Read gpio state on event

RE: Read gpio state on event

Sigurd — Fri, 08 Mar 2019 15:01:41 GMT

[quote userid="7065" url="~/f/nordic-q-a/44535/read-gpio-state-on-event/174898"]it has same effect as reading gpio state in interrupt routine (which has some latency due to softdevice).[/quote]

You can increment the timer counter with PPI using the Timer's "TASKS_COUNT" task.

RE: Read gpio state on event

gaminn — Thu, 07 Mar 2019 19:45:21 GMT

Actually, I found that this idea doesn't work - it has same effect as reading gpio state in interrupt routine (which has some latency due to softdevice). Now I'm trying this: on A channel's rising/falling edge I trigger SPI transaction (B channel connected to MISO). SPI samples B channel and stores it value (0xFF or 0x00) to RX buffer where it is accessible later. The same "principle" would probably work with ADC - to buffer B channel using ADC on A channel falling/rising edge.

RE: Read gpio state on event

gaminn — Thu, 07 Mar 2019 16:06:00 GMT

Great idea, thanks. The only drawback in my case is that I might run out of timers.

RE: Read gpio state on event

Sigurd — Thu, 07 Mar 2019 15:46:33 GMT

Hi,

You can configure the GPIOTE to generate an event on GPIO rising edge, falling edge or any change. You can then configure an TIMER instance in counter mode, and use it to keep track of how many times the event has been generated. If you know the initial gpio state(high/low), then you also know the current GPIO state simply by looking at the counter value.