I am making a graph on the temperature using a NTC resistor and also by reading the CPU temperature, however I'd also like to read the GPU temperature.

I read this answer explaining briefly how to read the CPU temperature from C. How would I read the GPU temperature aswell?

If there isn't any better solution I persume one can use the output of vcgencmd

/opt/vc/bin/vcgencmd measure_temp

but is there not a cleaner way?

2 Answers 2


/opt/vc/bin/vcgencmd measure_temp

This returns the same thing as reading /sys/class/thermal, i.e., the core temp. Reading the /sys file is preferable programmatically because it is just a sequence of open/read system calls, instead of a fork/execute plus a bunch of open/read/write with pipes.

How would I read the GPU temperature aswell?

The BCM2835/6 used on the Pi/Pi 2 is a SoC, i.e., one chip, with one temperature. The GPU temp == the CPU temp.

  • Oh that makes sense actually. I guess (this)[ bhavyanshu.me/tutorials/… script only checks the average so that's why I thought they differ.
    – Linus
    Oct 24, 2015 at 18:23
  • @Linus your link is broken: here it is not broken for future readers.
    – randers
    Oct 24, 2015 at 20:05

Here's a function called get_temp that returns the temperature in Farenheit or Celcius.

Make a file called temp.c and compile it with gcc temp.c -o temp

Here is temp.c:

#include <stdio.h>
#include <string.h>
#include <stdbool.h>
double get_temp(bool use_farenheit);
int main(int argc,char *argv[])
  // Display the temperature to the user.
  printf("Temperature = %3.3f'C or %3.3f'F\n",get_temp(false),get_temp(true));
  return 0;
// Returns the temp in Farenheit or Celcius. Returns -1000 if something went wrong.
double get_temp(bool use_farenheit)
  const int BUFFER_SIZE = 100;
  char data[BUFFER_SIZE];
  FILE *finput;
  size_t bytes_read;
  double temp = -1000;
  finput = fopen("/sys/class/thermal/thermal_zone0/temp","r");
  if (finput != NULL) {
    temp = atoi(data);
    temp /= 1000;
    if (use_farenheit) {
      temp = temp * 9 / 5 + 32;
  return temp;

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.