Simple UART problem STM32H753

[GlennH]

Hi,
I'm relatively new to the STM32 world and I'm becoming frustrated that I can't make a simple UART work. No DMA, no interrupts just trying to send bytes out of the UART and then receive them. Here is my setup code:

void UART7_Init(void)
{

	GPIO_InitTypeDef GPIO_InitStruct;

		HAL_Init();


	    /* Peripheral clock enable */
    __HAL_RCC_UART7_CLK_ENABLE();
    __HAL_RCC_GPIOF_CLK_ENABLE();

    /**UART7 GPIO Configuration
    PF6     ------> UART7_RX
    PF7     ------> UART7_TX
    PF8     ------> UART7_RTS
    PF9     ------> UART7_CTS
    */
    GPIO_InitStruct.Pin = U7_PAY_RX_SPI5_NSS_Pin|U7_PAY_TX_SPI5_SCK_Pin;
    GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
    GPIO_InitStruct.Pull = GPIO_NOPULL;
    GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
    GPIO_InitStruct.Alternate = GPIO_AF7_UART7;
    HAL_GPIO_Init(GPIOF, &GPIO_InitStruct);


    huart7.Instance = UART7;
    huart7.Init.BaudRate = 115200;
    huart7.Init.WordLength = UART_WORDLENGTH_8B;
    huart7.Init.StopBits = UART_STOPBITS_1;
    huart7.Init.Parity = UART_PARITY_NONE;
    huart7.Init.Mode = UART_MODE_TX_RX;
    huart7.Init.HwFlowCtl = UART_HWCONTROL_NONE;
    huart7.Init.OverSampling = UART_OVERSAMPLING_16;
    huart7.Init.OneBitSampling = UART_ONEBIT_SAMPLING_DISABLED;
    huart7.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;

    	if(HAL_UART_Init(&huart7) != HAL_OK)
    	{
    		asm("bkpt 255"); // Just for degugging
    		Error_Handler();
    	}

    /* UART7 interrupt Init */
    //HAL_NVIC_SetPriority(UART7_IRQn, 5, 0);
    //HAL_NVIC_EnableIRQ(UART7_IRQn);
  /* USER CODE BEGIN UART7_MspInit 1 */

  /* USER CODE END UART7_MspInit 1 */
  }

And here is the actual transmit code:

do
	{
	drv_led_toggle(DRV_LED_ID_AMBER);
	HAL_UART_Transmit(&huart7, receiveBuffer, sizeof(receiveBuffer), TIMEOUT);
	HAL_Delay(300);
	//HAL_UART_Receive(&huart7, receiveBuffer, 1, TIMEOUT);
	drv_led_toggle(DRV_LED_ID_AMBER);
	HAL_Delay(300);

	if(UART7->ISR & (1<<5))
	    {
		HAL_UART_Receive(&huart7, receiveBuffer  , 1 /*sizeof(receiveBuffer)*/, TIMEOUT);
	    }

	if(i%2)drv_led_toggle(DRV_LED_ID_AMBER);


	} while(i<5);

I'm pretty sure that it's something simple and I'm just missing it. Any advice is appreciated.

Thanks.

[Andrew Neil]

How are you attempting to observe the transmitted bytes?

Is this on an ST board?

• If yes, which one?
• If not, please provide schematics.

[SofLit]

Hello,

just trying to send bytes out of the UART and then receive them. Here is my setup code:

---

Send receive to which device? a PC HyperTerminal or what? or looping back Tx/Rx?

Need to give more details ..

[Tesla DeLorean]

Send a readable string first, check on terminal.

For receive need to make sure any kind of receive error is cleared, ie noise, framing, parity, etc

PF6/PF7 AF7 for UART7 seem correct

Polled method are inherently half-duplex, there aren't deep buffers, not going to capture standing waves from signals transmitted 300 ms earlier. Even if TX/RX looped back.

Transmit a continuous 0x55 'U' pattern, confirm baud / bit timing with a scope.

[GlennH]

I'm observing the output on an Analog discovery pro as a Logic analyzer. I have also hooked up a basic USB to serial TX pin on another channel as a sanity check that it is working.

It is not on an ST eval board it is on a proprietary CubeSat "On Board Computer".

Thanks!

[GlennH]

Currently, I'm observing the TX pin on a logic analyzer. Just want to see it actually transmit something right now.

Thanks.

[Tesla DeLorean]

Send known patterns. 0x55 would be good for checking baud rates at 8N1

[Peter BENSCH]

Uhm… CubeSat On Board Computer is based on Microchip PIC32MZ M14K. Do you realise that this is the community of STMicroelectronics?

Regards
/Peter

[SofLit]

So start by debugging the transmission.

As stated by @Tesla DeLorean send patterns 0x55 or 0xAA to at least be sure that you have a signal at Tx pin and you have the right bitrate.

In your first comment you said:

"just trying to send bytes out of the UART and then receive them"

I asked you how are you doing that? looping back Tx/Rx or send doing a communication with another device?.

Because in the second case you need to have the exact UART configuration at both sides: baudrate, parity, data length etc .. In the first case it's simple as it's the same config for the same UART. You can start by looping back Tx/Rx of UART7 by sending/receiving one byte ..

You can start by inspiring from that example: https://github.com/STMicroelectronics/STM32CubeH7/blob/master/Projects/STM32H743I-EVAL/Examples/UART/UART_Printf/Src/main.c

[GlennH]

This is not That CubeSat OBC. This is based on the STM32H753II