How to check for pending interrupts before calling sd_app_evt_wait?

[Collin]

Hi. I am having trouble getting the sd_app_evt_wait() call to work correctly in my code. My main program works like this:

<inits>
for(;;)
{
   <read saadc>
   <sd_app_evt_wait> // app_timer should make this return in 10 seconds
}

I have an app_timer that causes sd_app_evt_wait to return by firing every 10 seconds. The problem is, after sampling the ADCs, the call to sd_app_evt_wait returns immediately, running the loop forever. It doesn't sleep and wait for the timer. If I put a second call to sd_app_evt_wait directly after the first, the first call returns, and the second call sleeps until the timer wakes it (desired operation, but with two calls). From what I have learned of the sd_app_evt_wait function, if there are pending interrupts, it will immediately return. However, if I read the NVIC->ISPR at any time, it is 0. No interrupts pending, but sd_app_evt_wait returns once, then sleeps properly, on the Second call. I read about the FPU interrupts, so I added the following:

 uint32_t FPU_EXCEPTION_MASK = 0x0000009F;
pending = __get_FPSCR();
if (pending)
{
	NRF_LOG_DEBUG("FPU Exceptions: %d\r\n", pending);
	/* Clear exceptions and PendingIRQ from the FPU unit */
	__set_FPSCR(__get_FPSCR() & ~(FPU_EXCEPTION_MASK));
	(void) __get_FPSCR();
	NVIC_ClearPendingIRQ(FPU_IRQn);
}

but they don't help. The variable "pending" is always 0, and the ISPR is always 0. Adding

NVIC_ClearPendingIRQ(SAADC_IRQn);
NVIC_ClearPendingIRQ(FPU_IRQn);

before the first call to sd_app_evt_wait doesn't help either. What am I missing?

[Collin]

NVIC->ISER value is 0x3520981 with SAADC enabled, and 0x3520901 without it enabled. It will sleep properly with one call to sd_app_evt_wait() if I comment out the ADC init and polling. However, the only time the callback in the SAADC is called is after calibration, on init. It seems that, just because the SAADC interrupt is enabled, I have to call sd_app_evt_wait() twice.

[run_ar]

Have you tried using the Softdevice NVIC API. You can find more information on the Interrupt model here.

[Collin]

Thanks for the tip on the softdevice NVIC wrappers! I tried this code in the main loop, just before attempting to sleep:

for (uint8_t i = 0; i < (FPU_IRQn+1); i++)
			{
				uint32_t ret = sd_nvic_GetPendingIRQ(i, &pending);
				if ((NRF_SUCCESS == ret) && pending)
				{
					NRF_LOG_DEBUG("Pending set interrupt from SD: 0x%X\r\n", i);
				}
			}

but it never got a pending interrupt. The very next call in the code is to sd_app_evt_wait(), and that returns and runs the loop again. Then, the second time, it sleeps.

[run_ar]

Which version of the S132 are you using?

[Collin]

SDK 12.1.0 softdevice s123 v3.0.0, using the precompiled hex from the SDK folder.