Read Raspberry Pi 4B processing unit (CPU) real-time temperature

After Raspberry Pi release 4B, performance improved a lot, but the temperature is not high, so it is best to configure a small fan and heat sink is quite good

Two kinds of measures can be implemented

1.Shell command reads

Open a terminal

cd /sys/class/thermal/thermal_zone0

Check temperature

cat temp

Raspberry Pi return value

53069

The return value is divided by 1000 the current value of the CPU temperature. That the current temperature is 53 degrees Celsius. As shown below

2. write a program to read c language

Here, I basically copied https://blog.csdn.net/xukai871105/article/details/38349209 code,

Under revised increase of reading the print cycle 1s for a total of 100 times print program exits, so easy to see when the real-time refresh

Source Code

It is to look at the temperature / sys / class / thermal / thermal_zone0 / temp files

 1 #include<stdio.h>
 2 #include<stdlib.h>
 3 
 4 #include<sys/types.h>
 5 #include<sys/stat.h>
 6 #include<fcntl.h>
 7 
 8 #define TEMP_PATH "/sys/class/thermal/thermal_zone0/temp"
 9 #define MAX_SIZE 32
10 
11 int main(void)
12 {
13     int fd;
14     double temp = 0;
15     char buffer[MAX_SIZE];
16     int i;
17 
18     while(i < 100)
19     {
20         i+=1;
21         
22         //延时1s
23         sleep(1);
24         
25         //打开文件
26         fd = open(TEMP_PATH,O_RDONLY);
27         if(fd < 0)
28         {
29             fprintf(stderr,"Failed to open thermal_zone0/temp\n");
30             return - 1;
31         }
32 
33         //Reading the file 
34 is          IF (Read (FD, Buffer, MAX_SIZE) < 0 )
 35          {
 36              fprintf (stderr, " the Failed to Read TEMP \ n- " );
 37 [              return - . 1 ;
 38 is          }
 39      
40          // calculated temperature value 
41 is          TEMP atoi = (Buffer) / 1000.0 ;
 42 is          
43 is          // printout temperature 
44 is          the printf ( " the Temp:. 4F% \ n- " , TEMP);
 45  
46 is          // close file 
47          Close (FD);
48     }
49 }

Write code

Create a program and open the file ReadTemp.c write code

Compile and run results

gcc -o ReadTemp ReadTemp.c there are three compiler warning, you can not ignore it, you can generate executable file to run the program ReadTemp input ./ReadTemp

(I installed fans and heat sinks and housing, probably average about 53 degrees Celsius)

hardware information

Information cpu and memory information

Read Raspberry Pi 4B processor (CPU) of the real-time temperature