SafeShutdown.py Script for Retroflag Nespi4 on Debian Bookworm using gpiod instead of the legacy RPi.GPIO

SafeShutdown.py

## This script was written by Claude Code when I was trying to set up Safe Shutdown on Bookworm
## Claude told me not to do this but I told it "Make It So!"
## The script worked on the first run, but I don't make any guarantees about it
## Hopefully if you're reading this it will help you too. 
## Please link this gist to any threads out there that need it.

import gpiod
import os
import time
import signal
import sys
from multiprocessing import Process

# GPIO pin definitions
POWER_PIN = 3    # pin 5
LED_PIN = 14     # TXD
RESET_PIN = 2    # pin 13
POWEREN_PIN = 4  # pin 5

# Open GPIO chip
chip = gpiod.Chip('gpiochip4')  # RPi4 uses gpiochip4

# Define lines
power_line = chip.get_line(POWER_PIN)
reset_line = chip.get_line(RESET_PIN)
led_line = chip.get_line(LED_PIN)
poweren_line = chip.get_line(POWEREN_PIN)

def init():
    """Initialize GPIO pins"""
    try:
        # Configure power and reset as inputs with pull-up
        power_line.request(
            consumer="power",
            type=gpiod.LINE_REQ_DIR_IN,
            flags=gpiod.LINE_REQ_FLAG_BIAS_PULL_UP
        )
        reset_line.request(
            consumer="reset",
            type=gpiod.LINE_REQ_DIR_IN,
            flags=gpiod.LINE_REQ_FLAG_BIAS_PULL_UP
        )

        # Configure LED and power enable as outputs
        led_line.request(
            consumer="led",
            type=gpiod.LINE_REQ_DIR_OUT,
            default_val=1  # HIGH
        )
        poweren_line.request(
            consumer="poweren",
            type=gpiod.LINE_REQ_DIR_OUT,
            default_val=1  # HIGH
        )
    except Exception as e:
        print(f"GPIO initialization error: {e}")
        sys.exit(1)

def listen():
    """Listen for button presses"""
    print("SafeShutdown listening for power button...")
    power_pressed = False
    reset_pressed = False

    try:
        while True:
            # Read power button
            power_state = power_line.get_value()
            if power_state == 0 and not power_pressed:  # Button pressed (LOW)
                power_pressed = True
                print("Power button pressed, initiating shutdown...")
                os.system("sudo shutdown -h now")

            elif power_state == 1:  # Button released (HIGH)
                power_pressed = False

            # Read reset button
            reset_state = reset_line.get_value()
            if reset_state == 0 and not reset_pressed:  # Button pressed (LOW)
                reset_pressed = True
                print("Reset button pressed, initiating reboot...")
                os.system("sudo shutdown -r now")

            elif reset_state == 1:  # Button released (HIGH)
                reset_pressed = False

            time.sleep(0.1)  # Poll every 100ms

    except KeyboardInterrupt:
        print("\nShutdown listener stopped")
    finally:
        # Release GPIO
        power_line.release()
        reset_line.release()
        led_line.release()
        poweren_line.release()

def signal_handler(sig, frame):
    """Handle termination signals gracefully"""
    print("Received signal, cleaning up...")
    try:
        power_line.release()
        reset_line.release()
        led_line.release()
        poweren_line.release()
    except:
        pass
    sys.exit(0)

if __name__ == "__main__":
    signal.signal(signal.SIGTERM, signal_handler)
    signal.signal(signal.SIGINT, signal_handler)

    init()
    listen()