STM32 Nucleo H7A3ZI board UART Issue

Question

Hi Community,
I am facing very basic issue. My UART in H7A3ZI Nucleo 144 board is not displaying correctly on terminal. 
My UART Setting:

huart3.Instance = USART3;

huart3.Init.BaudRate = 115200;

huart3.Init.WordLength = UART_WORDLENGTH_8B;

huart3.Init.StopBits = UART_STOPBITS_1;

huart3.Init.Parity = UART_PARITY_NONE;

huart3.Init.Mode = UART_MODE_TX_RX;

huart3.Init.HwFlowCtl = UART_HWCONTROL_NONE;

huart3.Init.OverSampling = UART_OVERSAMPLING_16;

huart3.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;

huart3.Init.ClockPrescaler = UART_PRESCALER_DIV1;

huart3.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;

if (HAL_UART_Init(&huart3) != HAL_OK)

My Code:

int _write(int file, char *ptr, int len)

{

HAL_UART_Transmit(&huart3, (uint8_t*)ptr, len, HAL_MAX_DELAY);

return len;

}
//and

while (1)

{

/* USER CODE END WHILE */

/* USER CODE BEGIN 3 */

printf("current number is %d
", counter++);

HAL_Delay(500);

}
 
My Buad rate is 115200 
This is basic code to get UART output data on ST link virtual serial port that is connected to Laptop.

Andrew Neil · Accepted Answer

@mahmanish wrote:Can you please explain why it is so A fundamental requirement of asynchronous serial comms - ie, UART comms, as here - is that the sender and receiver must be working at the same baud rate.If the baud rates differ, the receiver will not be able to correctly recognise what was sent.For reliable comms, the baud rate error should not exceed about 2%.The above is all entirely general - not specific to ST or STM32. The sending baud rate on your STM32 is derived from the clock; so, if your clock is not what you think, then the baud rate will be wrong - and you will get corrupted comms:https://learn.sparkfun.com/tutorials/serial-communication/all#:~:text=If%20two%20devices%20aren%27t%20speaking%20at%20the%20same%20speed%2C%20data%20can%20be%20either%20misinterpreted%2C%20or%20completely%20missed. https://electronics.stackexchange.com/questions/7610/what-is-the-maximum-acceptable-baud-rate-error-for-rs-232-serial-communication  This is why I always suggest that people use an oscilloscope or logic analyser to look at the signal on the wire - and verify the actual baud rate. #BaudRateError #SerialGarbage #BaudRate

Tesla DeLorean · Answer

Watch what value HSE_VALUE is using, against the MCO frequency the ST-LINK/V3 is actually generating.

25 MHz / 3 = 8.333333 MHz, not 8.000 MHz

The firmware update tool should provide some clocking options.

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