CODEWITHSUNDEEP
python
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butbut

Reputation: 47

Python if loop time.sleep only execute once

Below code is for a PIR sensor written in Python.

What it should do

When the sensor was activate the first time, it should wait for 10 second once and then keep printing "Intruder detected" until the sensor was = 0.

what is actually do

Rather than waiting 10s once, the code below wait ever 10s when the pir sensor was tigger.

Why is that?

import RPi.GPIO as GPIO
import time
GPIO.setwarnings(False)
GPIO.setmode(GPIO.BOARD)
GPIO.setup(11, GPIO.IN)         #Read output from PIR motion sensor
GPIO.setup(3, GPIO.OUT)         #LED output pin
while True:
       i=GPIO.input(11)
       if i==0:                 #When output from motion sensor is LOW
             print "No intruders",i
             GPIO.output(3, 0)  #Turn OFF LED
             time.sleep(0.1)
       elif i==1:               #When output from motion sensor is HIGH
             time.sleep(10)     #This should be only run once when the pir sensor is trigger
             print "Intruder detected",i
             GPIO.output(3, 1)  #Turn ON LED
             time.sleep(0.1)

Upvotes: 0

Views: 363

Answers (1)

Patrick Artner
Patrick Artner

Reputation: 51683

Simply remember if it was triggererd:

import RPi.GPIO as GPIO
import time
GPIO.setwarnings(False)
GPIO.setmode(GPIO.BOARD)
GPIO.setup(11, GPIO.IN)         # Read output from PIR motion sensor
GPIO.setup(3, GPIO.OUT)         # LED output pin
wasTriggered = False            # not yet triggered
while True:
       i=GPIO.input(11)
       if i == 0:                          # When output from motion sensor is LOW
             print "No intruders",i
             wasTriggered = False          # reset trigger if True else does nothing
             GPIO.output(3, 0)             # Turn OFF LED
             time.sleep(0.1)
       elif i == 1:                        # When output from motion sensor is HIGH
             if wasTriggered == False:     # already triggered ?
                 time.sleep(10)            # only run once when the pir sensor is trigger
                 print "Intruder detected",i
                 GPIO.output(3, 1)         # Turn ON LED
                 wasTriggered = True       # set was triggered 
             time.sleep(0.1)

This is creating a "memory" - it will only reset once the Sensor reports one 0 on pin 11. You might want to switch the "Led goes red + Output text" and the sleep around to make it more "snappy" - meaning it will react immediately to the sensor change and then pause for 10s instead of pausing for 10s and then switch the light & print text which would disconnect the "Act"->"React" sequence.

Upvotes: 1

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