GPIOTE rising and falling edge detection at the same time

RE: GPIOTE rising and falling edge detection at the same time

Jimmie Johansson — Sun, 23 Jan 2022 09:47:13 GMT

We re-designed the hardware and used the LPCOMP-module instead since the GPIOTE-function is not officially supported. We simply cannot risk edge-cases where it could fail. But the proof of concept was done directly with the nrfx-drivers (or direct register access, don't remember fully). We simply se up two different gpiote channels on the same pin.

RE: GPIOTE rising and falling edge detection at the same time

shna6159 — Sun, 23 Jan 2022 04:23:41 GMT

Hey Jimmie,

I saw that you implemented GPIOTE rising and falling edge detection at the same time. I am trying to implement something similar. Is it possible for you to share your implementation of the same?

Also, have you run into any sort of stability issues with this implementation?

RE: GPIOTE rising and falling edge detection at the same time

ovrebekk — Fri, 18 Sep 2020 08:54:29 GMT

Hi Jimmie

Essentially this wasn't identified as a requirement when the module was originally specified, and no one has gone through the loops of qualifying this use case later on.

Still, connecting two peripherals to the same pin has been shown to work fine if both or one of them are inputs only, but if both are set up as outputs then you will obviously have issues.

A workaround if you can spare a GPIO is to connect your signal to two different GPIO's at the same time, and assign one GPIOTE channel to each of them. Then you don't have to 'go against' the recommendation in the specification.

Alternatively this would have to be tested so we can guarantee that connecting two channels to the same pin will work fine, which needs to be prioritized towards other tasks the test group is working on. I can open an internal ticket to see if we can do this work, but I can't make any promises obviously.

Best regards
Torbjørn

RE: GPIOTE rising and falling edge detection at the same time

Jimmie Johansson — Thu, 17 Sep 2020 12:59:32 GMT

Thank you for the answer, can you give some more information on why it is not officially supported?

We are writing code for receiving critical alarms, so we would need to know some more specifics if we are going to ship a product using a non-supported feature. I have also confirmed that is seems to work as well as the analog comparator (the reason why I want to use GPIOTE is that the hardware design can be simplified if we can select any GPIO and not just the analog pins).

RE: GPIOTE rising and falling edge detection at the same time

ovrebekk — Thu, 17 Sep 2020 12:52:00 GMT

Hi Jimmie

While it isn't officially supported I have yet to notice any issues when connecting two GPIOTE channels in input mode to the same pin.

I have used this feature on a couple of occasions in applications where a separate event for the rising and falling edge is required, and it has worked fine during my testing at least.

So while I can't guarantee that this will work fine in all occasions there are no known issues using the GPIOTE in this way.

Best regards
Torbjørn