Pi Pico Motherboard Controller

This project turns a Raspberry Pi Pico into a custom PC power management controller, designed to interface a modern case with a proprietary motherboard and a 12VO power supply.

This controller solves several hardware compatibility issues:

• It generates the missing PWR_OK ("Power Good") signal required by the motherboard to boot safely.
• It intelligently controls the case fans via a 5V relay, adding a five-minute cooldown period after the PC shuts down.
• It reads the case's power and reset buttons and uses a second relay to operate the motherboard's power switch.
• It knows if the PC is on or off by directly sensing the 5V power from a motherboard USB port.

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🔌 Final Pinout Guide

This pinout matches your selected project version.

⚡ Power & Ground

• VBUS (Pin 40): Power Input
  • Connects to: The +5V wire from your external power supply.
• GND (e.g., Pin 38): Common Ground
  • Connects to: The Ground from your external PSU, shared with all other components.

📥 Inputs (Sensing)

• GP14 (Pin 19): Case Power Button
  • Connects to: The case's physical power button.
• GP15 (Pin 20): Case Reset Button
  • Connects to: The case's physical reset button.
• GP22 (Pin 29): PC Power State Sensor
  • Connects to: The +5V wire from a motherboard USB port.

📤 Outputs (Control)

• GP12 (Pin 16): Motherboard Power Control
  • Connects to: The Low-Voltage (LV) input on your logic level converter for the power button relay.
• GP16 (Pin 21): Case LED Control
  • Connects to: The positive (+) lead of the case's front panel LED.
• GP17 (Pin 22): Power OK Signal
  • Connects to: The Low-Voltage (LV) input on your logic level converter for the PWR_OK signal.
• GP18 (Pin 24): Fan Relay Control
  • Connects to: The Low-Voltage (LV) input on your logic level converter for the fan relay.

Other

• Fan Relay:

  • Connects to: NC (Normally Closed) terminal on your fan relay.

• MOBO PWR Relay:

  • Connects to: NO (Normally Open) terminal on your power button relay.