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从STM32开始的RoboMaster生活:进阶篇 III [UART & USART]
1.0 什么是UART和USART?有什么区别嘛?
1.1 UART定义Universal Asynchronous Receiver/Transmitter:通用异步收发传输器,是一种串行异步收发协议,应用十分广泛。UART工作原理是将数据的二进制位一位一位的进行传输。在UART通讯协议中信号线上的状态位高电平代表’1’低电平代表’0’。当然两个设备使用UART串口通讯时,必须先约定好传输速率和一些数据位。分类属于并行传输,通常1字节数据的8位同时传输,结束后再继续传第2个字节,如同波浪一般,一波一波传输。 1.2 UART与USART的区别 从图上可以看出整个传输过程。首先,在没有数据传输任务的时候,互相之间都是高电平 ( 1 ) ,然后,在有传输任务的时候,有1.5字节宽的起始信号,然后开始传输真正的信号,结束任务后,再给1.5字节宽的结束信号,最后回归没有数据传输的高电平。 USART是UART的升级版,区别在于多了CLK线,在CLK没有信号的时候,就表明没有数据传输任务,有CLK信号的时候,就是正在传输信号,并且CLK提供了时钟同步功能,效验也更精确。但在实际使用的时候,其实并不会感觉UART和USART有很大的区别,除非接触非常底层的东西。 2.0 UART和USART在哪里?UART
尽管大疆第一个图中标明的是USART7,但是其实只能使用异步通讯,也就是普通的UART。
尽管大疆第一个图中标明的是USART8,但是其实只能使用异步通讯,也就是普通的UART。
USART
DJI ON BOARD SDK
这个是大疆预留的官方接口,与一般的USART的接线不同,不能直接使用,也不推荐使用。
3.0 UART和USART有啥用?4.0 UART和USART的两种不同使用模式
4.1 Polling- HAL_StatusTypeDef HAL_UART_Transmit(UART_HandleTypeDef *huart, uint8_t *pData, uint16_t Size, uint32_t Timeout);
复制代码- HAL_StatusTypeDef HAL_UART_Receive(UART_HandleTypeDef *huart, uint8_t *pData, uint16_t Size, uint32_t Timeout);
复制代码 4.2 Interrupt
- HAL_StatusTypeDef HAL_UART_Transmit_IT(UART_HandleTypeDef *huart, uint8_t *pData, uint16_t Size);
复制代码参数
huart:指向UART引脚配置结构体 pData:指向需要传输的字符串 Size:传输数据的字节大小
返回值
- HAL_StatusTypeDef HAL_UART_Receive_IT(UART_HandleTypeDef *huart, uint8_t *pData, uint16_t Size);
复制代码参数
huart:指向UART引脚配置结构体 pData:指向需要传输的字符串 Size:传输数据的字节大小
返回值
这里的函数并不是直接接收数据,而是表明开启UART的Interrupt模式接收完数据后,该UART的Interrupt模式会自动关闭,需要再手动开启
- void HAL_UART_TxCpltCallback(UART_HandleTypeDef *huart) {
- ......
- }
复制代码- void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart) {
- ......
- }
复制代码 5.0 练习项目
5.1 项目简介5.2 芯片配置5.3 项目代码我只放了main.c,完整的工程文件可以在 这里找到! Src/main.c
- /* USER CODE BEGIN Header */
- /**
- ******************************************************************************
- * @file : main.c
- * @brief : Main program body
- ******************************************************************************
- * @attention
- *
- * <h2><center>© Copyright (c) 2020 STMicroelectronics.
