File content as of revision 2:d9fa8ce1b14e:

#include "mbed.h"

// Read temperature from MAX1363 3-channel ADC

I2C i2c(PB_9 , PB_8);
DigitalOut Relay(D7);
Serial pc(SERIAL_TX, SERIAL_RX);

char buffer[]={'0','0','0','0','0','\0'};
char ch;
double SetTemp=0;
float x=0;

// address information for the Serenity temperature sensor device
const int SLAVE_ADDRESS = 0x34 << 1;

// MAX1363 registers
const unsigned char MAX1363_CONFIG_REG = 0x03;  // single-ended inputs, read CH0-CH1 only
const unsigned char MAX1363_SETUP_REG  = 0xF2;  // AIN3=output, INT REF always on

// MAX1363 high byte format (byte 2 is D7-D0)
const unsigned char MAX1363_VALID_MASK = 0x90;      // HIGH bit and 12/10 bit should always be 1
const unsigned char MAX1363_HIGH_DATA_MASK = 0x0F;

// channel address (0-3) is in CH1/CH0 (bits 5/6)
const unsigned char MAX1363_CHANNEL_MASK = 0x60;
const unsigned char MAX1363_CHANNEL_SHIFT = 5;

/** conversion factors */
const float CONV_COEFF_A3 = 4.39403;
const float CONV_COEFF_A2 = -11.15;
const float CONV_COEFF_A1 = 36.4955;
const float CONV_COEFF_A0 = 266.909;

const int CONV_N = 12;
const float CONV_VREF = 2.048;

const float CONV_K_TO_C = -272.15;

float AdcToC(unsigned int _adc)
{
    float d = CONV_VREF * _adc / (1L << CONV_N);
    float d2 = d*d;
    float d3 = d2*d;
    float temp_k = (CONV_COEFF_A3 * d3) +
        (CONV_COEFF_A2 * d2) +
        (CONV_COEFF_A1 * d) +
        CONV_COEFF_A0;
    return temp_k + CONV_K_TO_C;
}

void callback(){
if (pc.readable()==1){
        for (int index=0; index<5; index=index+1){
            ch=pc.getc();
            buffer[index]=ch;
        }
        SetTemp= atof(buffer);
return;
}
}

int main() {
    pc.baud(115200);
    
    pc.attach(&callback);

    // reserve 4 bytes for transfer
    char cmd[4];

    // initialize the adc device
    cmd[0] = MAX1363_CONFIG_REG;
    cmd[1] = MAX1363_SETUP_REG;
    i2c.write(SLAVE_ADDRESS, cmd, 2);

    // holds raw adc values as we convert them
    unsigned int adc[2] = {0};
    float values[2] = {0};

    while (1) {
        wait(0.1);

        // clear buffer, only to detect invalid data
        cmd[0] = 0x00;
        cmd[1] = 0x00;
        cmd[2] = 0x00;
        cmd[3] = 0x00;

        // read 4 bytes from
        i2c.read(SLAVE_ADDRESS, cmd, 4);

        for (int i=0; i<4; i+=2) {
            // first 4 bits contain expected bits and channel id
            if ((cmd[i] & MAX1363_VALID_MASK) == MAX1363_VALID_MASK) {
                unsigned char ch = ((cmd[i] & MAX1363_CHANNEL_MASK) >> MAX1363_CHANNEL_SHIFT);
                adc[ch] = ((int)(cmd[i] & MAX1363_HIGH_DATA_MASK) << 8) | cmd[i+1];
                values[ch] = AdcToC(adc[ch]);
            } else {
                // handle invalid data
            }
        }
        x=values[1];
        if (x<SetTemp){
            Relay=0;
        }
        if (x>SetTemp+1){
            Relay=1;
        }
        // output temperature data
        printf("%0.2f\t %0.2f\t %0.2f\r\n", SetTemp, values[0], values[1]);

    }
}