IWDG Early Interrupt Not Working on STM32 NUCLEO-U385RG-Q

[vijayrakesh13]

Hi everyone, I'm building a watchdog application on the STM32 NUCLEO-U385RG-Q using the Arduino IDE and the IWatchdog library. Since the library doesn’t support early interrupt callbacks, I modified it by adding some LL code (after LL_IWDG_SetPrescaler()) inside IWatchdogClass::set() as shown below. However, the early interrupt doesn’t trigger. Am I missing something, like NVIC config or enabling the interrupt line?

// Enable IWDG EWI in IWatchdog.cpp LL_IWDG_SetEwiTime(IWDG, (uint32_t)1500); LL_IWDG_EnableIT_EWI(IWDG);

#include <IWatchdog.h> extern "C"{ #include <stm32u3xx_ll_iwdg.h> #include <stm32u3xx.h> } extern "C" void IWDG_IRQHandler (void){ Serial.println("Wake up Interrupt"); } #ifdef USER_BTN const int buttonPin = USER_BTN; #else const int buttonPin = 2; #endif #ifdef LED_BUILTIN const int ledPin = LED_BUILTIN; #else const int ledPin = 13; #endif static int default_buttonState = LOW; void setup() { pinMode(ledPin, OUTPUT); pinMode(buttonPin, INPUT); Serial.begin(115200); Serial.println("Init"); if (IWatchdog.isReset(true)) { // LED blinks to indicate reset for (uint8_t idx = 0; idx < 5; idx++) { digitalWrite(ledPin, HIGH); delay(100); digitalWrite(ledPin, LOW); delay(100); } } // Read default state of the pushbutton default_buttonState = digitalRead(buttonPin); // Enable EWI __enable_irq(); // Enables global interrupts HAL_NVIC_SetPriority(IWDG_IRQn, 0, 0); HAL_NVIC_EnableIRQ(IWDG_IRQn); IWatchdog.begin(10000000); Serial.print("EWI value: "); Serial.println(LL_IWDG_GetEwiTime(IWDG)); if (!IWatchdog.isEnabled()) { // LED blinks indefinitely while (1) { digitalWrite(ledPin, HIGH); delay(500); digitalWrite(ledPin, LOW); delay(500); } } } void loop() { // Compare current button state of the pushbutton value: if (digitalRead(buttonPin) == default_buttonState) { digitalWrite(ledPin, LOW); } else { digitalWrite(ledPin, HIGH); // Reload the watchdog only when the button is pressed IWatchdog.reload(); } }

Any tips or examples would be greatly appreciated.

Thanks,
Rakesh

[vijayrakesh13]

LL_IWDG_SetEwiTime() overwrites the register when it is enabled and clears the EWI interrupt bit.

[fpistm]

Hi @vijayrakesh13
Thanks for the feedback.
If you think it is a good addition, feel free to provide a PR to add this feature to the library.