串口工具"/>
STM32实现USB转TTL串口工具
STM32实现USB转TTL串口工具
具有USB接口和UART接口的STM32芯片，如STM32F1, STM32F4等等，都可以实现USB转TTL串口工具的制作。目前具有USB接口的最小资源的芯片是STM32F103C6T6。这里介绍USB转UART的代码设计。
STM32例化的USB VCOM，数据通讯到STM32内部设定的缓存空间，如果不向外部进行UART转发，则VCOM的波特率为名义上的波特率，实际上是按照USB接口自动协商的差分速率在进行数据传输。在向外部进行UART转发时，UART的波特率可以单独配置，并不需要和VCOM端配置的名义上的波特率相同。而在向外部进行UART转发，且UART的波特率与VCOM的波特率一致时，也就实现了USB转TTL串口工具，设计的要点一是将USB传递的VCOM波特率信息，用于配置转发的UART的波特率；二是通过终端，DMA和缓存方式的配合，实现有效的时序转发。
如下介绍基本的USB转TTL串口转发逻辑设计，一些高级串口控制功能可以根据需要增加调整。
STM32工程配置
首先建立基本工程并配置时钟：
配置USB VCOM:
配置UART1作为转发串口：
保存并生成初始工程代码：
STM32工程代码
首先在usbd_cdc_if.c修改代码获取VCOM配置信息（事件自动触发）并重新配置转发串口UART1的波特率：
在重新配置转发串口UART1的波特率后，修改识别标识，main.c主程序里识别后开启UART1的单字节中断接收，并采用缓存方式解决通过USB VCOM转发未完成而UART1继续接收到数据的情况。当主程序里识别到UART1缓存区域有数据，则转存后通过USB VCOM发送出去，并修改UART1接收缓存区接收索引位置。
USB VCOM收到的数据，通过UART1的发送DMA方式发送出去。并且通过UART1的发送完成中断进行标识设置，代码通过缓存方式解决USB VCOM收到新的数据而UART1的数据发送未完成的情况。
usbd_cdc_if.c修改后的完整实现代码：
/* USER CODE BEGIN Header */
/********************************************************************************* @file : usbd_cdc_if.c* @version : v2.0_Cube* @brief : Usb device for Virtual Com Port.******************************************************************************* @attention** Copyright (c) 2023 STMicroelectronics.* All rights reserved.** This software is licensed under terms that can be found in the LICENSE file* in the root directory of this software component.* If no LICENSE file comes with this software, it is provided AS-IS.********************************************************************************/
/* USER CODE END Header *//* Includes ------------------------------------------------------------------*/
#include "usbd_cdc_if.h"/* USER CODE BEGIN INCLUDE */
#include "main.h"
/* USER CODE END INCLUDE *//* Private typedef -----------------------------------------------------------*/
/* Private define ------------------------------------------------------------*/
/* Private macro -------------------------------------------------------------*//* USER CODE BEGIN PV */
/* Private variables ---------------------------------------------------------*/
USBD_CDC_LineCodingTypeDef LineCoding =
{115200, /* Baud-rate:115200*/0x00, /* Stop Bit:1*/0x00, /* Verification: none*/0x08 /* Data bits: 8*/
};void ComPort_Config(void)
{extern UART_HandleTypeDef huart1;extern uint8_t uart1_reconfig_flag;if(HAL_UART_DeInit(&huart1) != HAL_OK){/* Initialization Error */Error_Handler();}/* set the Stop bit */switch (LineCoding.format){case 0:huart1.Init.StopBits = UART_STOPBITS_1;break;case 2:huart1.Init.StopBits = UART_STOPBITS_2;break;default :huart1.Init.StopBits = UART_STOPBITS_1;break;}/* set the parity bit*/switch (LineCoding.paritytype){case 0:huart1.Init.Parity = UART_PARITY_NONE;break;case 1:huart1.Init.Parity = UART_PARITY_ODD;break;case 2:huart1.Init.Parity = UART_PARITY_EVEN;break;default :huart1.Init.Parity = UART_PARITY_NONE;break;}/*set the data type : only 8bits and 9bits is supported */switch (LineCoding.datatype){case 0x07:/* With this configuration a parity (Even or Odd) must be set */huart1.Init.WordLength = UART_WORDLENGTH_8B;break;case 0x08:if(huart1.Init.Parity == UART_PARITY_NONE){huart1.Init.WordLength = UART_WORDLENGTH_8B;}else{huart1.Init.WordLength = UART_WORDLENGTH_9B;}break;default :huart1.Init.WordLength = UART_WORDLENGTH_8B;break;}huart1.Init.BaudRate = LineCoding.bitrate;huart1.Init.HwFlowCtl = UART_HWCONTROL_NONE;huart1.Init.Mode = UART_MODE_TX_RX;huart1.Init.OverSampling = UART_OVERSAMPLING_16;if(HAL_UART_Init(&huart1) != HAL_OK){/* Initialization Error */Error_Handler();}uart1_reconfig_flag = 1;
