I have a simple code that read the input from pin 17 (BCM).

import RPi.GPIO as GPIO
from time import sleep

GPIO.setup(17, GPIO.IN)

  while True:
except KeyboardInterrupt:

The case is when I don't enter a power, the value is 0 and when the power is entered, the value is 1.

But when I don't enter power at all, the value suddenly changes from 0 to 1, and 1 becomes 0 automatically repeated.


If the value floats between low and high that is because the GPIO is floating. Floating means the GPIO has not been set high (by connecting it to 3V3) or low (by connecting it to ground).

That is why a pull-up or pull-down is often connected to a GPIO - so that it is in a known fixed state when not overridden by a more powerful voltage.

E.g. see https://embeddedartistry.com/blog/2018/6/4/demystifying-microcontroller-gpio-settings

| improve this answer | |
  • I don't know about this, I'm newbie for this thing. Thanks for your answer – willydwi77 Jul 20 '19 at 14:37
  • if it worked the accept his answer – Allaw Hussein Aug 19 '19 at 18:11

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