STM32 串口转 虚拟串口---实现USB转串口功能

一，USART与UART 区别

USART（Universal Synchronous/Asynchronous Receiver/Transmitter）通用同步/异步串行接收/发送器

相较于UART：通用异步收发传输器（Universal Asynchronous Receiver/Transmitter）多了一个S，即synchronous（同步）。

也就是说UART相较于USART只是少了一个同步方式而已，而串口在嵌入式中经常使用，但是我们一般使用UART就够

这些操作可以在Cubemx下自动生成。

二，串口初始化

void MX_USART1_Init(void)
{

  husart1.Instance = USART1;
  husart1.Init.BaudRate = 115200;
  husart1.Init.WordLength = USART_WORDLENGTH_8B;
  husart1.Init.StopBits = USART_STOPBITS_1;
  husart1.Init.Parity = USART_PARITY_NONE;
  husart1.Init.Mode = USART_MODE_TX_RX;
  husart1.Init.HwFlowCtl = UART_HWCONTROL_NONE;
  husart1.Init.OverSampling = UART_OVERSAMPLING_16;
  husart1.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
  husart1.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;
  if (HAL_UART_Init(&husart1) != HAL_OK)
  {
    Error_Handler();
  }
    
    //HAL_UART_Receive_IT(&husart1, (u8 *)aRxBuffer, RXBUFFERSIZE);//该函数会开启接收中断：标志位UART_IT_RXNE，并且设置接收缓冲以及接收缓冲接收最大数据量
    
    //HAL_UARTEx_ReceiveToIdle_IT(&husart1, (u8 *)aRxBuffer, RXBUFFERSIZE);//串口接收任意字长字符串
}

三。IO初始化，DMA通道的设置

void HAL_UART_MspInit(UART_HandleTypeDef* usartHandle)
{GPIO_InitTypeDef GPIO_InitStruct = {0};if(usartHandle->Instance==USART1){/* USER CODE BEGIN USART1_MspInit 0 *//* USER CODE END USART1_MspInit 0 *//* USART1 clock enable */__HAL_RCC_USART1_CLK_ENABLE();__HAL_RCC_GPIOA_CLK_ENABLE();GPIO_InitStruct.Pin = GPIO_PIN_9|GPIO_PIN_10;GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;GPIO_InitStruct.Pull = GPIO_NOPULL;GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;GPIO_InitStruct.Alternate = GPIO_AF7_USART1;HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);/* USART1 DMA Init *//* USART1_RX Init */hdma_usart1_rx.Instance = DMA1_Channel5;hdma_usart1_rx.Init.Direction = DMA_PERIPH_TO_MEMORY;hdma_usart1_rx.Init.PeriphInc = DMA_PINC_DISABLE;hdma_usart1_rx.Init.MemInc = DMA_MINC_ENABLE;hdma_usart1_rx.Init.PeriphDataAlignment = DMA_PDATAALIGN_BYTE;hdma_usart1_rx.Init.MemDataAlignment = DMA_MDATAALIGN_BYTE;hdma_usart1_rx.Init.Mode = DMA_NORMAL;hdma_usart1_rx.Init.Priority = DMA_PRIORITY_HIGH;if (HAL_DMA_Init(&hdma_usart1_rx) != HAL_OK){Error_Handler();}__HAL_LINKDMA(usartHandle,hdmarx,hdma_usart1_rx);/* USART1_TX Init */hdma_usart1_tx.Instance = DMA1_Channel4;hdma_usart1_tx.Init.Direction = DMA_MEMORY_TO_PERIPH;hdma_usart1_tx.Init.PeriphInc = DMA_PINC_DISABLE;hdma_usart1_tx.Init.MemInc = DMA_MINC_ENABLE;hdma_usart1_tx.Init.PeriphDataAlignment = DMA_PDATAALIGN_BYTE;hdma_usart1_tx.Init.MemDataAlignment = DMA_MDATAALIGN_BYTE;hdma_usart1_tx.Init.Mode = DMA_NORMAL;hdma_usart1_tx.Init.Priority = DMA_PRIORITY_LOW;if (HAL_DMA_Init(&hdma_usart1_tx) != HAL_OK){Error_Handler();}__HAL_LINKDMA(usartHandle,hdmatx,hdma_usart1_tx);#if EN_USART1_RX/* USART1 interrupt Init */HAL_NVIC_SetPriority(USART1_IRQn, 1,1);HAL_NVIC_EnableIRQ(USART1_IRQn);
#endif	}
}

