STM32G0 race condition power-saving shutdown mode

[Kmax18]

I am looking for a software solution for this race condition:
* The power button is connected to both the On/Off pin PD3 and the wakeup pin PB5. See the partial schematic.
* The issue is that the STM32G0 enters shutdown mode, but immediately wakes up. Please see my function below.
What is missing? Thank you!

 

 

void Enter_Shutdown_Mode(void)
{
 sprintf(msgString, "Enter_Shutdown_Mode...\r\n");
 Debug_Print( msgString );
 HAL_Delay(50);

 /* Enable the Power Controller (PWR) APB clock */
 __HAL_RCC_PWR_CLK_ENABLE();

 /* Wait for the pin to be HIGH after the button release.
 If the power button is currently pressed (LOW), entering shutdown
 with "LOW" polarity will cause an instant restart. */
 while (HAL_GPIO_ReadPin(WAKEUP_GPIO_Port, WAKEUP_Pin) == GPIO_PIN_RESET)
 {
 // Wait for user to release the button
 HAL_Delay(10);
 }

 // Debounce the button press
 HAL_Delay(50);

 /* Clear the Wakeup Flag.
 If a flag is set from a previous wakeup, the MCU will fail to enter
 Shutdown and stay in Run mode. */
 __HAL_PWR_CLEAR_FLAG(PWR_FLAG_WUF6);

 /* Disable and re-enable the wakeup pin to ensure a clean start. */
 HAL_PWR_DisableWakeUpPin(PWR_WAKEUP_PIN6);
 HAL_PWR_EnableWakeUpPin(PWR_WAKEUP_PIN6_LOW);

 /* Enter Shutdown Mode:
 Set the LPMS bits in PWR_CR1 to '011' (Shutdown)
 Set the SLEEPDEEP bit in the Cortex-M0+ System Control Register
 Execute the WFI (Wait For Interrupt) instruction */
 HAL_PWREx_EnterSHUTDOWNMode();

 /* --- THE MCU IS NOW IN SHUTDOWN ---
 NOTE: After a wakeup from Shutdown, the MCU resets. The code below
 this line will NEVER execute. */
}

 

[TDK]

What is missing is disabling systick. Could be other things.

[Saket_Om]

Hello @Kmax18 

In addition to @TDK recommandation, you should:

1. Clear all relevant WUF flags (not just WUF6) before enabling the wakeup line.
2. Also clear the Standby/Shutdown flag if it’s set.

/* Enable PWR clock */
__HAL_RCC_PWR_CLK_ENABLE();

/* Clear all wakeup flags and shutdown/standby flags */
__HAL_PWR_CLEAR_FLAG(PWR_FLAG_WUF1 | PWR_FLAG_WUF2 | PWR_FLAG_WUF3 |
 PWR_FLAG_WUF4 | PWR_FLAG_WUF5 | PWR_FLAG_WUF6 |
 PWR_FLAG_SB);

In addition to