LowPower.shutdown(1000); does not work as expected

[alexceltare2]

Describe the bug
The MCU should wake up after the RTC Timer interrupt tick but it doesn't. LED stays off on this mode. Other modes like LowPower.idle(1000), LowPower.sleep(1000), LowPower.deepSleep(1000) work as intended.

Steps to reproduce the behavior:

void loop() {
digitalWrite(LED_BUILTIN, HIGH);
LowPower.shutdown(1000);
digitalWrite(LED_BUILTIN, LOW);
LowPower.shutdown(1000);
}

Expected behavior
LED Blinks every 1000ms.

Desktop (please complete the following information):

• OS: Windows
• Arduino IDE version: 2.3.5
• STM32 core version: 2.10.1
• Library version: latest
• Tools menu settings if not the default:
• Upload method: Mass Storage

Hardware (please complete the following information):

• Board Name: Nucleo U385RG-Q

[fpistm]

Hi @alexceltare2
This is normal the LED never blink. When you exit the shutdown mode, the board simply reset (restart).

[fpistm]

Anyway after doing a test it seems the shutdown does not works.
I've made a fix in the STM32RTC:
stm32duino/STM32RTC#119

[alexceltare2]

But even this didn't work:

void loop() {
digitalWrite(LED_BUILTIN, HIGH);
delay(1000);
digitalWrite(LED_BUILTIN, LOW);
LowPower.shutdown(1000);
}

Assuming LowPower.shutdown(1000); will put the CPU into sleep for 1 second then reset.

[fpistm]

With the fix in the RTC it works :)
If you can test on your side and give feedback, it would be really appreciated.

[alexceltare2]

Yes, I've tested it with my U3 and works well now. Thanks!

[fpistm]

Welcome.