A python utility to control a variable speed fan on a Raspberry Pi

This is specifically for the ICE Tower cooler from 52Pi as documented here. GPIO configuration for other PWM cooling fans may differ.

• Can be run as a normal user, e.g., via a user's crontab:
  • @reboot ~/.local/bin/rpi-fancontrol
• Applies a slope function to determine fan speed:
  • slope = (Speed_max / (TempUpperThreshold - TempLowerThreshold))
  • speed = (slope x (CurrentTemp - TempLowerThreshold))
• Applies a 2°C hysteresis to prevent rapid changes of fan speed
  • Temperature must move 2°C or more in either direction to adjust fan speed