After restart device UART_3 printing some rubbish ţ˙ţţţţţţţţüţüüüüüüüüüüüüüüüüüü

[KWiśn.2]

Dear,

Microcontroler STM32H742 (stm32CubeIDE)

When i plug out and plug in device, this printing on UART_3:

ţ˙ţţţţţţţţüţüüüüüüüüüüüüüüüüüü

or:

ţ

NVT: FF FE FE

ţţ{FF}

i this problem was not watched on same device with stm32F205(Rowley crossworks).

I clear all buffer 

char bufRcv[256] {'\0'}; but it nothing change

Could you have some solution

Many thanks

[waclawek.jan]

> I mean Plug the power cord to the mains.

> I have RS232 on mainboard in computer and i use db9 cable.

> problem is only after Plug the power cord to the mains.

Don't transmit anything in the STM32 software, just unplug and plug. Still receiving strange characters? Then you a hardware-related problem: observe the line using oscilloscope during unplugging/plugging in. What exactly happens during power-up depends on how exactly the power source and the interface circuitry is designed.

JW

[LCE]

Okay, we're getting closer...

Still missing:

• DMA init
• the "linking" function between hardware UART and printf

[KWiśn.2]

Sorry for the delay, I was sick.

//--------------------------------------------------------------------------------------

void UART_3::Init()

{

 __HAL_RCC_DMA1_CLK_ENABLE();

 HAL_NVIC_SetPriority(DMA1_Stream3_IRQn, 3, 0);

 HAL_NVIC_EnableIRQ(DMA1_Stream3_IRQn);

 /* Peripheral interrupt init */

 HAL_NVIC_SetPriority(USART3_IRQn, 2, 0);

 HAL_NVIC_EnableIRQ(USART3_IRQn);

 __HAL_UART_ENABLE_IT(&huart3,UART_IT_RXNE);

}

//--------------------------------------------------------------------------------------

void UART_3::ParametersChanged()

{

 ConfigureUsart();

}

//--------------------------------------------------------------------------------------

void UART_3::ConfigureUsart()

{

 uint16_t parity = DecodeParity(Params.Com1_Parity);

 huart3.Instance = USART3;

 huart3.Init.BaudRate = DecodeBaudrate(Params.Com1_Baudrate);

 huart3.Init.WordLength = (parity == PARITY_NONE) ? UART_WORDLENGTH_8B : UART_WORDLENGTH_9B;

 huart3.Init.StopBits = UART_STOPBITS_1;

 huart3.Init.Parity = parity;

 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) Error_Handler();

 if (HAL_UARTEx_SetTxFifoThreshold(&huart3, UART_TXFIFO_THRESHOLD_1_8) != HAL_OK) Error_Handler();

 if (HAL_UARTEx_SetRxFifoThreshold(&huart3, UART_RXFIFO_THRESHOLD_1_8) != HAL_OK) Error_Handler();

 if (HAL_UARTEx_DisableFifoMode(&huart3) != HAL_OK) Error_Handler();

}

//--------------------------------------------------------------------------------------

[KWiśn.2]

//--------------------------------------------------------------------------------------
extern "C" void USART3_IRQHandler(void)
{
	if (__HAL_UART_GET_FLAG(&huart3, UART_FLAG_ORE))
	{
		__HAL_UART_CLEAR_FLAG(&huart3, UART_CLEAR_OREF);
	}
 if(__HAL_UART_GET_IT_SOURCE(&huart3,UART_IT_RXNE) != RESET && __HAL_UART_GET_FLAG(&huart3, UART_FLAG_RXNE) != RESET )
 {
		 char data = huart3.Instance->RDR & (uint8_t)0x00FF;
		 Com1.ByteReceivedIsr(data);
}
	HAL_DMA_IRQHandler(&hdma_usart3_tx);
}
 

[KWiśn.2]

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

{

int DataIdx;

for (DataIdx = 0; DataIdx < len; DataIdx++)

{

__io_putchar(*ptr++);

}

return len;

}

[LCE]

There is still no link to the UART whatsoever.

So the _write function needs some output to the UART, like you give the pointer and length to the UART DMA transmit function.

[KWiśn.2]

Uart still work, this problem is only when plug the power cord to the mains, after start all transmition work correctly.

[ONadr.1]

Try to disable bootloader. This is the first FW which can use UART.

[KWiśn.2]

You're right, i forget