STM32L476 RTC Wake Up interrupt triggered only after another interrupt has been triggered

[YBrun.1849]

Hello,

I'm exploring the low power modes with a NUCLEO-L476RG (STM32L476RG).

I generated RTC and NVIC configurations with STM32CubeMX (5.3 and then 5.6).

I am able to wake up from STOP0, STOP1 and STOP2 using the GPIO EXTI interrupt of the user button.

I am able to wake up from SHUTDOWN using the RTC Wake Up interrupt.

I am, however, not able to wake up from STOP0/1/2 and STANDBY using the RTC Wake Up interrupt. The STM32L476 stays forever in the selected low power mode, until I trigger a GPIO EXTI interrupt with the user button (in STOP0/1/2 modes). After this "release", the RTC Wake Up interrupt works correctly and is able to wake up the STM32L476 at the chosen interval.

Do you have any idea from what this problem may come?

Obviously, as interrupts are anyway sooner or later functioning, the NVIC and RTC configurations are correctly made (thanks CubeMX).

[waclawek.jan]

And what if you *don't* use the GPIO EXTI, only the RTC wakeup?

Wakeup from RTC Alarm works?

Read out and check the relevant RTC, EXTI and NVIC registers, just before going to stop.

JW