Wake-up form EXTI not working on STM32G0B1 custom board

[WrenchInTheWorks]

Hello,

I'm attempting to make my MCU shift between STOP and RUN mode using a button. When I press the button the CPU stops, however, upon pressing again it fails to start the CPU. I know this form the LED indicators.

The strange part is that when I place a debug point, or anything debug related, the CPU wakes and immediately and runs the ISR as if it were waiting for the stop mode to resume.

Is there some setting I need to enable to get the GPIOs to funtion in stop0? 

I have had a look at other forum posts and MX examples but have not seen anything, or I have missed it.

My ISR:

void HAL_GPIO_EXTI_Falling_Callback(uint16_t GPIO_Pin) {
    if (GPIO_Pin == Button_Pin && powerDownState == 0)
    {
    	powerDownState = 1;

    	HAL_GPIO_WritePin(Green_LED_GPIO_Port,Green_LED_Pin, GPIO_PIN_RESET); // Enable pull-up on button

        HAL_SuspendTick();
        HAL_PWR_EnterSTOPMode(PWR_MAINREGULATOR_ON, PWR_STOPENTRY_WFI);
    }
    else
    {
    	HAL_ResumeTick();

        powerDownState = 0;

        HAL_GPIO_WritePin(Green_LED_GPIO_Port, Green_LED_Pin, GPIO_PIN_SET);
    }
}

GPIO_Init:

void MX_GPIO_Init(void)
{

  GPIO_InitTypeDef GPIO_InitStruct = {0};

  /* GPIO Ports Clock Enable */
  __HAL_RCC_GPIOB_CLK_ENABLE();
  __HAL_RCC_GPIOA_CLK_ENABLE();
  __HAL_RCC_GPIOD_CLK_ENABLE();

  /*Configure GPIO pin Output Level */
  HAL_GPIO_WritePin(Green_LED_GPIO_Port, Green_LED_Pin, GPIO_PIN_RESET);

  /*Configure GPIO pin Output Level */
  HAL_GPIO_WritePin(Button_Drive_GPIO_Port, Button_Drive_Pin, GPIO_PIN_RESET);

  /*Configure GPIO pin : Green_LED_Pin */
  GPIO_InitStruct.Pin = Green_LED_Pin;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
  HAL_GPIO_Init(Green_LED_GPIO_Port, &GPIO_InitStruct);

  /*Configure GPIO pin : Button_Pin */
  GPIO_InitStruct.Pin = Button_Pin;
  GPIO_InitStruct.Mode = GPIO_MODE_IT_FALLING;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  HAL_GPIO_Init(Button_GPIO_Port, &GPIO_InitStruct);

  /*Configure GPIO pin : Button_Drive_Pin */
  GPIO_InitStruct.Pin = Button_Drive_Pin;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
  HAL_GPIO_Init(Button_Drive_GPIO_Port, &GPIO_InitStruct);

  /* EXTI interrupt init*/
  HAL_NVIC_SetPriority(EXTI2_3_IRQn, 3, 0);
  HAL_NVIC_EnableIRQ(EXTI2_3_IRQn);

}

Cheers,
Michael

[TDK · Accepted solution]

Don't enter stop mode within an interrupt. The interrupt can't pre-empt itself.

Set a flag and handle going to sleep within the main loop.

[MM..1]

Use STOP in ISR callback is possible only with good knowledge and prepare registers state ... As @TDK  write never doit this way...