how to change variable value automatically in while loop?

Question

I'm trying to control led lights based on its previous state using python code on my raspberry pi. Any suggestion how can I do it?

I have tried using checking gpio state using gpio.input() function, and changing variable value

GPIO.setmode(GPIO.BOARD)
GPIO.setwarnings(False)
GPIO.setup(35,GPIO.OUT)
GPIO.output(35,GPIO.HIGH)

f = '1'

while True:
    time.sleep(3)
    print "before"
    print f
    if f == '1':
        GPIO.output(35,GPIO.HIGH)
        f = '0'

    if f == '0':
        GPIO.output(35,GPIO.LOW)
        f = '1'
    print "after"
    print f
time.sleep(3)

I expect to turn off light if it is in on condition and vice-versa

What is currently happenning when you run this?

OneCricketeer
– OneCricketeer

2019-04-06 19:11:41 +00:00
Commented Apr 6, 2019 at 19:11 — OneCricketeer
– OneCricketeer, Commented Apr 6, 2019 at 19:11

Pavel Smirnov · Accepted Answer · 2019-04-06 21:56:59Z

1

Your code is changing f from 1 to 0 and then immediately changing it back again, so your code is working, but it switches the light off so quickly again you don't see it.

Change this line

if f == '0':

to

elif f == '0':

edited Apr 6, 2019 at 21:56

Pavel Smirnov

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answered Apr 6, 2019 at 19:18

BoarGules

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