Copying functionality for Fan Shim by PIMORONI using a simple Adafruit fan, push button, fan control circuit and custom software. Raspberry Pi GPIO pin 19, header pin 35 (see PWM HAT pins), used to connect the control push-button and one PWM HAT channel to provide control and power to the fan (16-channel PWM HAT, address 0, channel 0. See related: Design Considerations, and The Process, 9 - 15 Dec '19 , 16 - 22 Dec '19 , 17 - 23 Feb '20 and 24 Feb - 1 Mar '20).


  • Push Button
    • Manual/Auto Mode (Press & hold)
    • Manual Mode On/Off (Push on/off)
  • Monitor CPU Temperature
  • Monitor CPU Frequency
  • Control fan based on:
    • Mode set by push-button
    • CPU Temperature and parameters set
    • CPU Frequency and parameter option
  • Display Status on Unicorn
    • Relative Temperature, 5-step ladder
    • Fan on/off
    • Manual/Auto mode
    • Frequency normal/throttled