9: Monitor the temperature of Raspberry Pi on ThingSpeak Cloud

ThingSpeak is an IoT analytics platform service that can process, visualize and live stream data in the cloud. In this tutorial, you are going to write a program to implement the following tasks simultaneously. 

(1) Send CPU temperature data of Raspberry Pi 4B to ThingSpeak Cloud. 

(2) Turn on cooling fan if the CPU temperature of Raspberry Pi 4B is higher than 46 degree Celcius. 

https://thingspeak.com/pages/commercial_learn_more

Step 1: Register account in ThingSpeak via https://thingspeak.com/login

Step 2: Create a new project and write down 'Channel ID'

Step 3: Write down the API keys that will be used in your python code in step 6

Step 4: Build a simple electronic circuit

Step 5: Install ThingSpeak in Raspberry Pi

Command: sudo pip install thingspeak

Here we do not need httplib and urllib because ThingSpeak has integrated them 

Step 6: Store the following code as app.py

import thingspeak

import time

from time import sleep

import os

import signal

import sys

import RPi.GPIO as GPIO

channel_id=********    # Your channel ID 

write_key = '********'  # Your API Key 

def thermometer(channel):        

        try:

            #Calculate CPU temperature of Raspberry Pi in Degrees C

            temp = int(open('/sys/class/thermal/thermal_zone0/temp').read()) / 1e3 

            print(temp)

            response = channel.update({'field1': temp})

            read=channel.get({})

        except:

            print("connection failed")

            

pin = 16 # GPIO pin

max_temp = 46 # The threshold temperature in Celsius to turn on electric fan

def setup():

    GPIO.setmode(GPIO.BCM)

    GPIO.setup(pin, GPIO.OUT)

    GPIO.setwarnings(False)

    return()

def getCPUtemperature():

    temp = int(open('/sys/class/thermal/thermal_zone0/temp').read()) / 1e3 

    print(temp) 

    return temp

def fanON():

    setPin(True)

    return()

def fanOFF():

    setPin(False)

    return()

def getTEMP():

    CPU_temp = float(getCPUtemperature())

    if CPU_temp>max_temp:

        fanON()

    else:

        fanOFF()

    return()

def setPin(mode): 

    GPIO.output(pin, mode)

    return()

        

if __name__ == "__main__":

    channel=thingspeak.Channel(id=channel_id,api_key=write_key)

    try:

        setup() 

        while True:

            thermometer(channel)     # communicate to ThingSpeak

            getTEMP()                           # communicate to Raspberry Pi  

        sleep(10)

    except KeyboardInterrupt: 

        GPIO.cleanup() 

#The above code is modified from open-source platform

Step 7: Set the channel as private or public. Then observe the temperature data

When temperature exceed 46 Degree Celsius, the electric fan is turned on and then the CPU starts to cool down. Of course you can download the data from ThingSpeak Cloud