四。DMA 中断的设置，注意，如果USART或DMA的中断优先级被设置得太低，它们可能会被其他高优先级的中断延迟。

void MX_DMA_Init(void)
{

  /* DMA controller clock enable */
  __HAL_RCC_DMA1_CLK_ENABLE();

  /* DMA interrupt init */
  /* DMA1_Channel4_IRQn interrupt configuration */
  HAL_NVIC_SetPriority(DMA1_Channel4_IRQn, 1, 0);
  HAL_NVIC_EnableIRQ(DMA1_Channel4_IRQn);
  /* DMA1_Channel5_IRQn interrupt configuration */
  HAL_NVIC_SetPriority(DMA1_Channel5_IRQn, 0, 0);
  HAL_NVIC_EnableIRQ(DMA1_Channel5_IRQn);

}

 五，DMA中断服务函数 不定长接收

停止HAL_UART_DMAStop(&husart1);  

  dat_len =  sizeof(aRxBuffer) - __HAL_DMA_GET_COUNTER(&hdma_usart1_rx);     //计算接收到的数据长度
        
        USB_USART_Send(aRxBuffer,dat_len);//虚拟串口转发    
        dat_len = 0;//清零
         memset(aRxBuffer,0,sizeof(aRxBuffer)); //重置
        Error_code_uart1=HAL_UARTEx_ReceiveToIdle_DMA(&husart1, (u8 *)aRxBuffer, sizeof(aRxBuffer));//再次开启DMA

void HAL_UARTEx_RxEventCallback(UART_HandleTypeDef *huart, uint16_t Size) 
{if(huart->Instance==USART1)//如果是串口1{HAL_UART_DMAStop(&husart1);  dat_len =  sizeof(aRxBuffer) - __HAL_DMA_GET_COUNTER(&hdma_usart1_rx);     //计算接收到的数据长度USB_USART_Send(aRxBuffer,dat_len);//虚拟串口转发    dat_len = 0;memset(aRxBuffer,0,sizeof(aRxBuffer)); Error_code_uart1=HAL_UARTEx_ReceiveToIdle_DMA(&husart1, (u8 *)aRxBuffer, sizeof(aRxBuffer));}}
//串口1中断服务程序
void USART1_IRQHandler(void)                    
{     HAL_UART_IRQHandler(&husart1);    //调用HAL库中断处理公用函数    
} 
void DMA1_Channel4_IRQHandler(void)
{HAL_DMA_IRQHandler(&hdma_usart1_tx);
}/*** @brief This function handles DMA1 channel5 global interrupt.*/
void DMA1_Channel5_IRQHandler(void)
{HAL_DMA_IRQHandler(&hdma_usart1_rx);
}

六，初始化 及溢出错误处理

if (Error_code_uart1 != HAL_OK)//出错，重开
    {
        // 清空缓冲，置位一些标志，具体看函数内部
        HAL_UART_AbortReceive(&husart1);
        // 重启接收
        Error_code_uart1=HAL_UARTEx_ReceiveToIdle_DMA(&husart1, (u8 *)aRxBuffer, sizeof(aRxBuffer));
        }

int main(void)
{  u8 len;	/* Reset of all peripherals, Initializes the Flash interface and the Systick. */HAL_Init(); /* Configure the system clock */SystemClock_Config();/* Initialize all configured peripherals */MX_GPIO_Init();USB_Reset();       // USB断开再重连HAL_Delay(1);MX_USB_DEVICE_Init();MX_DMA_Init();MX_USART1_Init();HAL_Delay(2000);//等待虚拟串口初始化完成Error_code_uart1=HAL_UARTEx_ReceiveToIdle_DMA(&husart1, (u8 *)aRxBuffer, sizeof(aRxBuffer));while (1){u8 usbstatus = 0;if (usbstatus != USB_GetStatus()){usbstatus = USB_GetStatus(); // 记录新的状态}if (Error_code_uart1 != HAL_OK)//出错，重开{// 清空缓冲，置位一些标志，具体看函数内部HAL_UART_AbortReceive(&husart1);// 重启接收Error_code_uart1=HAL_UARTEx_ReceiveToIdle_DMA(&husart1, (u8 *)aRxBuffer, sizeof(aRxBuffer));}}}