Failing to understand app_timer

[ImQ009]

Hello.

I cannot get my head around app_timers. After reading the docs, examples and answers on the devzone I'm still unable to get it running. The timeout callback isn't called after starting the timer. Any assistance, please?

app_timer_id_t timerFoo;

void foobarHandler(void *context)
{
	log("foobar\r\n");
}

int main()
{	
	uartInit();
	log("begin\r\n");
	
	APP_TIMER_INIT(0, 1, 4, NULL);
	if(app_timer_create(&timerFoo, APP_TIMER_MODE_SINGLE_SHOT, foobarHandler) != NRF_SUCCESS) log("creation failed\r\n");
	if(app_timer_start(timerFoo, APP_TIMER_TICKS(2000, 0), NULL) != NRF_SUCCESS) log("starting failed\r\n");
	
	return 0;
}

[RK]

You need to start a low frequency clock source - in that code, you don't.

[Vebjørn]

Your main-function returns shortly after starting the timer, causing the entire program to exit. You need a while-loop at the end to keep it alive

[ImQ009]

Oh, yeah, seems like I forgot about that when coding that testcase. Either way, that's not the problem. Adding a loop at the end doesn't solve it.

[ImQ009]

How do I do that though? Could you please point me to some info on that? By digging around I found this "nrf_drv_clock_init()" function. Is this it? It returns NRF_ERROR_SOFTDEVICE_NOT_ENABLED "sd_softdevice_enable()" seems like the thing I have to use here but I don't know what parameters I'm supposed to give it.

[RK]

You don't have a softdevice - so you need to just start an LF clock

nRF51_SDK_8.0.0/examples/peripheral/bsp/main.c

there's an example, there are lots.

The main function exiting isn't an issue. Just because you fall off the end of main() doesn't mean the CPU stops running, CPUs don't just .. stop. Normally it ends up in an exit loop just branching constantly to the same instruction, which is equivalent to adding a while().