How to add timed delay in Python for hardware control

Question

I have managed to construct some python code on a Raspberry PI to control a garage door. However I don't know how to add a timed delay so that the control is limited to the correct movement time.

Any help would be appreciated.

My working code is below.

    import RPi.GPIO as GPIO          
    from time import sleep

    in1 = 24
    in2 = 23
    en = 25
    temp1=1

   GPIO.setmode(GPIO.BCM)
   GPIO.setup(in1,GPIO.OUT)
   GPIO.setup(in2,GPIO.OUT)
   GPIO.setup(en,GPIO.OUT)
   GPIO.output(in1,GPIO.LOW)
   GPIO.output(in2,GPIO.LOW)
   p=GPIO.PWM(en,1000)
   p.start(25)
   print("\n")
   print("The default speed & direction of motor is LOW & Forward.....")
   print("r-run s-stop f-forward b-backward l-low m-medium h-high e-exit")
   print("\n")    

   while(1):
   x = input()
   if x=='r':
   print("run")
   if(temp1==1):
   GPIO.output(in1,GPIO.HIGH)
   GPIO.output(in2,GPIO.LOW)
   print("forward")
   x='z'
   else:
   GPIO.output(in1,GPIO.LOW)
   GPIO.output(in2,GPIO.HIGH)
   print("backward")
   x='z'


   elif x=='s':
   print("stop")
   GPIO.output(in1,GPIO.LOW)
   GPIO.output(in2,GPIO.LOW)
   x='z'

   elif x=='f':
   print("forward")
   GPIO.output(in1,GPIO.HIGH)
   GPIO.output(in2,GPIO.LOW)
   temp1=1
   x='z'

   elif x=='b':
   print("backward")
   GPIO.output(in1,GPIO.LOW)
   GPIO.output(in2,GPIO.HIGH)
   temp1=0
   x='z'

   elif x=='l':
   print("low")
   p.ChangeDutyCycle(25)
   x='z'

   elif x=='m':
   print("medium")
   p.ChangeDutyCycle(50)
   x='z'

   elif x=='h':
   print("high")
   p.ChangeDutyCycle(75)
   x='z'


    elif x=='e':
    GPIO.cleanup()
    break

    else:
    print("<<<  wrong data  >>>")
    print("please enter the defined data to continue.....")

score 1 · Answer 1 · edited Oct 23 '18 at 02:23

1

Can't help with PI code but would like to add a little warning. If you rely on time to switch off the motor then any cars, kids, bikes etc would be crushed by the closing door. Can you interface a current sensor to the Pie so that it stops when the motor current exceeds a certain amount? Have a look at These

Mike.

edited Oct 23 '18 at 02:23

Preet Sangha

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answered Oct 23 '18 at 02:15

PommieMike

11
5

Yes thank you, I am aware and plan on adding that feature in the future. – Cody Dieckow Oct 23 '18 at 02:35
Good call on that sensor! – Cody Dieckow Oct 23 '18 at 02:35

score 0 · Answer 2 · answered Oct 23 '18 at 02:22

This question and answer How can I make a time delay in Python? shows how to add a timed delay in your code.

import time
# delay for 10 seconds
time.sleep(10)

However this is not the best solution. Better to use the solutions here : https://raspberrypi.stackexchange.com/questions/69640/add-delay-between-two-gpio-output and I'd also suggest you use pins to capture information such as open or closed from the door perhaps using sensors switches (of which there are various types).

How to add timed delay in Python for hardware control

2 Answers2