nrf_pwr_mgmt_run() with SoftDevice not go to low power

RE: nrf_pwr_mgmt_run() with SoftDevice not go to low power

Jared — Mon, 27 Jul 2020 12:59:15 GMT

Hi,

Thank you for your observations.

Could you upload a minimal project that reproduces the issue and will run on the nRF52840 DK? I'll try to reproduce it and see if I can find the root cause.

best regards

Jared

RE: nrf_pwr_mgmt_run() with SoftDevice not go to low power

Bar — Mon, 27 Jul 2020 12:41:48 GMT

Hi Jared.

I found also something strange about implement the _WFE()

In some examples I found it set like this

__WFE();

__SEV();
__WFE();

but using it won't get it to low power

But know during reading about sd_app_evt_wait();

I found it is written like this

__SEV();
__WFE();

__WFE();

This one work.

So maybe inside sd_app_evt_wait();

It still use the wrong setting

__WFE();

__SEV();
__WFE();

(I can't look inside this function at my SDK)?

Bar.

RE: nrf_pwr_mgmt_run() with SoftDevice not go to low power

Bar — Mon, 27 Jul 2020 12:04:30 GMT

Hello Jared.

As I look into sd_app_evt_wait() I just get to this function

SVCALL(SD_APP_EVT_WAIT, uint32_t, sd_app_evt_wait(void));

But can't get inside. It is look it send and receive interrupt flags from the SD.

I look on the header explain and I see this:

In order to wake up from disabled interrupts, the SEVONPEND flag has to be set in the Cortex-M
MCU's System Control Register (SCR), CMSIS_SCB.

... The application must ensure that the pended flag is cleared using ::sd_nvic_ClearPendingIRQ
in order to sleep using this function. This is only necessary for disabled interrupts

I can't find anything about sd_nvic_ClearPendingIRQ

But when look for the SEVONPEND flag I found this discussion: https://devzone.nordicsemi.com/f/nordic-q-a/7107/sevonpend-setting---how-to

WHere he did some work exactly with the some function I try to handle.

Where look for https://devzone.nordicsemi.com/f/nordic-q-a/7107/sevonpend-setting---how-to

So I look for SCB_SCR_SEVONPEND_Msk and the only thing I found was

SCB->SCR |= SCB_SCR_SEVONPEND_Msk;

which is close by #ifdef PWR_MGMT_SLEEP_IN_CRITICAL_SECTION_REQUIRED

DO I need to open this define?

I also read comment exactly about some issue with sd_app_evt_wait(void) and excessive current. They all take about the FPU and its interrupt panding. https://devzone.nordicsemi.com/f/nordic-q-a/13670/solved-nrf52-sd_app_evt_wait-will-not-go-to-sleep

But I try some like

  // Set bit 7 and bits 4..0 in the mask to one (0x ...00 1001 1111)
  #define FPU_EXCEPTION_MASK 0x0000009F 

      /* Clear exceptions and PendingIRQ from the FPU unit */
      __set_FPSCR(__get_FPSCR()  & ~(FPU_EXCEPTION_MASK));      
      (void) __get_FPSCR();
      NVIC_ClearPendingIRQ(FPU_IRQn);
before

error_code = sd_app_evt_wait();
but didn't help.
What could be the problem?
Regards
Bar.

RE: nrf_pwr_mgmt_run() with SoftDevice not go to low power

Jared — Mon, 27 Jul 2020 08:03:51 GMT

Hi,

Sorry for the confusion, you're absolutely correct. Does it go to the WFE() inside the sd_app_evt_wait()?

RE: nrf_pwr_mgmt_run() with SoftDevice not go to low power

Bar — Sun, 26 Jul 2020 07:07:53 GMT

Hi Jored.

It doesn't stop there because I enable the BLE and the softdevice define SOFTDEVICE_PRESENT. So it go to sd_app_evt_wait()

Look at the code.

// Wait for an event.
#ifdef SOFTDEVICE_PRESENT
if (nrf_sdh_is_enabled())
{
ret_code_t ret_code = sd_app_evt_wait();
ASSERT((ret_code == NRF_SUCCESS) || (ret_code == NRF_ERROR_SOFTDEVICE_NOT_ENABLED));
UNUSED_VARIABLE(ret_code);
}
else
#endif // SOFTDEVICE_PRESENT
{
// Wait for an event.
__WFE();
// Clear the internal event register.
__SEV();
__WFE();
}

As I see it when it use BLE with SOFTDEVICE and it is enable it should go there.

Is there a problem about it?

Bar.

RE: nrf_pwr_mgmt_run() with SoftDevice not go to low power

Jared — Fri, 24 Jul 2020 07:56:24 GMT

Hi,

Use a debugger and set a breakpoint inside nrf_pwr_mgmt_run() at line 359 and see if the program hits the breakpoint.

RE: nrf_pwr_mgmt_run() with SoftDevice not go to low power

Bar — Wed, 22 Jul 2020 11:43:16 GMT

Hi Jared.

I use my own board where I have a peripheral that take extra power. With __WFI() I get 2ma. With nrf_pwr_mgmt_run() I get about 8ma.

The relevant code is as follow

#if ((OS_VIEW_IFSELECT != OS_VIEW_IF_JLINK) && (OS_DEBUG == 0))
        if (IdleTicks > 2) // nothing to do wait for interrupt at run time
		{
			// Switch CPU into sleep mode
			nrf_pwr_mgmt_run();
		}

#endif

RE: nrf_pwr_mgmt_run() with SoftDevice not go to low power

Jared — Wed, 22 Jul 2020 11:26:25 GMT

Hi,

How are you determining that the device doesn't go into sleep and are you using a custom board?

Please provide more information regarding your application such as code.

best regards

Jared