CubeMX 6.17.0 generates wrong code for HSE_RTC divider

[Gunnar Bohlen]

Hi,

I'm using STM32H5F5LJHxQ. External HSE Oscillator is 48MHz. RTC clock mux is set to HSE_RTC, divider set to "/48" and the tool shows correctly that RTC clock is 1000kHz (48MHz / 48).

During my tests I discovered a wrong RTC time, error ~2%. (1.2 seconds deviation per minute)

In the generated function HAL_RTC_MspInit() is see: (49 instead of the expected 48)

PeriphClkInitStruct.RTCClockSelection = RCC_RTCCLKSOURCE_HSE_DIV49;	

If I change the configuration in CubeMX to create a divider of 47, the correct RCC_RTCCLKSOURCE_HSE_DIV47 is generated
If I change the configuration in CubeMX to create a divider of 49, the correct RCC_RTCCLKSOURCE_HSE_DIV49 is. generated.

If I manually set the correct RCC_RTCCLKSOURCE_HSE_DIV48 in the sources, the RTC runs correctly. 

Regards,

Gunnar Bohlen
HMS Networks

[mƎALLEm]

Hello,

Could you please share your ioc file so we could reproduce from our side?

[Gunnar Bohlen]

Hello,

find the ioc file attached.HSR_RTC divider is set to /48.

After code generation the file stm32h5xx_hal_msp.c contains the function

void HAL_RTC_MspInit(RTC_HandleTypeDef* hrtc)
{
  RCC_PeriphCLKInitTypeDef PeriphClkInitStruct = {0};
  if(hrtc->Instance==RTC)
  {
    /* USER CODE BEGIN RTC_MspInit 0 */

    /* USER CODE END RTC_MspInit 0 */

  /** Initializes the peripherals clock
  */
    PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_RTC;
    PeriphClkInitStruct.RTCClockSelection = RCC_RTCCLKSOURCE_HSE_DIV49;
    if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct) != HAL_OK)
    {
      Error_Handler();
    }

    /* Peripheral clock enable */
    __HAL_RCC_RTC_ENABLE();
    __HAL_RCC_RTCAPB_CLK_ENABLE();
    /* USER CODE BEGIN RTC_MspInit 1 */

    /* USER CODE END RTC_MspInit 1 */

  }

}

 with the clock set to RCC_RTCCLKSOURCE_HSE_DIV49 instead of 48.

[mƎALLEm]

Hello,

Thanks for the sharing. I've reproduced the behavior from my side.

I'll report that internally for analysis and eventual fix. Internal ticket for tracking CDM0062030 (not accessible by ST community users).