#78 'Conflicting edge' exception with GPIO.wait_for_edge()

[Ben Croston]

Occurs when waiting for a different edge type to the first time GPIO.wait_for_edge() was called.

[Ben Croston]

Fix pushed to source code library. Will be in next release.

[Ben Croston]

Bug found with the following code:

import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BCM)
GPIO.setup(23, GPIO.IN, pull_up_down = GPIO.PUD_DOWN)
while True:
   GPIO.wait_for_edge(23, GPIO.RISING)
   print("Button 1 Pressed")
   GPIO.wait_for_edge(23, GPIO.FALLING)
   print("Button 1 Released")

GPIO.cleanup()

This produces a continuous output of:
Button 1 Pressed
Button 1 Released
Button 1 Pressed
Button 1 Released
Button 1 Pressed
...etc.etc...

See http://www.raspberrypi.org/forums/viewtopic.php?f=66&t=88951

[Ben Croston]

Have added fix to get it to ignore the initial edge when changing edges. Fix is in source code library.

[Joel Ebel]

Perhaps I'm misunderstanding how this is to be used, but if I use your code above, but just trigger on a single GPIO.BOTH within the while loop, I get stuck in a continuous loop. I would have expected it to cycle the loop only when I press or release the button.

I ran some other tests. Any single wait_for_edge() in a loop starts a continuous loop as soon as the first matching edge is triggered. You have to wait for a different edge type in order for the first edge type to trigger again.

In my case, I really just want to trigger on falling to start a loop of code, but I need a way to reset it at the end of the loop without having to wait for rising again, since that might have happened while I was in the middle of the loop.

[Ben Croston]

Fixed in release 0.5.8

[human-being]

With 0.5.8-1, I get this now after one button press:

RuntimeError: Conflicting edge detection events already exists for this GPIO channel

No further button presses work. Should I open a new bug?