STM32H747 not starting with battery connected to vbat

[kens0o]

Hello,

I can't figure out why the STM32H747I-DISCO does not start when I connect an CR2032 Battery to vbat.

After turning the external powersupply off and on again, nothing happens and the debugger is disconnected.

So I can't easily debug where exactly the problem is, maybe i will use some uart messages later.

But when I push the reset button, it starts. Could this be a powerramp problem with my external supply?

Also when I remove the battery it starts just fine.

I fount this hint, but nothing happens after 30 seconds:

when STM32 wakes up or powers on with Backup Domain supplied by external battery and RTC running, the standard initialization routine of LSE may time out due to the fact that LSE is already running. If you don't test LSE\RTC operation prior to (re)initializing it, the timeout delay may be around 30 seconds.

So I changed the initialision code accordingly, like it did with the RTC before (checking the backupregister).

But it didn't help, maybe there is a mistake in the code?

 I also tried without the if condition in line 19, but I think the one in line 47 is what is recommended in the hint.

void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
 
  /** Supply configuration update enable
  */
  HAL_PWREx_ConfigSupply(PWR_DIRECT_SMPS_SUPPLY);
 
  /** Configure the main internal regulator output voltage
  */
  __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);
 
  while(!__HAL_PWR_GET_FLAG(PWR_FLAG_VOSRDY)) {}
 
  /** Configure LSE Drive Capability
  */
  //check if LSE was configured before
  if (HAL_RTCEx_BKUPRead(&hrtc, RTC_BKP_DR0) != RTC_BKUP_DEFINE_CODE)
  {
    HAL_PWR_EnableBkUpAccess();
    __HAL_RCC_LSEDRIVE_CONFIG(RCC_LSEDRIVE_LOW);
  }
  /** Macro to configure the PLL clock source
  */
  __HAL_RCC_PLL_PLLSOURCE_CONFIG(RCC_PLLSOURCE_HSE);
 
  /** Initializes the RCC Oscillators according to the specified parameters
  * in the RCC_OscInitTypeDef structure.
  */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI|RCC_OSCILLATORTYPE_HSE;
  RCC_OscInitStruct.HSEState = RCC_HSE_ON;
  RCC_OscInitStruct.HSIState = RCC_HSI_DIV1;
  RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
  RCC_OscInitStruct.PLL.PLLM = 5;
  RCC_OscInitStruct.PLL.PLLN = 160;
  RCC_OscInitStruct.PLL.PLLP = 2;
  RCC_OscInitStruct.PLL.PLLQ = 2;
  RCC_OscInitStruct.PLL.PLLR = 2;
  RCC_OscInitStruct.PLL.PLLRGE = RCC_PLL1VCIRANGE_2;
  RCC_OscInitStruct.PLL.PLLVCOSEL = RCC_PLL1VCOWIDE;
  RCC_OscInitStruct.PLL.PLLFRACN = 0;
 
  //check if LSE was configured before
  if (HAL_RTCEx_BKUPRead(&hrtc, RTC_BKP_DR0) != RTC_BKUP_DEFINE_CODE)
  {
    RCC_OscInitStruct.OscillatorType |= RCC_OSCILLATORTYPE_LSE;
    RCC_OscInitStruct.LSEState = RCC_LSE_ON;
  }
 
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }
 
  /** Initializes the CPU, AHB and APB buses clocks
  */
  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                              |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2
                              |RCC_CLOCKTYPE_D3PCLK1|RCC_CLOCKTYPE_D1PCLK1;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
  RCC_ClkInitStruct.SYSCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_HCLK_DIV2;
  RCC_ClkInitStruct.APB3CLKDivider = RCC_APB3_DIV2;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_APB1_DIV2;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_APB2_DIV2;
  RCC_ClkInitStruct.APB4CLKDivider = RCC_APB4_DIV2;
 
  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK)
  {
    Error_Handler();
  }
  HAL_RCC_MCOConfig(RCC_MCO1, RCC_MCO1SOURCE_HSI, RCC_MCODIV_1);
}
 
 
static void MX_RTC_Init(void)
{
  RTC_TimeTypeDef sTime = {0};
  RTC_DateTypeDef sDate = {0};
 
  /** Initialize RTC Only
  */
  hrtc.Instance = RTC;
  hrtc.Init.HourFormat = RTC_HOURFORMAT_24;
  hrtc.Init.AsynchPrediv = 127;
  hrtc.Init.SynchPrediv = 255;
  hrtc.Init.OutPut = RTC_OUTPUT_DISABLE;
  hrtc.Init.OutPutPolarity = RTC_OUTPUT_POLARITY_HIGH;
  hrtc.Init.OutPutType = RTC_OUTPUT_TYPE_OPENDRAIN;
  hrtc.Init.OutPutRemap = RTC_OUTPUT_REMAP_NONE;
  if (HAL_RTC_Init(&hrtc) != HAL_OK)
  {
    Error_Handler();
  }
 
  /* USER CODE BEGIN Check_RTC_BKUP */
 
  //Check if Data stored in BackUp register1: No Need to reconfigure RTC#
  if (HAL_RTCEx_BKUPRead(&hrtc, RTC_BKP_DR0) == RTC_BKUP_DEFINE_CODE)
  {
    // Only read time and date
    HAL_RTC_GetTime(&hrtc, &sTime, RTC_FORMAT_BCD);
    HAL_RTC_GetDate(&hrtc, &sDate, RTC_FORMAT_BCD);
  }
  else
  {
    // Write to BackUp register1 and initialize RTC and set the Time and Date
    HAL_RTCEx_BKUPWrite(&hrtc, RTC_BKP_DR0, RTC_BKUP_DEFINE_CODE);
 
  /* USER CODE END Check_RTC_BKUP */
 
  /** Initialize RTC and set the Time and Date
  */
    sTime.Hours = 0x0;
    sTime.Minutes = 0x0;
    sTime.Seconds = 0x0;
    sTime.DayLightSaving = RTC_DAYLIGHTSAVING_NONE;
    sTime.StoreOperation = RTC_STOREOPERATION_RESET;
    if (HAL_RTC_SetTime(&hrtc, &sTime, RTC_FORMAT_BCD) != HAL_OK)
    {
      Error_Handler();
    }
    sDate.WeekDay = RTC_WEEKDAY_MONDAY;
    sDate.Month = RTC_MONTH_JANUARY;
    sDate.Date = 0x1;
    sDate.Year = 0x0;
 
    if (HAL_RTC_SetDate(&hrtc, &sDate, RTC_FORMAT_BCD) != HAL_OK)
    {
      Error_Handler();
    }
  /* USER CODE BEGIN RTC_Init 2 */
  }
  /* USER CODE END RTC_Init 2 */
 
}

Thanks for any hints!

[AScha.3]

i had some (similar ?) problems with H7 chips, if core supply is not 0V at power/start . RTC always 3V batt.

so try : disconnect power, make short VCAP to GND, cross Cx (should be 2uF , C20) , to discharge 100% . then connect power ... should start.

[kens0o]

Thanks for the hint!

I don't know exactly why, but it works now.

I think the reason was the m4 core, which still had the demo running.

This also fixed problems with the ethernet connection.