STM32：使用RS485和多摩川编码器通信

本文主要讲使用STM32F767和绝对式多摩川TS5700N8501编码器通信的流程和注意事项。

TS5700N8501编码器推荐收发电路如下：

 首先使用STM32CubeMX生成RS485驱动部分功能代码，注意该款编码器的波特率是2.5Mbps。

 

注意使能的GPIO可以使用其他管脚，我们的主控板使用的是PA8。前期可以这么配置。

 配置时钟，这里配置的是48MHz。

 接下来，生成对应的项目工程，MDK-ARM就是生成对应的Keil工程。 

 接下来是接线：注意编码器正确接4根线即可。黑色接地，红色接5V电源。编码器的SD是蓝色，对应接的是控制板上面的管脚。编码器的是蓝黑色，对应接的是控制板上面的SD管脚。

注意编码器要保证5V供电，并且编码器的线比较细要注意保证连接可靠。 测试中遇到供电电压达不到5V，以及黑色接地线接触不好的情况，都会导致无法正常通信。

void MX_UART4_Init(void)
{

  /* USER CODE BEGIN UART4_Init 0 */

  /* USER CODE END UART4_Init 0 */

  /* USER CODE BEGIN UART4_Init 1 */

  /* USER CODE END UART4_Init 1 */
  huart4.Instance = UART4;
  huart4.Init.BaudRate = 2500000;
  huart4.Init.WordLength = UART_WORDLENGTH_8B;
  huart4.Init.StopBits = UART_STOPBITS_1;
  huart4.Init.Parity = UART_PARITY_NONE;
  huart4.Init.Mode = UART_MODE_TX_RX;
  huart4.Init.HwFlowCtl = UART_HWCONTROL_NONE;
  huart4.Init.OverSampling = UART_OVERSAMPLING_16;
  huart4.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
  huart4.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;
  if (HAL_RS485Ex_Init(&huart4, UART_DE_POLARITY_HIGH, 0, 0) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN UART4_Init 2 */

//  HAL_UART_Receive_IT(&huart4, rs485RxData, 1);
  /* USER CODE END UART4_Init 2 */

}

void HAL_UART_MspInit(UART_HandleTypeDef* uartHandle)
{

  GPIO_InitTypeDef GPIO_InitStruct = {0};
  RCC_PeriphCLKInitTypeDef PeriphClkInitStruct = {0};
  if(uartHandle->Instance==UART4)
  {
  /* USER CODE BEGIN UART4_MspInit 0 */

  /* USER CODE END UART4_MspInit 0 */
  /** Initializes the peripherals clock
  */
    PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_UART4;
    PeriphClkInitStruct.Uart4ClockSelection = RCC_UART4CLKSOURCE_PCLK1;
    if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct) != HAL_OK)
    {
      Error_Handler();
    }

    /* UART4 clock enable */
    __HAL_RCC_UART4_CLK_ENABLE();

    __HAL_RCC_GPIOA_CLK_ENABLE();
    __HAL_RCC_GPIOB_CLK_ENABLE();
    /**UART4 GPIO Configuration
    PA0/WKUP     ------> UART4_TX
    PA1     ------> UART4_RX
    PA8     ------> UART4_DE
    */
    GPIO_InitStruct.Pin = GPIO_PIN_0|GPIO_PIN_1;
    GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
    GPIO_InitStruct.Pull = GPIO_NOPULL;
    GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
    GPIO_InitStruct.Alternate = GPIO_AF8_UART4;
    HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

    GPIO_InitStruct.Pin = GPIO_PIN_8;
    GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
    GPIO_InitStruct.Pull = GPIO_PULLUP;
    GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
    GPIO_InitStruct.Alternate = GPIO_AF8_UART4;
    HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

    /* UART4 DMA Init */
    /* UART4_RX Init */
    hdma_uart4_rx.Instance = DMA1_Stream2;
    hdma_uart4_rx.Init.Channel = DMA_CHANNEL_4;
    hdma_uart4_rx.Init.Direction = DMA_PERIPH_TO_MEMORY;
    hdma_uart4_rx.Init.PeriphInc = DMA_PINC_DISABLE;
    hdma_uart4_rx.Init.MemInc = DMA_MINC_ENABLE;
    hdma_uart4_rx.Init.PeriphDataAlignment = DMA_PDATAALIGN_BYTE;
    hdma_uart4_rx.Init.MemDataAlignment = DMA_MDATAALIGN_BYTE;
    hdma_uart4_rx.Init.Mode = DMA_NORMAL;
    hdma_uart4_rx.Init.Priority = DMA_PRIORITY_LOW;
    hdma_uart4_rx.Init.FIFOMode = DMA_FIFOMODE_DISABLE;
    if (HAL_DMA_Init(&hdma_uart4_rx) != HAL_OK)
    {
      Error_Handler();
    }

    __HAL_LINKDMA(uartHandle,hdmarx,hdma_uart4_rx);

    /* UART4 interrupt Init */
    HAL_NVIC_SetPriority(UART4_IRQn, 0, 0);
    HAL_NVIC_EnableIRQ(UART4_IRQn);
  /* USER CODE BEGIN UART4_MspInit 1 */

  /* USER CODE END UART4_MspInit 1 */
  }
}

测试程序： 

void RS485_SendData(uint8_t *data, uint16_t size)
{
    HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_SET);
	HAL_UART_Transmit(&huart4, data, size, 1000);
    HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_RESET);
}

void RS485_RecvData(uint8_t *data, uint16_t size)
{
	HAL_UART_Receive(&huart4, data, size, 1000);
}

void RS485_Test(void)
{
    uint8_t Sendbuf[1] = {0x02};
    uint8_t Recvbuf[10] = {0x00};

    RS485_SendData(Sendbuf, sizeof(Sendbuf));

    RS485_RecvData(Recvbuf, 6);

    for(int i = 0; i < 6; i++)
    {
        Usart_Printf("%02x", Recvbuf[i]);
    }

    Usart_Printf("\n\r");
}

测试程序运行结果：