Power Management Script for Raspberry PI UPS Shield Geekworm x1200

upsmon.py

#!/usr/bin/env python3
import os
import dbus
import gpiod
import time
import logging
from argparse import ArgumentParser, Namespace
from datetime import datetime

PLD_PIN = 6
GPIO_CHIP = "gpiochip0"


def parse_args() -> Namespace:
    parser = ArgumentParser(description="Monitor UPS power status.")
    parser.add_argument(
        "--enable-shutdown",
        action="store_true",
        help="Enable shutdown on power outage.",
    )
    parser.add_argument(
        "--wait-time",
        type=int,
        default=300,
        help="Wait time (in seconds) before shutting down on power loss.",
    )
    return parser.parse_args()


def system_shutdown() -> None:
    bus = dbus.SystemBus()
    systemd = bus.get_object("org.freedesktop.systemd1", "/org/freedesktop/systemd1")
    manager = dbus.Interface(systemd, "org.freedesktop.systemd1.Manager")
    manager.Halt()


def ensure_root() -> None:
    if os.geteuid() != 0:
        logging.fatal("Error: This script must be run as root.")
        exit(1)


def monitor_power(enable_shutdown: bool, waittime: int) -> None:
    chip = gpiod.Chip(GPIO_CHIP)
    pld_line = chip.get_line(PLD_PIN)
    pld_line.request(consumer="PLD", type=gpiod.LINE_REQ_DIR_IN)

    last_state = None
    power_loss_time = None

    try:
        while True:
            pld_state = pld_line.get_value()
            if pld_state != last_state:
                last_state = pld_state
                if pld_state == 1:
                    logging.info("AC Power OK, Power Adapter OK")
                    power_loss_time = None
                else:
                    logging.info("AC Power Loss OR Power Adapter Failure")
                    power_loss_time = datetime.now()

            if power_loss_time:
                elapsed_time = datetime.now() - power_loss_time
                if elapsed_time.total_seconds() > waittime:
                    if enable_shutdown:
                        logging.critical(
                            f"Power outage lasted for {elapsed_time.total_seconds()} seconds. Shutting down now."
                        )
                        system_shutdown()
                        break
                    else:
                        logging.info(
                            f"Power outage lasted for {elapsed_time.total_seconds()} seconds, but shutdown is disabled."
                        )

            time.sleep(5)

    finally:
        pld_line.release()


def main():
    logging.basicConfig(level=logging.INFO, format="[%(levelname)s] %(message)s")
    ensure_root()
    args = parse_args()
    monitor_power(enable_shutdown=args.enable_shutdown, waittime=args.wait_time)


if __name__ == "__main__":
    main()

upsmon.service

[Unit]
Description=UPS Monitor Service
After=network.target

[Service]
ExecStart=/usr/local/sbin/upsmon --enable-shutdown
Restart=on-failure
User=root
Group=root

[Install]
WantedBy=multi-user.target