- * All rights reserved.</center></h2>
- *
- * This software component is licensed by ST under BSD 3-Clause license,
- * the "License"; You may not use this file except in compliance with the
- * License. You may obtain a copy of the License at:
- * opensource.org/licenses/BSD-3-Clause
- *
- ******************************************************************************
- */
- /* USER CODE END Header */
-
- /* Includes ------------------------------------------------------------------*/
- #include "main.h"
-
- /* Private includes ----------------------------------------------------------*/
- /* USER CODE BEGIN Includes */
- #include "string.h"
- /* USER CODE END Includes */
-
- /* Private typedef -----------------------------------------------------------*/
- /* USER CODE BEGIN PTD */
-
- /* USER CODE END PTD */
-
- /* Private define ------------------------------------------------------------*/
- /* USER CODE BEGIN PD */
- /* USER CODE END PD */
-
- /* Private macro -------------------------------------------------------------*/
- /* USER CODE BEGIN PM */
-
- /* USER CODE END PM */
-
- /* Private variables ---------------------------------------------------------*/
- UART_HandleTypeDef huart7;
-
- /* USER CODE BEGIN PV */
-
- /* USER CODE END PV */
-
- /* Private function prototypes -----------------------------------------------*/
- void SystemClock_Config(void);
- static void MX_GPIO_Init(void);
- static void MX_UART7_Init(void);
- /* USER CODE BEGIN PFP */
-
- /* USER CODE END PFP */
-
- /* Private user code ---------------------------------------------------------*/
- /* USER CODE BEGIN 0 */
- char readBuf[1];
- /* 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_UART7_Init();
- /* USER CODE BEGIN 2 */
- HAL_UART_Receive_IT(&huart7,(uint8_t*)readBuf,1);
- /* USER CODE END 2 */
-
- /* Infinite loop */
- /* USER CODE BEGIN WHILE */
- while (1)
- {
- /* 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};
-
- /** Configure the main internal regulator output voltage
- */
- __HAL_RCC_PWR_CLK_ENABLE();
- __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE3);
- /** Initializes the CPU, AHB and APB busses clocks
- */
- RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
- RCC_OscInitStruct.HSIState = RCC_HSI_ON;
- RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
- RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
- if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
- {
- Error_Handler();
- }
- /** Initializes the CPU, AHB and APB busses clocks
- */
- RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
- |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
- RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSI;
- RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
- RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
- RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
-
- if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
- {
- Error_Handler();
- }
- }
-
- /**
- * @brief UART7 Initialization Function
- * @param None
- * @retval None
- */
- static void MX_UART7_Init(void)
- {
-
- /* USER CODE BEGIN UART7_Init 0 */
-
- /* USER CODE END UART7_Init 0 */
-
- /* USER CODE BEGIN UART7_Init 1 */
-
- /* USER CODE END UART7_Init 1 */
- 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;
- if (HAL_UART_Init(&huart7) != HAL_OK)
- {
- Error_Handler();
- }
- /* USER CODE BEGIN UART7_Init 2 */
-
- /* USER CODE END UART7_Init 2 */
-
- }
-
- /**
- * @brief GPIO Initialization Function
- * @param None
- * @retval None
- */
- static void MX_GPIO_Init(void)
- {