}/* USER CODE END PV *//** @addtogroup STM32_USB_OTG_DEVICE_LIBRARY* @brief Usb device library.* @{*//** @addtogroup USBD_CDC_IF* @{*//** @defgroup USBD_CDC_IF_Private_TypesDefinitions USBD_CDC_IF_Private_TypesDefinitions* @brief Private types.* @{*//* USER CODE BEGIN PRIVATE_TYPES *//* USER CODE END PRIVATE_TYPES *//*** @}*//** @defgroup USBD_CDC_IF_Private_Defines USBD_CDC_IF_Private_Defines* @brief Private defines.* @{*//* USER CODE BEGIN PRIVATE_DEFINES */
/* USER CODE END PRIVATE_DEFINES *//*** @}*//** @defgroup USBD_CDC_IF_Private_Macros USBD_CDC_IF_Private_Macros* @brief Private macros.* @{*//* USER CODE BEGIN PRIVATE_MACRO *//* USER CODE END PRIVATE_MACRO *//*** @}*//** @defgroup USBD_CDC_IF_Private_Variables USBD_CDC_IF_Private_Variables* @brief Private variables.* @{*/
/* Create buffer for reception and transmission */
/* It's up to user to redefine and/or remove those define */
/** Received data over USB are stored in this buffer */
uint8_t UserRxBufferFS[APP_RX_DATA_SIZE];/** Data to send over USB CDC are stored in this buffer */
uint8_t UserTxBufferFS[APP_TX_DATA_SIZE];/* USER CODE BEGIN PRIVATE_VARIABLES *//* USER CODE END PRIVATE_VARIABLES *//*** @}*//** @defgroup USBD_CDC_IF_Exported_Variables USBD_CDC_IF_Exported_Variables* @brief Public variables.* @{*/extern USBD_HandleTypeDef hUsbDeviceFS;/* USER CODE BEGIN EXPORTED_VARIABLES *//* USER CODE END EXPORTED_VARIABLES *//*** @}*//** @defgroup USBD_CDC_IF_Private_FunctionPrototypes USBD_CDC_IF_Private_FunctionPrototypes* @brief Private functions declaration.* @{*/static int8_t CDC_Init_FS(void);
static int8_t CDC_DeInit_FS(void);
static int8_t CDC_Control_FS(uint8_t cmd, uint8_t* pbuf, uint16_t length);
static int8_t CDC_Receive_FS(uint8_t* pbuf, uint32_t *Len);/* USER CODE BEGIN PRIVATE_FUNCTIONS_DECLARATION *//* USER CODE END PRIVATE_FUNCTIONS_DECLARATION *//*** @}*/USBD_CDC_ItfTypeDef USBD_Interface_fops_FS =
{CDC_Init_FS,CDC_DeInit_FS,CDC_Control_FS,CDC_Receive_FS
};/* Private functions ---------------------------------------------------------*/
/*** @brief Initializes the CDC media low layer over the FS USB IP* @retval USBD_OK if all operations are OK else USBD_FAIL*/
static int8_t CDC_Init_FS(void)
{/* USER CODE BEGIN 3 *//* Set Application Buffers */USBD_CDC_SetTxBuffer(&hUsbDeviceFS, UserTxBufferFS, 0);USBD_CDC_SetRxBuffer(&hUsbDeviceFS, UserRxBufferFS);return (USBD_OK);/* USER CODE END 3 */
}/*** @brief DeInitializes the CDC media low layer* @retval USBD_OK if all operations are OK else USBD_FAIL*/
static int8_t CDC_DeInit_FS(void)
{/* USER CODE BEGIN 4 */return (USBD_OK);/* USER CODE END 4 */
}/*** @brief Manage the CDC class requests* @param cmd: Command code* @param pbuf: Buffer containing command data (request parameters)* @param length: Number of data to be sent (in bytes)* @retval Result of the operation: USBD_OK if all operations are OK else USBD_FAIL*/
static int8_t CDC_Control_FS(uint8_t cmd, uint8_t* pbuf, uint16_t length)
