Getting Intel Edison CPU core temperatures with code

[JKess]

Hi, I'm working on a program and I want to retrieve the cpu temperatures. Is it possible to get the temperatures of the separate cores with code? I tried using an ifstream to open the file, but I end up getting a segmentation fault. I'm using the Intel System Studio, and writing code in C++. I know where the files are that contain them, but I don't think it's allowing me to access the files and that's why it's giving me the segmentation fault. An example of the code I use to try to retrieve the temperatures is below. There are other blocks written the same way but accessing the different thermal_zones. Would be great if I could get this working. Thanks!

std::ifstream readFile; (This is in the header file)

readFile.open("/sys/devices/virtual/thermal/thermal_zone3/temp.txt");

if(readFile.is_open())

getline(readFile,core1Temp);

else{

core1Temp = "0";

}

temp = (atoi(core1Temp.c_str()))/1000;

convert << temp;

core1Temp = convert.str();

readFile.close();

[idata]

Hi thatboijo,

It should be possible to read the temperature for the Edison cores, and you're on the right track actually. However, I would suggest to use system calls. So for example from C, you could use the following:

system(cat /sys/class/thermal/thermal_zone1/temp)

If I'm not mistaken you'll get temperature values from thermal_zone1, thermal_zone3 and thermal_zone4. For zone0 and zone2 the cat command will throw a read error.

Regards,

-Pablo

[JKess]

Thanks! It works, but it's only printing out what the temp is. I've tried setting an int variable to it, and it just gets set to 0. I tried setting a string to it, and it was just a blank space. Can you not set a variable with that system call?

[idata]

Hi thatboijo,

It is possible to do it. However, as you already noticed, it is not possible to do it just by setting a variable and getting the value after reading it. This is because you're reading from outside your code (even if you're making a system call from your C program). One way to do it would be to make a system call to read the value and then to write the read value to a new/existing file (all of this using system calls), after that, using C file operations you'll just need to read the value from the file where you wrote it previously. I hope this all makes sense, please let us know if there's something you don't understand.Regards,-Pablo

[JKess]

Thanks Pablo, I finally got it. I used the open call to open the file I needed to read, the read call to read the contents of the file, and then the write call to write it to a new file in a location that I could retrieve it from.

int read1 = open("file_location", O_RDONLY); //FILE THAT I WANTED TO READ FROM.

int write1 = open("new_file", O_TRUNC | O_WRONLY | O_APPEND | O_CREAT, S_IXUSR); //NEW FILE THAT I WANTED TO CREATE

while((n = read(read1,buf,BUFSIZ) > 0))

write(write1,buf,read1);

close(read1);

close(read2);