How to read from a TC74 Temperature sensor on the Raspberry Pi.
float read_temp(int address, char bus) {
unsigned int temp = 0;
unsigned char msb, lsb;
int fd; // File descriptor
char *fileName;
//int address = 0x49; // Address of TP102
unsigned char buf[10]; // Buffer for data being read/ written on the i2c bus
if (bus == 1)
fileName = "/dev/i2c-1"; // Name of the port we will be using
else
fileName = "/dev/i2c-0";
if ((fd = open(fileName, O_RDWR)) < 0) { // Open port for reading and writing
printf("Failed to open i2c port\n");
exit(1);
}
if (ioctl(fd, I2C_SLAVE, address) < 0) { // Set the port options and set the address of the device we wish to speak to
printf("Unable to get bus access to talk to slave\n");
exit(1);
}
buf[0] = 0; // This is the register we wish to read from
if ((write(fd, buf, 1)) != 1) { // Send register to read from
printf("Error writing to i2c slave\n");
exit(1);
}
if (read(fd, buf, 1) != 1) { // Read back data into buf[]
printf("Unable to read from slave\n");
exit(1);
}
else {
temp = buf[0];
//printf("The temperature is: %f C\n",temp);
return temp;
}
}
}