{/* USER CODE BEGIN 5 */switch(cmd){case CDC_SEND_ENCAPSULATED_COMMAND:break;case CDC_GET_ENCAPSULATED_RESPONSE:break;case CDC_SET_COMM_FEATURE:break;case CDC_GET_COMM_FEATURE:break;case CDC_CLEAR_COMM_FEATURE:break;/*******************************************************************************//* Line Coding Structure *//*-----------------------------------------------------------------------------*//* Offset | Field | Size | Value | Description *//* 0 | dwDTERate | 4 | Number |Data terminal rate, in bits per second*//* 4 | bCharFormat | 1 | Number | Stop bits *//* 0 - 1 Stop bit *//* 1 - 1.5 Stop bits *//* 2 - 2 Stop bits *//* 5 | bParityType | 1 | Number | Parity *//* 0 - None *//* 1 - Odd *//* 2 - Even *//* 3 - Mark *//* 4 - Space *//* 6 | bDataBits | 1 | Number Data bits (5, 6, 7, 8 or 16). *//*******************************************************************************/case CDC_SET_LINE_CODING: //Get info from PCLineCoding.bitrate = (uint32_t)(pbuf[0] | (pbuf[1] << 8) |\(pbuf[2] << 16) | (pbuf[3] << 24));LineCoding.format = pbuf[4];LineCoding.paritytype = pbuf[5];LineCoding.datatype = pbuf[6];ComPort_Config();//re-config serial portbreak;case CDC_GET_LINE_CODING: //For PC to get infopbuf[0] = (uint8_t)(LineCoding.bitrate);pbuf[1] = (uint8_t)(LineCoding.bitrate >> 8);pbuf[2] = (uint8_t)(LineCoding.bitrate >> 16);pbuf[3] = (uint8_t)(LineCoding.bitrate >> 24);pbuf[4] = LineCoding.format;pbuf[5] = LineCoding.paritytype;pbuf[6] = LineCoding.datatype;break;case CDC_SET_CONTROL_LINE_STATE:break;case CDC_SEND_BREAK:break;default:break;}return (USBD_OK);/* USER CODE END 5 */
}/*** @brief Data received over USB OUT endpoint are sent over CDC interface* through this function.** @note* This function will issue a NAK packet on any OUT packet received on* USB endpoint until exiting this function. If you exit this function* before transfer is complete on CDC interface (ie. using DMA controller)* it will result in receiving more data while previous ones are still* not sent.** @param Buf: Buffer of data to be received* @param Len: Number of data received (in bytes)* @retval Result of the operation: USBD_OK if all operations are OK else USBD_FAIL*/
static int8_t CDC_Receive_FS(uint8_t* Buf, uint32_t *Len)
{/* USER CODE BEGIN 6 */static uint8_t Buff[1024];static uint32_t Buff_index = 0;extern UART_HandleTypeDef huart1;extern uint8_t uart1_txdone_flag;if(uart1_txdone_flag==1){uart1_txdone_flag = 0;memcpy(Buff+Buff_index, Buf, *Len); //Single frame data receivingBuff_index += *Len;uint8_t Buff_t[1024];memcpy(Buff_t, Buff, Buff_index); //Whole data shift for buffer protectionHAL_UART_Transmit_DMA(&huart1, Buff_t, Buff_index);Buff_index = 0;}else{memcpy(Buff+Buff_index, Buf, *Len); //Single frame data receivingBuff_index += *Len;}USBD_CDC_SetRxBuffer(&hUsbDeviceFS, &Buf[0]);USBD_CDC_ReceivePacket(&hUsbDeviceFS);return (USBD_OK);/* USER CODE END 6 */
}/*** @brief CDC_Transmit_FS* Data to send over USB IN endpoint are sent over CDC interface* through this function.* @note*** @param Buf: Buffer of data to be sent* @param Len: Number of data to be sent (in bytes)* @retval USBD_OK if all operations are OK else USBD_FAIL or USBD_BUSY*/
uint8_t CDC_Transmit_FS(uint8_t* Buf, uint16_t Len)
{uint8_t result = USBD_OK;/* USER CODE BEGIN 7 */USBD_CDC_HandleTypeDef *hcdc = (USBD_CDC_HandleTypeDef*)hUsbDeviceFS.pClassData;if (hcdc->TxState != 0){return USBD_BUSY;}USBD_CDC_SetTxBuffer(&hUsbDeviceFS, Buf, Len);result = USBD_CDC_TransmitPacket(&hUsbDeviceFS);/* USER CODE END 7 */return result;
}/* USER CODE BEGIN PRIVATE_FUNCTIONS_IMPLEMENTATION *//* USER CODE END PRIVATE_FUNCTIONS_IMPLEMENTATION *//*** @}*//*** @}*/main.c的完整实现代码：
/* USER CODE BEGIN Header */