- GPIO_InitTypeDef GPIO_InitStruct = {0};
-
- /* GPIO Ports Clock Enable */
- __HAL_RCC_GPIOG_CLK_ENABLE();
- __HAL_RCC_GPIOE_CLK_ENABLE();
- __HAL_RCC_GPIOF_CLK_ENABLE();
-
- /*Configure GPIO pin Output Level */
- HAL_GPIO_WritePin(GPIOG, LD8_Pin|LD7_Pin|LD6_Pin|LD5_Pin
- |LD4_Pin|LD3_Pin|LD2_Pin|LD1_Pin, GPIO_PIN_RESET);
-
- /*Configure GPIO pin Output Level */
- HAL_GPIO_WritePin(LD_RED_GPIO_Port, LD_RED_Pin, GPIO_PIN_RESET);
-
- /*Configure GPIO pin Output Level */
- HAL_GPIO_WritePin(LD_GREEN_GPIO_Port, LD_GREEN_Pin, GPIO_PIN_RESET);
-
- /*Configure GPIO pins : LD8_Pin LD7_Pin LD6_Pin LD5_Pin
- LD4_Pin LD3_Pin LD2_Pin LD1_Pin */
- GPIO_InitStruct.Pin = LD8_Pin|LD7_Pin|LD6_Pin|LD5_Pin
- |LD4_Pin|LD3_Pin|LD2_Pin|LD1_Pin;
- GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
- GPIO_InitStruct.Pull = GPIO_NOPULL;
- GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
- HAL_GPIO_Init(GPIOG, &GPIO_InitStruct);
-
- /*Configure GPIO pin : LD_RED_Pin */
- GPIO_InitStruct.Pin = LD_RED_Pin;
- GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
- GPIO_InitStruct.Pull = GPIO_NOPULL;
- GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
- HAL_GPIO_Init(LD_RED_GPIO_Port, &GPIO_InitStruct);
-
- /*Configure GPIO pin : LD_GREEN_Pin */
- GPIO_InitStruct.Pin = LD_GREEN_Pin;
- GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
- GPIO_InitStruct.Pull = GPIO_NOPULL;
- GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
- HAL_GPIO_Init(LD_GREEN_GPIO_Port, &GPIO_InitStruct);
-
- }
-
- /* USER CODE BEGIN 4 */
- void HAL_UART_RxCpltCallback(UART_HandleTypeDef *UartHandle){
- switch(readBuf[0]){
- case 'r':
- HAL_GPIO_TogglePin(LD_RED_GPIO_Port,LD_RED_Pin);
- HAL_UART_Transmit(&huart7,(uint8_t*)"LED_RED!\r\n",strlen("LED_RED!\r\n"),HAL_MAX_DELAY);
- break;
- case 'g':
- HAL_GPIO_TogglePin(LD_GREEN_GPIO_Port,LD_GREEN_Pin);
- HAL_UART_Transmit(&huart7,(uint8_t*)"LED_GREEN!\r\n",strlen("LED_GREEN!\r\n"),HAL_MAX_DELAY);
- break;
- case '1':
- HAL_GPIO_TogglePin(LD1_GPIO_Port,LD1_Pin);
- HAL_UART_Transmit(&huart7,(uint8_t*)"LED1!\r\n",strlen("LED1!\r\n"),HAL_MAX_DELAY);
- break;
- case '2':
- HAL_GPIO_TogglePin(LD2_GPIO_Port,LD2_Pin);
- HAL_UART_Transmit(&huart7,(uint8_t*)"LED2!\r\n",strlen("LED2!\r\n"),HAL_MAX_DELAY);
- break;
- case '3':
- HAL_GPIO_TogglePin(LD3_GPIO_Port,LD3_Pin);
- HAL_UART_Transmit(&huart7,(uint8_t*)"LED3!\r\n",strlen("LED3!\r\n"),HAL_MAX_DELAY);
- break;
- case '4':
- HAL_GPIO_TogglePin(LD4_GPIO_Port,LD4_Pin);
- HAL_UART_Transmit(&huart7,(uint8_t*)"LED4!\r\n",strlen("LED4!\r\n"),HAL_MAX_DELAY);
- break;
- case '5':
- HAL_GPIO_TogglePin(LD5_GPIO_Port,LD5_Pin);
- HAL_UART_Transmit(&huart7,(uint8_t*)"LED5!\r\n",strlen("LED5!\r\n"),HAL_MAX_DELAY);
- break;
- case '6':
- HAL_GPIO_TogglePin(LD6_GPIO_Port,LD6_Pin);
- HAL_UART_Transmit(&huart7,(uint8_t*)"LED6!\r\n",strlen("LED6!\r\n"),HAL_MAX_DELAY);
- break;
- case '7':
- HAL_GPIO_TogglePin(LD7_GPIO_Port,LD7_Pin);
- HAL_UART_Transmit(&huart7,(uint8_t*)"LED7!\r\n",strlen("LED7!\r\n"),HAL_MAX_DELAY);
- break;
- case '8':
- HAL_GPIO_TogglePin(LD8_GPIO_Port,LD8_Pin);
- HAL_UART_Transmit(&huart7,(uint8_t*)"LED8!\r\n",strlen("LED8!\r\n"),HAL_MAX_DELAY);
- break;
- }
- HAL_UART_Receive_IT(&huart7,(uint8_t*)readBuf,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 */
-
- /* 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,
- tex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
- /* USER CODE END 6 */
- }
- #endif /* USE_FULL_ASSERT */
-
- /************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/
复制代码 5.4 效果展示
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