Blink LED on Press, 3 Second Button Hold Delay

listen-for-shutdown.py

@@ -1,12 +1,58 @@
 #!/usr/bin/env python
-
-
 import RPi.GPIO as GPIO
 import subprocess
+import time
+
+print('Raspberry PI GPIO Button & LED Shutdown Script')
+
+# Pin Definitions
+PIN_LED    = 4 # GPIO4 / Pin #7
+PIN_BUTTON = 3 # GPIO3 / Pin #5
+
+try:
+    # Button Press Logic
+    def button_interupt(channel):
+        time_start = time.time()
+        time_button = 0
+        led_state = GPIO.LOW
+        time_pressed_max = 3 # seconds
+
+        # Loop while button is pressed, and not passed max time
+        while GPIO.input(channel) == GPIO.LOW and time_button <= time_pressed_max: # wait for the button up
+            # DEBUGGING OUTPUT
+            print("Button:", time_button, led_state)
+
+            # Blink LED
+            GPIO.output(PIN_LED, led_state)  # blink LED
+            led_state = not led_state
+            time.sleep(0.1) #loop time and led blink interation rate.
+
+            # How long was the button down?
+            time_button = time.time() - time_start    
+
+        # Set LED back to High, just in case was low.
+        GPIO.output(PIN_LED, GPIO.HIGH)  # blink LED
+
+        # Determine Button Time
+        if time_button >= time_pressed_max:
+            print("Power Button Pressed & Held:", time_button)
+            subprocess.call(['shutdown', '-h', 'now'], shell=False) # Power Off
+
+    # Ignore Warrnings or not
+    GPIO.setwarnings(False)    # Ignore warning for now
+
+    # Setting GPIO layout
+    GPIO.setmode(GPIO.BCM)   # GPIO.setmode(gpio.BOARD) | Use boards header pin order or lableing GPIO##. https://iot4beginners.com/difference-between-bcm-and-board-pin-numbering-in-raspberry-pi/
 
+    # # Set pin as input pin pulled down to GND
+    GPIO.setup(PIN_LED, GPIO.OUT, initial=GPIO.HIGH)           # LED ON
+    GPIO.setup(PIN_BUTTON, GPIO.IN, pull_up_down=GPIO.PUD_UP)  # Button
 
-GPIO.setmode(GPIO.BCM)
-GPIO.setup(3, GPIO.IN, pull_up_down=GPIO.PUD_UP)
-GPIO.wait_for_edge(3, GPIO.FALLING)
+    # # Button Press Event
+    GPIO.add_event_detect(PIN_BUTTON, GPIO.FALLING, callback=button_interupt, bouncetime=100)
 
-subprocess.call(['shutdown', '-h', 'now'], shell=False)
+    # Sleep Forever, to keep script alive, button_interupt handles everything.
+    while True:
+        time.sleep(86400)
+except:
+    GPIO.cleanup()

listen-for-shutdown.service

@@ -0,0 +1,11 @@
+[Unit]
+Description=Listen for shutdown service at GPIO3
+After=syslog.target network.target
+
+[Service]
+Type=simple
+ExecStart=/usr/bin/python3 /usr/local/bin/listen-for-shutdown.py
+PIDFile=/run/listen-for-shutdown.pid
+
+[Install]
+WantedBy=multi-user.target

script/install.systemd

@@ -0,0 +1,21 @@
+#! /bin/sh
+
+set -e
+
+cd "$(dirname "$0")/.."
+
+echo "=> Installing shutdown listener...\n"
+sudo cp listen-for-shutdown.py /usr/local/bin/
+sudo chmod +x /usr/local/bin/listen-for-shutdown.py
+
+echo "=> Installing shutdown listener systemd service...\n"
+sudo cp listen-for-shutdown.service /etc/systemd/system/
+sudo chmod +x /etc/systemd/system/listen-for-shutdown.service
+
+echo "=> Starting shutdown listener...\n"
+sudo systemctl daemon-reload
+sudo systemctl enable listen-for-shutdown.service
+sudo systemctl start listen-for-shutdown.service
+sudo systemctl status listen-for-shutdown.service
+
+echo "Shutdown listener installed.\n"

script/uninstall.systemd

@@ -0,0 +1,18 @@
+#! /bin/sh
+
+set -e
+
+cd "$(dirname "$0")/.."
+
+echo "=> Stopping shutdown listener...\n"
+sudo systemctl stop listen-for-shutdown.service
+
+echo "=> Removing shutdown listener...\n"
+sudo systemctl disable listen-for-shutdown.service
+sudo systemctl status listen-for-shutdown.service
+sudo rm -f /etc/systemd/system/listen-for-shutdown.service
+sudo rm -f /usr/local/bin/listen-for-shutdown.py 
+
+echo "=> Reloading systemd services...\n"
+sudo systemctl daemon-reload
+echo "Shutdown listener uninstalled.\n"