STM32WB15x - LSE get stuck at startup

[freecoder]

Hi,

We're faced to a problem when dealing with LSE clock to handle RTC backup using a supercapa connected to the VBAT pin.

 

The LSE configuration under STM32CubeIDE:

 

 

The Clock Configuration function:

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);

 /** Initializes the RCC Oscillators according to the specified parameters
 * in the RCC_OscInitTypeDef structure.
 */
 RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI|RCC_OSCILLATORTYPE_LSI1
 |RCC_OSCILLATORTYPE_HSE|RCC_OSCILLATORTYPE_LSE;
 RCC_OscInitStruct.HSEState = RCC_HSE_ON;
 RCC_OscInitStruct.LSEState = RCC_LSE_ON;
 RCC_OscInitStruct.HSIState = RCC_HSI_ON;
 RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
 RCC_OscInitStruct.LSIState = RCC_LSI_ON;
 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_HCLK4|RCC_CLOCKTYPE_HCLK2
 |RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
 |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
 RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSE;
 RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
 RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
 RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
 RCC_ClkInitStruct.AHBCLK2Divider = RCC_SYSCLK_DIV1;
 RCC_ClkInitStruct.AHBCLK4Divider = RCC_SYSCLK_DIV1;

 if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_1) != HAL_OK)
 {
 Error_Handler();
 }
}

 

And when we started the program we get stuck at this line and then it goes in a timeout error:

We noticed that we get this issue only when the VBAT pin is set to 3v. 

Can you please give us a feedback and tell us we figure out the issue.

 

Thanks by advance.

Regards,

 

 

 

 

[STTwo-32]

Hello @freecoder 

On the clock configuration function, could you please try to change 

__HAL_RCC_LSEDRIVE_CONFIG(RCC_LSEDRIVE_LOW);

To

__HAL_RCC_LSEDRIVE_CONFIG(RCC_LSEDRIVE_HIGH);

Best Regards.

STTwo-32 

[freecoder]

Hello @STTwo-32 ,

Thank you for your response.

We made changes as you asked but nothing happened and still get stuck at same line of code.

 

Best Regards,

[freecoder]

Hi,

Is there any updates ?

Thanks,

Best regards

[freecoder]

Hi @STTwo-32 , 

It looks like when using these parameters it no more get stuck (disable the LSI):

 /** Initializes the RCC Oscillators according to the specified parameters
 * in the RCC_OscInitTypeDef structure.
 */
 RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI|RCC_OSCILLATORTYPE_HSE
 |RCC_OSCILLATORTYPE_LSE;
 RCC_OscInitStruct.HSEState = RCC_HSE_ON;
 RCC_OscInitStruct.LSEState = RCC_LSE_ON;
 RCC_OscInitStruct.HSIState = RCC_HSI_ON;
 RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
 RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
 if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)

 

Regards,