PC Fan Controller with LCD

Arduino to control a 12V PC fan and displays status on LCD. Bargraph and tachometer RPM speed. Basic operation is below.

• Supports any 4-bit or 8-bit LCD. Default is 16x2 characters
• Button inputs are software debounced
• Main loop uses a scheduler
• See code for list of configurable values

onoff_state = SYSTEM_OFF

Pressing on/off will:

• Command mosfet/relay to power to the fan
• Set the throttle to 20% (first boot) or last selected

onoff_state = SYSTEM_ON

Pressing on/off will:

• Command mosfet/relay to remove power from the fan
• Set the throttle to OFF Use the +/- buttons to go up and down in 10% chunks HOLDING (3 second count) on/off will set throttle to MAX_FAN_SPEED

When max speed is reached:

• Do not increase the pwm farther.
• A message is displayed to hold button to access fan speed beyond pwm = 255

When on/off is held for 3 seconds:

• Turn off PWM and ground the pin.
• This will set the fan to it's true max speed.

Current Bugs

• PWM library sets the Fan control PWM to 3.9khz instead of 25khz. Seems to work ok still.