Why doesn't the uC STM32L431CCT6 exit standby mode with RTC wakeup event?

[ThorosOfMyr]

I have a STM32L431CCT6 uC configured with CubeMX (project attached): RTC connected to LSE 32.768 kHz, auto wake up enabled. In my code, I perform the following calls:

HAL_GPIO_WritePin(LED2_RESET_ESP32_GPIO_Port, LED2_RESET_ESP32_Pin, GPIO_PinState::GPIO_PIN_RESET);
HAL_PWREx_EnableInternalWakeUpLine();
result = HAL_RTCEx_SetWakeUpTimer(&hrtc, 0x0000FFFF, RTC_WAKEUPCLOCK_RTCCLK_DIV2);
if(result == HAL_OK)
{
    HAL_PWR_EnterSTANDBYMode();
}

The uC enters correctly the standby mode, it should wake up after 4 seconds, ma it never does. I tried to check if wake up interrupt is launched, removing the HAL_PWR_EnterSTANDBYMode() call, but handler code is never executed (no breakpoint hit, no led blinked).

[waclawek.jan]

> handler code is never executed

Then it's not standby-mode related, is it?

Read out and check/post content of RTC, EXTI, NVIC, and any other registers which may be related to wakeup.

JW

[ThorosOfMyr]

Yes, it looks like it's about the RTC wake up event. Accordingly also to AN4759, chapter 2.4, I can't find if there is anything wrong in my configuration.

RTC, NVIC and EXTI registers look ok.

[waclawek.jan]

> RTC, NVIC and EXTI registers look ok.

Post them.

JW

[ThorosOfMyr]

After init

[ThorosOfMyr]

before standby

[waclawek.jan]

Why are EXTI and RTC registers content not visible in the "before standby" file?

In the other file, RTC_CR is 0x403, i.e. WUTE is enabled but WUTIE is not. Quoting from RM:

> When the periodic wakeup interrupt is enabled by setting the WUTIE bit in the RTC_CR

> register, it can exit the device from low-power modes.

JW

[ThorosOfMyr · Accepted solution]

That was the problem, the WUTIE bit were not set, because HAL_RTCEx_SetWakeUpTimer just set up the timer but not the interrupt. If you need to set also the interrupt, HAL_RTCEx_SetWakeUpTimer_IT must be used.

[Tkumar.2]

STM32L431CCU6

can you please provide the schematics

[waclawek.jan]

Please start a new thread and post clearly your question there.

JW