GPIO strange behaviour

[poing]

I'm trying to do one of the MagPi articles using an GPIO input. I don't get it, when I execute the following code:

Code: Select all

import RPi.GPIO as GPIO
import time

GPIO.setmode(GPIO.BOARD)
GPIO.setup(11, GPIO.IN)

while True:
	myval=GPIO.input(11)
	print myval
	time.sleep(0.2)

The output is:

Code: Select all

False
False
False
False
True
True
True
True
True
True
True
True
True
True
True
True
True
True
True
True
False
False
False
False
False
False
False
False
False
False
False
False
False
False
False
False
False
True
True
True
True
True

Basically 17 times "True" followed by 17 times "False" and so on. Why does this happen?

[croston]

Have you got anything connected to that channel? If not, your input channel is 'floating'. This means that the input value is undefined electronically and therefore picks up electrical noise instead.

[Burngate]

http://www.raspberrypi.org/phpBB3/viewt ... 44&t=26802