Unexpected Behavior with GPIO_INT_EDGE_BOTH Interrupt on Button Release in nRF Connect SDK

RE: Unexpected Behavior with GPIO_INT_EDGE_BOTH Interrupt on Button Release in nRF Connect SDK

Edvin — Wed, 15 Jan 2025 11:41:08 GMT

I guess that is correct. Most of our samples doesn't use this, since they use a custom library that you can find in:

NCS\nrf\lib\dk_buttons_and_leds.c

That also has a small (hardcoded) debounce of 1ms.

Best regards,
Edvin

RE: Unexpected Behavior with GPIO_INT_EDGE_BOTH Interrupt on Button Release in nRF Connect SDK

Andrea Verdecchia — Fri, 10 Jan 2025 15:03:10 GMT

Thank you for your suggestions, but I was hoping to avoid implementing software debounce, as I read here that Zephyr natively supports debounce, which should be set to 30ms by default. Am I wrong, or is this correct? Also, as you’ve already noticed, the callback invocation pattern is always the same, so it doesn’t seem like a coincidence that I always get the 1-0 sequence when releasing the button.

RE: Unexpected Behavior with GPIO_INT_EDGE_BOTH Interrupt on Button Release in nRF Connect SDK

Edvin — Fri, 10 Jan 2025 14:38:05 GMT

Hello,

What you are seeing is probably a bounce. It is however, a little bit strange if it is consistent in the pattern that you are seeing. Is it always like that, or is it a coincidence that you always get one touchState 1 before the touchState 0 in your log?

Either way, I would say that a small debounce would do the trick here. You can introduce a small delay before you read the pin state. You can see an example on how this is done in the dk_buttons_and_leds.c in NCS (ncs\nrf\lib\dk_buttons_and_leds\dk_buttons_and_leds.c), where they use k_work_reschedule to scan the buttons 1ms later.

Alternatively, you can do something like this, and use a timer to check that the button was held for at least some time, to rule out the bounce signals:

devzone.nordicsemi.com/.../3175.long_5F00_press_5F00_v2.zip

Here the "debounce" is set to 10 seconds, so that is really more of a long press detection. But if you set it to something like 100ms or 50ms, it would act more like a debounce.

Another alternative is to add some passive components (capacitor) close to the button pin, so that the signal doesn't bounce as much when the button is being pressed.

Best regards,

Edvin