STM32WL immediately wakes from shutdown sleep mode

[Todd Rylaarsdam]

I'm attempting to cause an STM32WL (currently on a WL55JC1 devboard) to sleep using the shutdown mode, and am running into a an issue where the MCU immediately exits sleep after it enters it.

Here's what I believe to be the sleep related portions of my code - I can post more if needed:

int main(void)
 
{
 
 HAL_Init();
 
 HAL_PWR_EnableBkUpAccess();
 
 uint32_t tickstart = HAL_GetTick();
 
 HAL_StatusTypeDef ret = HAL_OK;
 
  while (!(READ_BIT(PWR->CR1, PWR_CR1_DBP) == (PWR_CR1_DBP)))
 
  {
 
   if ((HAL_GetTick() - tickstart) > RCC_DBP_TIMEOUT_VALUE)
 
   {
 
    ret = HAL_TIMEOUT;
 
    break;
 
   }
 
  }
 
  __HAL_RCC_BACKUPRESET_FORCE();  //[JT] - Debug
 
  __HAL_RCC_BACKUPRESET_RELEASE(); //[JT] - Debug
 
  HAL_PWR_DisableBkUpAccess();
 
 
 
  SystemClock_Config();
 
 
 
 
 
 MX_GPIO_Init();
 
 MX_RTC_Init();
 
 MX_SUBGHZ_Init();
 
 MX_USART2_UART_Init();
 
 MX_SubGHz_Phy_Init();
 
 /* USER CODE BEGIN 2 */
 
 HAL_UART_Receive_IT(&huart2, Rx_data, 1);
 
 
 
 if (__HAL_PWR_GET_FLAG(PWR_FLAG_SB) != RESET)
 
 {
 
  /* Clear Standby flag */
 
  __HAL_PWR_CLEAR_FLAG(PWR_FLAG_SB);
 
  printf("wakeup from stdby");
 
  // HAL_PWR_DisableWakeUpPin(PWR_WAKEUP_PIN1);
 
 
 
 }
 
 
 
 
 
 while (1)
 
 {
 
  HAL_Delay(5000);
 
	printf("going to sleep \n");
 
	HAL_Delay(3000);
 
	HAL_SuspendTick();
 
	HAL_PWREx_EnterSHUTDOWNMode();
 
	HAL_ResumeTick();
 
 }
 
}
 

When going into sleep, I attempt to suspend the systick, and then use the HAL macro to enter the shutdown sleep mode. From what I've read this seems to be all I need, but obviously not in this case. 

The exit from sleep happens regardless of the onboard ST-Link module on my devboard being powered or not.

NRST is currently floating, since when I pull it to ground the chip shuts down and pulls 700uA. Another puzzle to figure out.

Edit: Not sure if it will help, but here's my system clock config:

void SystemClock_Config(void)
 
{
 
 RCC_OscInitTypeDef RCC_OscInitStruct = {0};
 
 RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
 
 
 
 /** Configure LSE Drive Capability
 
 */
 
 HAL_PWR_EnableBkUpAccess();
 
 __HAL_RCC_LSEDRIVE_CONFIG(RCC_LSEDRIVE_LOW);
 
 /** Configure the main internal regulator output voltage
 
 */
 
 __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);
 
 /** Initializes the CPU, AHB and APB busses clocks
 
 */
 
 RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_LSE|RCC_OSCILLATORTYPE_MSI;
 
 RCC_OscInitStruct.LSEState = RCC_LSE_ON;
 
 RCC_OscInitStruct.MSIState = RCC_MSI_ON;
 
 RCC_OscInitStruct.MSICalibrationValue = RCC_MSICALIBRATION_DEFAULT;
 
 RCC_OscInitStruct.MSIClockRange = RCC_MSIRANGE_11;
 
 RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
 
 if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
 
 {
 
  Error_Handler();
 
 }
 
 /** Configure the SYSCLKSource, HCLK, PCLK1 and PCLK2 clocks dividers
 
 */
 
 RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK3|RCC_CLOCKTYPE_HCLK
 
               |RCC_CLOCKTYPE_SYSCLK|RCC_CLOCKTYPE_PCLK1
 
               |RCC_CLOCKTYPE_PCLK2;
 
 RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_MSI;
 
 RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
 
 RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
 
 RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
 
 RCC_ClkInitStruct.AHBCLK3Divider = RCC_SYSCLK_DIV1;
 
 
 
 if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK)
 
 {
 
  Error_Handler();
 
 }
 
}
 

[Todd Rylaarsdam]

Still stumped on this one. I'm able to get to a "sleep" state using this code below, but its still pulling 3.1mA of current.

					Radio.Sleep();
					HAL_SUBGHZ_MspDeInit(&hsubghz);
					LL_RCC_RF_EnableReset();
					__disable_irq();
					HAL_SuspendTick();
					HAL_PWREx_DisableSRAMRetention();
					HAL_PWREx_EnableFlashPowerDown(PWR_FLASHPD_LPSLEEP);
 
					HAL_PWREx_EnterSHUTDOWNMode();

(sorry for formatting, pasting from CubeIDE into the code snippet box causes issues)