TCN75A I2C Code

#include "tcn75a.h"
#include <p18f2458.h>
#include <delays.h>

#define SCL_TRIS TRISBbits.TRISB1
#define SDA_TRIS TRISBbits.TRISB0

#define SCL LATBbits.LATB1
#define SDA LATBbits.LATB0

int read_tcn75(void){
    int data;
    short msb, lsb;

    SWStartI2C();               // Start

    SWPutcI2C(0x91);            // Address byte (read)
    SWAckI2C();             // Receive ACK
    msb = SWGetcI2C();          // Get MSB
    i2csendack();               // Send ACK
    lsb = SWGetcI2C();          // Get LSB
    i2csendnack();              // Send NACK

    SWStopI2C();                // Stop

//  data = lsb | (msb << 8);
    return lsb;             // Always returns 255, MSB is returned as expected
}

void tcn75_init(void){
/*
00 - temp
01 - config (0x60)
10 - hyst
11 - temp limit
*/

    // Setup Config reg for 12bit A/D conversion
    SWStartI2C();               // Start
    SWPutcI2C(0x90);            // Address byte (write)
    SWAckI2C();
    SWPutcI2C(0x01);            // Pointer (config)
    SWAckI2C();
    SWPutcI2C(0x60);            // Data (12bit A/D conversion)
    SWAckI2C();
    SWStopI2C();                // Stop

    // Set pointer to temperature reg
    SWStartI2C();               // Start
    SWPutcI2C(0x90);            // Address byte (write)
    SWAckI2C();
    SWPutcI2C(0x00);            // Pointer (temp)
    SWAckI2C();
    SWStopI2C();                // Stop
}

/**** Code from Mike Pierce's Routines with delays calculated for 48MHz FOSC ****/

void i2csendack(void)
{
 SDA=0;
 SDA_TRIS=0; //-- Send ACK
 Delay10TCYx(24);
 i2cclock(); //-- Pulse the clock
 SDA_TRIS=1; //-- Release ACK
 Delay10TCYx(24);
}

void i2csendnack(void)
{
 SDA=0;
 SDA_TRIS=1; //-- Send NACK
 Delay10TCYx(24);
 i2cclock(); //-- Pulse the clock
 SDA_TRIS=1; //-- Release ACK
 Delay10TCYx(24);
}

void i2cclock(void)
{
 Delay10TCYx(24);       //-- Minimum Clock Low Time
 SCL_TRIS=1;              //-- Release clock
 Delay100TCYx(12);        //-- Minimum Clock High Time
// SCL = 0;
 SCL_TRIS=0;               //-- Lower the clock
 Delay100TCYx(12);         //-- Minimum Clock Low Time
}