Issue on nputs capture of two pins simultaneously

RE: Issue on nputs capture of two pins simultaneously

cristian.anceschi — Mon, 25 Oct 2021 10:17:47 GMT

Hi Einar

Thanks for your hints.

As you suggested, I moved the clearing EVENT_PORT just after the EVENT_PORT check.

Moreover, I tried to leaver the code running inside the interrupt until both EVENT_IN flags are both zero.
This appears to reduce missed readings and any interruptions in measurements.

void GPIOTE_IRQHandler(void)
{
	bool EvntInRun = true;
	
	if(NRF_GPIOTE->EVENTS_PORT == 1)
		NRF_GPIOTE->EVENTS_PORT = 0;
	
	while(EvntInRun)
	{
		//--------------
		if(NRF_GPIOTE->EVENTS_IN[0] == 1)
		{
			CaptEvent(&SGN_In_1);
			NRF_GPIOTE->EVENTS_IN[0] = 0;
		}
		//--------------
		if(NRF_GPIOTE->EVENTS_IN[1] == 1)
		{
			CaptEvent(&SGN_In_2);
			NRF_GPIOTE->EVENTS_IN[1] = 0;
		}
		//--------------
		//NRF_GPIOTE->EVENTS_PORT = 0;
		
		if((NRF_GPIOTE->EVENTS_IN[0] == 0) && (NRF_GPIOTE->EVENTS_IN[1] == 0))
			EvntInRun	= false;
	}
}


Kind regards
Cristian

RE: Issue on nputs capture of two pins simultaneously

Einar Thorsrud — Mon, 18 Oct 2021 13:11:25 GMT

Hi,

I would think you could reduce this issue by clearing EVENTS_PORT before, so that you reduce the risk of missing an interrupt. So something like this:

void GPIOTE_IRQHandler(void)
{
	if(NRF_GPIOTE->EVENTS_PORT == 1)
	{
                NRF_GPIOTE->EVENTS_PORT = 0;
		//--------------
		if(NRF_GPIOTE->EVENTS_IN[0] == 1)
		{
			CaptEvent(&SGN_In_1);
			NRF_GPIOTE->EVENTS_IN[0] = 0;
		}
		//--------------
		if(NRF_GPIOTE->EVENTS_IN[1] == 1)
		{
			CaptEvent(&SGN_In_2);
			NRF_GPIOTE->EVENTS_IN[1] = 0;
		}
		//--------------
	}
}

That is also how it is done in the SDK driver (see modules\nrfx\drivers\src\nrfx_gpiote.c for reference).

You may see issue still sometimes though, so it could be that it would make sense to alternate between measuring the two input signals, rather that trying to measure both at the same time.