How to use USART single wire(half-duplex) for SDI-12 communication protocol with STM32G081 using Stm32cubeIDE???

[Dprom]

Hi Genius,

I am using STM32G081T6 with STM32cubeIDE. I found out in pinout & configuration setting, there are several USART modes including Single Wire (half-duplex). I set baud rate to 1200, word length to 7Bits, parity even and 1 stop bit. Then connect the single pin with arduino maker nano who already tested with real SDI-12 sensor. I ping dummy msg from arduino to stm32 but doesn't get expected value. Guide me to solve this, there might be something that I missed

Thanks in advanced

[TDK]

The number of data bits includes parity, so you will need to set 8 bits if you have 7 data bits.

Single wire is nontrivial, as the two devices need to be in sync in order not to talk over each other. Show the code you're using.

[Peter BENSCH]

SDI-12 doesn't seem to be very common because this question rarely came up here.

Maybe a version on Github that can be found here will help you further?

Regards

/Peter

[Dprom]

int main(void)
{
  /* USER CODE BEGIN 1 */
	uint8_t UART1_rxBuffer[255] = {0};
 
  /* USER CODE END 1 */
 
  /* MCU Configuration--------------------------------------------------------*/
 
  /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
  HAL_Init();
 
  /* USER CODE BEGIN Init */
 
  /* USER CODE END Init */
 
  /* Configure the system clock */
  SystemClock_Config();
 
  /* USER CODE BEGIN SysInit */
 
  /* USER CODE END SysInit */
 
  /* Initialize all configured peripherals */
  MX_GPIO_Init();
  MX_USART1_UART_Init();
  MX_I2C1_Init();
  MX_SPI1_Init();
  MX_USART2_UART_Init();
  MX_USART3_UART_Init();
  MX_DMA_Init();
  MX_USART4_UART_Init();
  /* USER CODE BEGIN 2 */
 
  /* USER CODE END 2 */
 
  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  HAL_UART_Transmit(&huart1, (uint8_t*)"Write Something\r\n", 17, HAL_MAX_DELAY);
 
  while (1)
  {
	  //HAL_UART_Receive(&huart1, &UART1_rxBuffer[0], 12, 500);
	  HAL_UART_Receive(&huart2, &UART1_rxBuffer[0], 12, 500);
	  HAL_UART_Transmit(&huart1, UART1_rxBuffer, strlen((char*)UART1_rxBuffer), HAL_MAX_DELAY);
	  UART1_rxBuffer[0] = 0;
    /* USER CODE END WHILE */
 
    /* USER CODE BEGIN 3 */
  }
  /* USER CODE END 3 */
}
static void MX_USART1_UART_Init(void)
{
 
  /* USER CODE BEGIN USART1_Init 0 */
 
  /* USER CODE END USART1_Init 0 */
 
  /* USER CODE BEGIN USART1_Init 1 */
 
  /* USER CODE END USART1_Init 1 */
  huart1.Instance = USART1;
  huart1.Init.BaudRate = 1200;
  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();
  }
  /* USER CODE BEGIN USART1_Init 2 */
 
  /* USER CODE END USART1_Init 2 */
 
}
 
static void MX_USART2_UART_Init(void)
{
 
  /* USER CODE BEGIN USART2_Init 0 */
 
  /* USER CODE END USART2_Init 0 */
 
  /* USER CODE BEGIN USART2_Init 1 */
 
  /* USER CODE END USART2_Init 1 */
  huart2.Instance = USART2;
  huart2.Init.BaudRate = 1200;
  huart2.Init.WordLength = UART_WORDLENGTH_7B;
  huart2.Init.StopBits = UART_STOPBITS_1;
  huart2.Init.Parity = UART_PARITY_EVEN;
  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_ENABLE;
  huart2.Init.ClockPrescaler = UART_PRESCALER_DIV1;
  huart2.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;
  if (HAL_HalfDuplex_Init(&huart2) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_UARTEx_SetTxFifoThreshold(&huart2, UART_TXFIFO_THRESHOLD_1_8) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_UARTEx_SetRxFifoThreshold(&huart2, UART_RXFIFO_THRESHOLD_1_8) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_UARTEx_DisableFifoMode(&huart2) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN USART2_Init 2 */
 
  /* USER CODE END USART2_Init 2 */
 
}

Hi master,

This is my codes. Arduino always ping "0I!" every 1 sec.

  while(1)
  {
    String command = "";
    command += "0";
    command += "I!";
    Serial.println("Send: " + command);
    mySDI12.sendCommand(command);
    delay(1000);
  }

[Dprom]

Hi master,

Thanks for you suggestion. Share with me if there are new update added for SDI-12 example using STMcubeIDE

Regards

[TDK]

> 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;

> huart2.Init.WordLength = UART_WORDLENGTH_7B;

> huart2.Init.StopBits = UART_STOPBITS_1;

> huart2.Init.Parity = UART_PARITY_EVEN

> huart2.Init.Mode = UART_MODE_TX_RX;

The code you posted uses two UARTs, neither of which is in single wire mode. One has 8 data bits and no parity, the other has 6 data bits plus one even parity. Hard to know what the intention is here.

[Dprom]

.

[Dprom]

.

[Dprom]

uart 1 for debug, uart 2 for SDI-12 sir.. means uart 2 is for single wire. It shows in the init function as below.

  if (HAL_HalfDuplex_Init(&huart2) != HAL_OK)
  {
    Error_Handler();
  }

Regards

[TDK]

You're right. The word length is still incorrect, however.