eject CD/DVD tray using GPIO

gpeject.py

#!/usr/bin/python

# eject CD/DVD tray using GPIO to turn on motor until switch closes

import RPi.GPIO as GPIO
import signal
import sys
import time

GPIO.setmode(GPIO.BOARD)

TM = 18 # G24
OPSW = 22 # G25

MAX_SECONDS = 5

GPIO.setwarnings(False)
GPIO.setup([OPSW], GPIO.IN, pull_up_down=GPIO.PUD_UP)
GPIO.setup(TM, GPIO.OUT, initial=GPIO.LOW)

def motor(on):
	GPIO.output(TM, on)
	# TODO: allow driving each direction

	if on:
		# safety just in case switch doesn't fire
		def off():
			print "turning motor off after %s seconds" % (MAX_SECONDS,)
			motor(False)
			sys.exit(2)
		signal.signal(signal.SIGALRM, off)
		signal.alarm(MAX_SECONDS)

def handle(pin):
	value = GPIO.input(pin)
	if value == False:
		# OPSW low = fully open, turn off motor
		motor(False)
		print "ejected successfully"
		sys.exit(0)

GPIO.add_event_detect(OPSW, GPIO.BOTH, handle)

if GPIO.input(OPSW) == False:
	print "tray already open, not turning on motor"
	motor(False) # in fact, turn it off in case already on
	sys.exit(1)

motor(True)

time.sleep(10)