Upgraded my project to a new MCU, going from 80MHz to 120MHz SysClock. Since then my USART1 and 2 do not work well. My debugging until now suggests a baud rate problem. Where (which file) can I modify the prescaler/divisor if needed?

[Tesla DeLorean]

Try using Grep or Find-In-Files? USART_PRESC_PRESCALER

I used this type of thing on an L4R5ZI, needed a prescaler to hit lower bauds. Might also check the clock sources and stability.

void InitUART(void)
{
  UART_HandleTypeDef UartHandle = {0};
 
  __USART1_CLK_ENABLE();
...
 
  /*## Configure the UART peripheral ######################################*/
  /* Put the USART peripheral in the Asynchronous mode (UART Mode) */
  /* UART1 configured as follow:
      - Word Length = 8 Bits
      - Stop Bit = One Stop bit
      - Parity = NO parity
      - BaudRate = 115200 baud
      - Hardware flow control disabled (RTS and CTS signals) */
  UartHandle.Instance        = USART1;
 
  UartHandle.Init.BaudRate   = 115200;
  UartHandle.Init.WordLength = UART_WORDLENGTH_8B;
  UartHandle.Init.StopBits   = UART_STOPBITS_1;
  UartHandle.Init.Parity     = UART_PARITY_NONE;
  UartHandle.Init.HwFlowCtl  = UART_HWCONTROL_NONE;
  UartHandle.Init.Mode       = UART_MODE_TX_RX;
 
  UartHandle.Init.OverSampling   = UART_OVERSAMPLING_16;
#ifdef UART_ONE_BIT_SAMPLE_DISABLE
  UartHandle.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
#endif
#ifdef USART_PRESC_PRESCALER
  UartHandle.Init.ClockPrescaler = UART_PRESCALER_DIV4; //1,2,4,6,8,10,12,16,32,64,128,256
#endif
 
  if (HAL_UART_Init(&UartHandle) != HAL_OK)
  {
    /* Initialization Error */
    Error_Handler(__FILE__, __LINE__);
  }
}

[TDK]

Initializations are in main.c by default in MX_*_Init functions.

Also check that the clock source is correct. If using HSI, ensure trim value is as expected.

[VNado.1]

I do use HSI. How do I setup the trim value?

Which value do I set up for the USART prescaler? How is it calculated?

This is what I have in the main.c

void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
  RCC_PeriphCLKInitTypeDef PeriphClkInit = {0};
 
  /** Configure the main internal regulator output voltage
  */
  if (HAL_PWREx_ControlVoltageScaling(PWR_REGULATOR_VOLTAGE_SCALE1_BOOST) != HAL_OK)
  {
    Error_Handler();
  }
  /** Initializes the CPU, AHB and APB busses clocks
  */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.HSICalibrationValue = 16;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;
  RCC_OscInitStruct.PLL.PLLM = 2;
  RCC_OscInitStruct.PLL.PLLN = 30;
  RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV7;
  RCC_OscInitStruct.PLL.PLLQ = RCC_PLLQ_DIV2;
  RCC_OscInitStruct.PLL.PLLR = RCC_PLLR_DIV2;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }
  /** Initializes the CPU, AHB and APB busses clocks
  */
  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                              |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
 
  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_5) != HAL_OK)
  {
    Error_Handler();
  }
 
  PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_USART1|RCC_PERIPHCLK_USART2
                              |RCC_PERIPHCLK_SAI1|RCC_PERIPHCLK_RNG|RCC_PERIPHCLK_ADC;
  PeriphClkInit.Usart1ClockSelection = RCC_USART1CLKSOURCE_PCLK2;
  PeriphClkInit.Usart2ClockSelection = RCC_USART2CLKSOURCE_PCLK1;
  PeriphClkInit.Sai1ClockSelection = RCC_SAI1CLKSOURCE_PIN;
  PeriphClkInit.RngClockSelection = RCC_RNGCLKSOURCE_PLLSAI1;
  PeriphClkInit.AdcClockSelection = RCC_ADCCLKSOURCE_SYSCLK;
  PeriphClkInit.PLLSAI1.PLLSAI1Source = RCC_PLLSOURCE_HSI;
  PeriphClkInit.PLLSAI1.PLLSAI1M = 2;
  PeriphClkInit.PLLSAI1.PLLSAI1N = 12;
  PeriphClkInit.PLLSAI1.PLLSAI1P = RCC_PLLP_DIV7;
  PeriphClkInit.PLLSAI1.PLLSAI1Q = RCC_PLLQ_DIV2;
  PeriphClkInit.PLLSAI1.PLLSAI1R = RCC_PLLR_DIV2;
  PeriphClkInit.PLLSAI1.PLLSAI1ClockOut = RCC_PLLSAI1_48M2CLK;
  if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK)
  {
    Error_Handler();
  }
 
  /**Configure the Systick interrupt time
      */
    HAL_SYSTICK_Config(HAL_RCC_GetHCLKFreq()/1000);
 
      /**Configure the Systick
      */
    HAL_SYSTICK_CLKSourceConfig(SYSTICK_CLKSOURCE_HCLK);
       /* SysTick_IRQn interrupt configuration */
    HAL_NVIC_SetPriority(SysTick_IRQn, 0, 0);
 
}

And this is what I have in the usart.c

void MX_USART1_UART_Init(unsigned int baudrate)
{
 
  huart1.Instance = USART1;
  huart1.Init.BaudRate = baudrate;
  huart1.Init.WordLength = UART_WORDLENGTH_8B;
  huart1.Init.StopBits = UART_STOPBITS_1;
  huart1.Init.Parity = UART_PARITY_NONE;
  huart1.Init.Mode = UART_MODE_TX_RX;
  huart1.Init.HwFlowCtl = UART_HWCONTROL_NONE;
  huart1.Init.OverSampling = UART_OVERSAMPLING_16;
  huart1.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
  //huart1.Init.ClockPrescaler = UART_PRESCALER_DIV1;
  huart1.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;
  if (HAL_UART_Init(&huart1) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_UARTEx_SetTxFifoThreshold(&huart1, UART_TXFIFO_THRESHOLD_1_8) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_UARTEx_SetRxFifoThreshold(&huart1, UART_RXFIFO_THRESHOLD_1_8) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_UARTEx_DisableFifoMode(&huart1) != HAL_OK)
  {
    Error_Handler();
  }
 
}
 
/* USART2 init function */
 
void MX_USART2_UART_Init(void)
{
 
  huart2.Instance = USART2;
  huart2.Init.BaudRate = 115200;
  huart2.Init.WordLength = UART_WORDLENGTH_8B;
  huart2.Init.StopBits = UART_STOPBITS_1;
  huart2.Init.Parity = UART_PARITY_NONE;
  huart2.Init.Mode = UART_MODE_TX_RX;
  huart2.Init.HwFlowCtl = UART_HWCONTROL_NONE;
  huart2.Init.OverSampling = UART_OVERSAMPLING_16;
  huart2.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
  huart2.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;
  if (HAL_UART_Init(&huart2) != HAL_OK)
  {
    Error_Handler();
  }
 
}

[VNado.1]

I have tried setting UART_PRESCALER_DIV64 according to what I calculated 120MHz/ (16 * 115200 Baud). That did change the characters, but still not the correct rate.

I have tried DIV32 and DIV128 without further success.

[VNado.1]

This is the clock config I have in CubeMX