TCN75A Code

/* Datasheet: http://ww1.microchip.com/downloads/en/devicedoc/21935a.pdf */

void main(void){

    setup_init();
    lcd_init();
    tcn75_init();

    stdout = _H_USER;               // Set STDOUT to user defined function

    while(1){

        lcd_set_cursor(2, 1);
        printf("%4d", read_tcn75());

        Delay10KTCYx(200);          // Delay
    }

}

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

    SWStartI2C();               // Start
    SWPutcI2C(0x90);            // Address byte (write)
    SWAckI2C();
    SWPutcI2C(0x00);            // Pointer (temp)
    SWAckI2C();
    SWRestartI2C();             // Restart

    SWPutcI2C(0x91);            // Address byte (read)
    SWAckI2C();
    msb = SWGetcI2C();          // Get MSB
    SWAckI2C();
    lsb = SWGetcI2C();          // Get LSB
    SWNotAckI2C();

    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
*/

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