GPIOTE Interrupt

RE: GPIOTE Interrupt

yd — Thu, 09 Oct 2014 06:33:57 GMT

It looks like the values are being read after the GPIOTE task 1 has completed. Make sure you don't put any breakpoints in the GPIOTE_IRQHandler before reading the values of CC[0] / CC[1]. Check below for breakpoint positioning.

From the documentation of GPIOTE abstraction:

The GPIOTE users are responsible for configuring all their corresponding pins, except the SENSE field, which should be initialized to GPIO_PIN_CNF_SENSE_Disabled.

Although you are not using the abstraction, it might have to do something with Sense Low. I don't configure the sense field in my project, so I am not sure about this.

Try changing:

nrf_gpio_cfg_sense_input(ECHO, NRF_GPIO_PIN_NOPULL, NRF_GPIO_PIN_SENSE_LOW);

To:

nrf_gpio_cfg_input(ECHO, NRF_GPIO_PIN_NOPULL);

Enable Interrupts on GPIOTE after you have cleared the pending flags like this:

NVIC_DisableIRQ(GPIOTE_IRQn);
NVIC_ClearPendingIRQ(GPIOTE_IRQn);

NRF_GPIOTE->INTENSET = 0x00000001;// enable interrupts for config[n] pins, n = 0 in this case so bitmask is 0x01

NVIC_SetPriority(GPIOTE_IRQn, 3); //optional: set priority of interrupt
NVIC_EnableIRQ(GPIOTE_IRQn);

Try to separate GPIOTE events in GPIOTE_IRQHandler and put breakpoints after reading CC values:

if(NRF_GPIOTE->EVENTS_IN[0] == 1)
{
	curr_cc0 = NRF_TIMER1->CC[0];
	curr_cc1 = NRF_TIMER1->CC[1]; //keep this if you need it
	NRF_GPIOTE->EVENTS_IN[0] = 0;  //this is where you should set breakpoint to make sure CC[0] and cc[1] don't change while you are in breakpoint
}

if(NRF_GPIOTE->EVENTS_IN[1] == 1) //will run only if you intenset event 1
{
	curr_cc0 = NRF_TIMER1->CC[0]; //keep this if you need it
	curr_cc1 = NRF_TIMER1->CC[1];
	NRF_GPIOTE->EVENTS_IN[1] = 0;  //this is where you should set breakpoint to make sure CC[0] and cc[1] don't change while you are in breakpoint
}

RE: GPIOTE Interrupt

Jose Xavier — Wed, 08 Oct 2014 09:21:49 GMT

I'm trying to capture the signal that you see in channel 2 of logic analyser screenshot. So I set up a gpiote task to lowtohigh event the save the timer1 count on cc[0] and another gpiote task to hightolow event that save the value on cc[1].

On the gpiote init I enable an interrupt for the lowtohigh event and debugging the code with a breakpoint on the gpioteirqhandler I would expect to got 0 on the cc[1] instead of the hightolow value.

RE: GPIOTE Interrupt

Stefan Birnir Sverrisson — Wed, 08 Oct 2014 09:04:22 GMT

I suspect that you are trying to build upon the gpiote_example in the nRF51 SDK. For setup of interrupts and interrupt handler, you might also benefit of looking at e.g. the rtc_example in the SDK.

I am also pretty unsure of what you are trying to achieve, so please clarify your problem.

You have not shown in your code your Timer configuration. TIMER1->CC[0] and TIMER1->CC[1] values should be the same as you set them when you initialize the timer. How it works is that you set a CC[X] compare register and then you start the TIMER. When the TIMER value is equal to the CC[X] value, a timer event is generated. Perhaps these simple timer examples will help you if you have doubts about how the TIMER actually works. Timer information is also available in the nRF51 Series Reference Manual.