Run a part of code every 5 min independently of the other commands

Question

I want to open, stay open for 6 seconds and close one relay every 5 minutes while the rest code running normally.

For example:

GPIO.output(18, 1)
sleep(6)
GPIO.output(18, 0)
sleep(300)

But without the rest program stacks in this delay. My Python code is:

import RPi.GPIO as GPIO
from time import sleep

GPIO.setmode(GPIO.BOARD)
GPIO.setup(13, GPIO.IN, GPIO.PUD_UP)
GPIO.setup(7,GPIO.OUT)
GPIO.setup(37, GPIO.OUT)
Hologram = '/home/pi/Hologram/Hologram.mp4'

from subprocess import Popen

firstTimeOpen=0

while True:

        doorIsOpen = GPIO.input(13)

        if doorIsOpen==0 and firstTimeOpen == 0:
                        firstTimeOpen=1
                        GPIO.output(7, 0)
                        GPIO.output(37, 0)
                        sleep(0.5)

        if doorIsOpen==1 and firstTimeOpen == 1:
                GPIO.output(7, 1)
                GPIO.output(37, 1)
                omxp = Popen(['omxplayer' ,Hologram])
                sleep(87)
                GPIO.output(7, 0)
                GPIO.output(37, 0)
                firstTimeOpen=0
                sleep(0.5)

Answer 1

Threads offer a convenient way to do this. I normally create a threading.Thread subclass, whose run method is the code to be run in a separate thread. So you would want something like:

class BackgroundRunner(threading.thread):
    def run(self):
        while True:
            GPIO.output(18, 1)
            sleep(6)
            GPIO.output(18, 0)
            sleep(300)

Then, before you start running your main code, use

bg_runner = BackgroundRunner()
bg_runner.start()

Answer 2

Apart from the suggested threading methods, you can also use an interrupt using the python signal module. Interrupts are cheaper than threads, which may be more appropriate on your chosen platform.

You can find more examples here: https://docs.python.org/2/library/signal.html

As an example:

import signal, os

def handler(signum, frame):
    print 'Signal handler called with signal', signum
    handler.counter += 1

    if not handler.counter % (300 / 6):
        GPIO.output(18, 0)
    else:
        GPIO.output(18, 1)

handler.counter = 0

signal.signal(signal.ITIMER_REAL, handler)
signal.setitimer(signal.ITIMER_REAL, 0, 6)