Raspberry Pi: CPU Temperature Monitor

Installing Necessary Software

1. Open up a terminal shell, this can be done by clicking on this icon on the right:
   • Alternatively, a new shell can be opened by pressing crtl + alt + t.
2. Next, ensure that matplotlib is installed by entering the command sudo apt-get install python3-matplotlib.
3. If it installs or confirms that matplotlib is installed, proceed to the next step.

Creating the Python Script

1. Open a new blank Python file by Menu > Programming > Mu.
   • The menu is the RaspberryPi logo in the top left.
2. After launching Mu, select Python 3 and click OK.
3. In Mu, under the first commend enter in these lines of code:
   • from gpiozero import CPUTemperature
   • cpu = CPUTemperature()
4. Save the program as temp then click Run.
   • A run time menu will appear with a »> as a prompt.
   • Type in cpu.temperature to this prompt to get a temperature readout of the CPU in Celcius.
5. Now, let’s make the script more robust by having a log of the temperatures. To do this, copy in the following lines:

from gpiozero import CPUTemperature

from time import sleep, strftime, time

from gpiozero import CPUTemperature

cpu = CPUTemperature()

with open(“cpu_temp.csv”, “a”) as log:

while True:

temp = cpu.temperature

log.write(‘{0},{1}\n’.format(strftime(‘%Y-%m-%d %H:%M:%S’), str(temp)))

1. Running this code will keep a log in the form of a CSV in the designated folder. This folder can be found in /home/pi and will be called cpu_temp.csv.
2. Try running the code and finding the file.
3. Now that a log is kept, visualization in the form of a real time graph can be scripted.
4. Copy over the following code to the script, save and run.

from gpiozero import CPUTemperature

from time import sleep, strftime, time

import matplotlib.pyplot as plt

cpu = CPUTemperature()

def write_temp(temp):

with open(‘cpu_temp.csv’, ‘a’) as log:

log.write(‘{0},{1}\n’.format(strftime(‘%Y-%m-%d %H:%M:%S’), str(temp)))

def graph(temp):

y.append(temp) x.append(time()) plt.clf() plt.scatter(x,y) plt.plot(x,y) plt.draw()

while True:

temp = cpu.temperature write_temp(temp) graph(temp) plt.pause(1)

1. Save and run this script to get a graph of the current cpu temperature.

Automating the Script

1. This Python script can be made to run automatically on boot.
2. Open a new terminal and enter in crontab -e to open crontab. If prompted, choose nano from the options given.
3. Scroll to the bottom of the opened file and enter in this line in a new line: @reboot python3 /home/pi/temp.py
4. Now, reboot the Raspberry Pi by entering the command sudo reboot.
5. Once the pi has reboot and run for a bit, enter the command cat cpu_temp.csv.
6. This will display a log of the recent CPU temperature.

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