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Raspberry 4/4B Fan Hat Manual

1. Use of script
First, you need to install his GPIO access library on the Raspberry Pi by accessing the system with SSH or opening a terminal:

cd /tmp

wget sudo dpkg -i wiringpi-latest.deb

Waiting to download and install WireingPi:

 sudo dpkg -i wiringpi-latest.deb

Check out Gpio:

 gpio -v

2. Create a text document
Then create a text document in your home directory and copy the contents of

  1.  #!/bin/bash
  2. #Define GPIO pin 18 as PWM
  3. gpio -g mode 18 pwm
  4. num=true
  5. while [ $num ];
  6. do
  7. # Print CPU temp
  8. temp=$(cat /sys/class/thermal/thermal_zone0/temp)
  9. temp=$(($temp/1000))
  10. clear
  11. printf "Temperature: $tempºC\nTurning on fan."
  12. # Variable temperature control
  13. if [ $temp -gt 40 ] && [ $temp -lt 69 ];
  14. then
  15. vartemp=$(echo $[ temp * 13 ])
  16. gpio -g pwm 18 $vartemp
  17. # Maximum fan RPM
  18. elif [ $temp -ge 69 ];
  19. then
  20. gpio -g pwm 18 1024
  21. # Switch off the fan
  22. else
  23. gpio -g pwm 18 0
  24. clear
  25. printf "Temperature: $tempºC\nFan off."
  26. sleep 60
  27. fi
  28. #Pause 1 second
  29. sleep 1
  30. done
  31. exit 0
 cd ~

Paste the script and save it with CTRL+X. When we exit the editor, we'll give the script execution permissions with:

 sudo chmod +x

Now the script is ready to be used. But we'll need run it manually every time the computer is started. To solve this we'll use a Linux daemon called Cron:

 crontab -e

Paste the next line at the end of the file where there is no #:

 @reboot /bin/bash /home/pi/ > /dev/null 2>&1

Save it with CTRL+X and exit.
Now the script is scheduled. To execute it we need to restart and it'll start running in the background.

 sudo reboot


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