Return Value: BF bit Parameters: void Description: Sends a Stop bit **************************************************************/ unsigned char I2CDataReady() { if (BF) // test if buffer full bit is set return ( +1 ); // data in SSPBUF register else return ( 0 ); // no data in SSPBUF register }