/********************************************************************************* @file : main.c* @brief : Main program body******************************************************************************* @attention** Copyright (c) 2023 STMicroelectronics.* All rights reserved.** This software is licensed under terms that can be found in the LICENSE file* in the root directory of this software component.* If no LICENSE file comes with this software, it is provided AS-IS.********************************************************************************/
//Written by Pegasus Yu in 2023
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"
#include "usb_device.h"/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes *//* USER CODE END Includes *//* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */
__IO float usDelayBase;
void PY_usDelayTest(void)
{__IO uint32_t firstms, secondms;__IO uint32_t counter = 0;firstms = HAL_GetTick()+1;secondms = firstms+1;while(uwTick!=firstms) ;while(uwTick!=secondms) counter++;usDelayBase = ((float)counter)/1000;
}void PY_Delay_us_t(uint32_t Delay)
{__IO uint32_t delayReg;__IO uint32_t usNum = (uint32_t)(Delay*usDelayBase);delayReg = 0;while(delayReg!=usNum) delayReg++;
}void PY_usDelayOptimize(void)
{__IO uint32_t firstms, secondms;__IO float coe = 1.0;firstms = HAL_GetTick();PY_Delay_us_t(1000000) ;secondms = HAL_GetTick();coe = ((float)1000)/(secondms-firstms);usDelayBase = coe*usDelayBase;
}void PY_Delay_us(uint32_t Delay)
{__IO uint32_t delayReg;__IO uint32_t msNum = Delay/1000;__IO uint32_t usNum = (uint32_t)((Delay%1000)*usDelayBase);if(msNum>0) HAL_Delay(msNum);delayReg = 0;while(delayReg!=usNum) delayReg++;
}
/* USER CODE END PTD *//* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */
uint8_t CDC_Transmit_FS(uint8_t* Buf, uint16_t Len);
/* USER CODE END PD *//* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */
uint8_t uart1_rxbyte;
uint8_t uart1_rxd[1024];
uint8_t uart1_txd[1024];
uint32_t uart1_rx_index = 0;
uint32_t uart1_rx_index_t = 0;uint8_t uart1_reconfig_flag = 0;
uint8_t uart1_txdone_flag = 1; //0: TX ongoing; 1: TX idle;
/* USER CODE END PM *//* Private variables ---------------------------------------------------------*/
UART_HandleTypeDef huart1;
DMA_HandleTypeDef hdma_usart1_tx;/* USER CODE BEGIN PV *//* USER CODE END PV *//* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_DMA_Init(void);
static void MX_USART1_UART_Init(void);
/* USER CODE BEGIN PFP *//* USER CODE END PFP *//* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 *//* USER CODE END 0 *//*** @brief The application entry point.* @retval int*/
int main(void)
{/* USER CODE BEGIN 1 *//* 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_DMA_Init();MX_USB_DEVICE_Init();MX_USART1_UART_Init();/* USER CODE BEGIN 2 */PY_usDelayTest();PY_usDelayOptimize();HAL_UART_Receive_IT(&huart1, &uart1_rxbyte, 1);/* USER CODE END 2 *//* Infinite loop *//* USER CODE BEGIN WHILE */while (1){if(uart1_reconfig_flag==1){uart1_reconfig_flag = 0;HAL_UART_Receive_IT(&huart1, &uart1_rxbyte, 1); //Start receiving after port re-config}if(uart1_rx_index!=0){memcpy(uart1_txd, uart1_rxd, uart1_rx_index); //Copy datauart1_rx_index_t = uart1_rx_index; //Copy lengthuart1_rx_index = 0; //Receiving index adjustment for new coming datawhile (CDC_Transmit_FS(uart1_txd, uart1_rx_index_t)==USBD_BUSY) PY_Delay_us_t(1); //Send data to USB}/* USER CODE END WHILE *//* USER CODE BEGIN 3 */}/* USER CODE END 3 */
