树莓派GPIO输入不稳定

Question

I have a strange problem with raspberry (3B) ang GPIO as Input. I'm actually just experimenting and trying to get a pushbutton press without side effects.

setup

Hardware

• PIN 16 (GPIO 26) as IN
• PIN 6 as GND
• 2 open Jumper wires on the pins for better debugging. Later there will be pushbutton behind

Software

• Raspbian 9.4 stretch
• Kernel 4.9.80-v7+ (newest over normal apt-get)
• RPi.GPIO version 0.63

code

#!/usr/bin/python
import RPi.GPIO as GPIO
from time import sleep

red_channel = 23

GPIO.setmode(GPIO.BCM)
GPIO.setup(red_channel, GPIO.IN, pull_up_down=GPIO.PUD_UP) # pin is up to 3.3V

try:
    while True:
        state = GPIO.input(red_channel)
        if state == 0: # when pin pulled down
            print 'red pressed', state
        sleep(0.3)
except KeyboardInterrupt:
    GPIO.cleanup()

Problem

When I run the code and only come with my hand in the near of the jumper wires or even move them, button pressure will be detected. And at this point I don't get why! Did I get something wrong?

Solutions already tried

• new wires
• other ports
• other raspberry (same version)!
• OS new installed and GPIO Libs fresh installed
• Breadboard between (same effect)

Thanks for your help!

Answer 1

I can't help thinking that you've got a short or dodgy link in this somewhere.

I'd take off the PI, and test the board with a multi-meter in continuity mode. Check what happens when you wiggle the cables etc.

Any short or wrong link should then show up as long as you test logically