[stm32u585] wakeup failed from standby mode, "Wait till LSI is disabled" timeout in HAL_RCC_OscConfig()

[lll]

hello,

I encountered a problem while developing for stm32u585. When the stm32 wakes up from standby mode, the HAL_RCC_OscConfig() function occasionally fails, "Wait till LSI is disabled" timeout in HAL_RCC_OscConfig() (this project uses IWDG)
The specific process is as follows:

1. start boot
 HAL_Init();
 SystemClock_Config();
 MX_GPIO_Init();
 MX_ICACHE_Init();
 MX_UART4_Init();
 boot to other address(app)
2. app init
 HAL_Init();
 SystemClock_Config();
 RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI48|RCC_OSCILLATORTYPE_LSI
 |RCC_OSCILLATORTYPE_HSE|RCC_OSCILLATORTYPE_LSE;
 RCC_OscInitStruct.HSEState = RCC_HSE_ON;
 RCC_OscInitStruct.LSEState = RCC_LSE_ON_RTC_ONLY;
 RCC_OscInitStruct.HSI48State = RCC_HSI48_ON;
 RCC_OscInitStruct.LSIState = RCC_LSI_ON;
 RCC_OscInitStruct.LSIDiv = RCC_LSI_DIV128;
 RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
 RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
 RCC_OscInitStruct.PLL.PLLMBOOST = RCC_PLLMBOOST_DIV1;
 RCC_OscInitStruct.PLL.PLLM = 1;
 RCC_OscInitStruct.PLL.PLLN = 40;
 RCC_OscInitStruct.PLL.PLLP = 2;
 RCC_OscInitStruct.PLL.PLLQ = 2;
 RCC_OscInitStruct.PLL.PLLR = 2;
 RCC_OscInitStruct.PLL.PLLRGE = RCC_PLLVCIRANGE_1;
 RCC_OscInitStruct.PLL.PLLFRACN = 0;
 if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
 {
 Error_Handler();
 }
3. timeout in HAL_RCC_OscConfig()
 /* Turn off LSI before changing RCC_BDCR_LSIPREDIV */
 if ((bdcr_temp & RCC_BDCR_LSION) == RCC_BDCR_LSION)
 {
 __HAL_RCC_LSI_DISABLE();

 tickstart = HAL_GetTick();

 /* Wait till LSI is disabled */
 while (READ_BIT(RCC->BDCR, RCC_BDCR_LSIRDY) != 0U)
 {
 if ((HAL_GetTick() - tickstart) > LSI_TIMEOUT_VALUE)
 {
 return HAL_TIMEOUT;
 }
 }
 }

How to solve this problem

 

[Saket_Om]

Hello @lll 

The LSI should only be initialized once at power-on reset (POR). Re-initializing or reconfiguring the LSI after each wake-up from standby can cause issues, as the oscillator may already be in use by IWDG, and the LSIRDY flag may not behave as expected.

[lll]

Does this mean I have to modify HAL_RCC_OscConfig() ?

I have added this condition in HAL_RCC_OscConfig():

__HAL_PWR_GET_FLAG(PWR_FLAG_SBF)

Can it ensure that this startup is from standby wake-up

/*------------------------------ LSI Configuration -------------------------*/
 if ((((pRCC_OscInitStruct->OscillatorType) & RCC_OSCILLATORTYPE_LSI) == RCC_OSCILLATORTYPE_LSI)
 && __HAL_PWR_GET_FLAG(PWR_FLAG_SBF))