}/*** @brief System Clock Configuration* @retval None*/
void SystemClock_Config(void)
{RCC_OscInitTypeDef RCC_OscInitStruct = {0};RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};RCC_PeriphCLKInitTypeDef PeriphClkInit = {0};/** Initializes the RCC Oscillators according to the specified parameters* in the RCC_OscInitTypeDef structure.*/RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;RCC_OscInitStruct.HSEState = RCC_HSE_ON;RCC_OscInitStruct.HSEPredivValue = RCC_HSE_PREDIV_DIV1;RCC_OscInitStruct.HSIState = RCC_HSI_ON;RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL9;if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK){Error_Handler();}/** Initializes the CPU, AHB and APB buses clocks*/RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK|RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2;RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK){Error_Handler();}PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_USB;PeriphClkInit.UsbClockSelection = RCC_USBCLKSOURCE_PLL_DIV1_5;if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK){Error_Handler();}
}/*** @brief USART1 Initialization Function* @param None* @retval None*/
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 = 115200;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;if (HAL_UART_Init(&huart1) != HAL_OK){Error_Handler();}/* USER CODE BEGIN USART1_Init 2 *//* USER CODE END USART1_Init 2 */}/*** Enable DMA controller clock*/
static 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, 0, 0);HAL_NVIC_EnableIRQ(DMA1_Channel4_IRQn);}/*** @brief GPIO Initialization Function* @param None* @retval None*/
static void MX_GPIO_Init(void)
{
/* USER CODE BEGIN MX_GPIO_Init_1 */
/* USER CODE END MX_GPIO_Init_1 *//* GPIO Ports Clock Enable */__HAL_RCC_GPIOD_CLK_ENABLE();__HAL_RCC_GPIOA_CLK_ENABLE();/* USER CODE BEGIN MX_GPIO_Init_2 */
/* USER CODE END MX_GPIO_Init_2 */
}/* USER CODE BEGIN 4 */
void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{if(huart==&huart1){uart1_rxd[uart1_rx_index++]=uart1_rxbyte;HAL_UART_Receive_IT(&huart1, &uart1_rxbyte, 1);}
}void HAL_UART_TxCpltCallback(UART_HandleTypeDef *huart)
{uart1_txdone_flag = 1;
}
/* USER CODE END 4 *//*** @brief This function is executed in case of error occurrence.* @retval None*/
void Error_Handler(void)
{/* USER CODE BEGIN Error_Handler_Debug *//* User can add his own implementation to report the HAL error return state */__disable_irq();while (1){}/* USER CODE END Error_Handler_Debug */
}#ifdef USE_FULL_ASSERT
/*** @brief Reports the name of the source file and the source line number* where the assert_param error has occurred.* @param file: pointer to the source file name* @param line: assert_param error line source number* @retval None*/
void assert_failed(uint8_t *file, uint32_t line)
{/* USER CODE BEGIN 6 *//* User can add his own implementation to report the file name and line number,ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) *//* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */编译下载后即实现了USB转TTL串口工具。
STM32代码测试
将UART1的收发管脚短接，实现环回场景并行发收测试，连接STM32的USB到PC，打开串口工具进行发收测试，效果如下：
STM32例程下载
STM32F103C6T6 USB转TTL串口例程
STM32F401CCU6 USB转TTL串口例程
扩展模式
增加UART转RS232芯片（MAX3232）电路后，也就成为了USB转RS232串口工具
也可以修改逻辑实现USB转RS422, RS485, CAN等工具
–End–
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STM32实现USB转TTL串口工具
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