同步博客地址:從STM32開始的RoboMaster生活:進階篇 III [UART & USART]
項目&教程倉庫:-STM32-RoboMaster-
1.0 什麼是UART和USART?有什麼區別嘛?
1.1 UART定義
Universal Asynchronous Receiver/Transmitter:通用異步收發傳輸器,是一種串行異步收發協議,應用十分廣泛。UART工作原理是將數據的二進制位一位一位的進行傳輸。在UART通訊協議中信號線上的狀態位高電平代表’1’低電平代表’0’。當然兩個設備使用UART串口通訊時,必須先約定好傳輸速率和一些數據位。分類屬於並行傳輸,通常1字節數據的8位同時傳輸,結束後再繼續傳第2個字節,如同波浪一般,一波一波傳輸。
1.2 UART與USART的區別
- UART
從圖上可以看出整個傳輸過程。首先,在沒有數據傳輸任務的時候,互相之間都是高電平 ( 1 ) ,然後,在有傳輸任務的時候,有1.5字節寬的起始信號,然後開始傳輸真正的信號,結束任務後,再給1.5字節寬的結束信號,最後迴歸沒有數據傳輸的高電平。
- USART <-- Universal Synchronous/Asynchronous Receiver/Transmitter 通用同步異步接收發送器
USART是UART的升級版,區別在於多了CLK線,在CLK沒有信號的時候,就表明沒有數據傳輸任務,有CLK信號的時候,就是正在傳輸信號,並且CLK提供了時鐘同步功能,效驗也更精確。但在實際使用的時候,其實並不會感覺UART和USART有很大的區別,除非接觸非常底層的東西。
2.0 UART和USART在哪裏?
-
UART
- UART7
儘管大疆第一個圖中標明的是USART7,但是其實只能使用異步通訊,也就是普通的UART。
- UART8
儘管大疆第一個圖中標明的是USART8,但是其實只能使用異步通訊,也就是普通的UART。
-
USART
- USART6
-
DJI ON BOARD SDK
- USART3
這個是大疆預留的官方接口,與一般的USART的接線不同,不能直接使用,也不推薦使用。
3.0 UART和USART有啥用?
-
與PC端通訊
可以作爲Debug的一種手段,或者監控數據流通的方法。
-
與其他設備通訊
比如兩個MCU互相通訊,也就是作爲主從機來使用。
4.0 UART和USART的兩種不同使用模式
4.1 Polling
HAL_StatusTypeDef HAL_UART_Transmit(UART_HandleTypeDef *huart, uint8_t *pData, uint16_t Size, uint32_t Timeout);
- 參數
huart
:指向UART引腳配置結構體pData
:指向需要傳輸的字符串Size
:傳輸數據的字節大小Timeout
:最大等待完成時限,單位爲毫秒,也可以用HAL_MAX_DELAY
來直接無限等待
- 返回值
HAL_StatusTypeDef
:如果傳輸完成,返回HAL_OK
;如果沒有在時限內完成,返回HAL_TIMEOUT
;如果在傳輸出錯,返回HAL_ERROR
;如果該UART正在被佔用,返回HAL_BUSY
HAL_StatusTypeDef HAL_UART_Receive(UART_HandleTypeDef *huart, uint8_t *pData, uint16_t Size, uint32_t Timeout);
- 參數
huart
:指向UART引腳配置結構體pData
:指向需要傳輸的字符串Size
:傳輸數據的字節大小Timeout
:最大等待完成時限,單位爲毫秒,也可以用HAL_MAX_DELAY
來直接無限等待
- 返回值
HAL_StatusTypeDef
:如果傳輸完成,返回HAL_OK
;如果沒有在時限內完成,返回HAL_TIMEOUT
;如果在傳輸出錯,返回HAL_ERROR
;如果該UART正在被佔用,返回HAL_BUSY
4.2 Interrupt
HAL_StatusTypeDef HAL_UART_Transmit_IT(UART_HandleTypeDef *huart, uint8_t *pData, uint16_t Size);
- 參數
huart
:指向UART引腳配置結構體pData
:指向需要傳輸的字符串Size
:傳輸數據的字節大小
- 返回值
HAL_StatusTypeDef
:如果傳輸完成,返回HAL_OK
;如果在傳輸出錯,返回HAL_ERROR
;如果該UART正在被佔用,返回HAL_BUSY
HAL_StatusTypeDef HAL_UART_Receive_IT(UART_HandleTypeDef *huart, uint8_t *pData, uint16_t Size);
- 參數
huart
:指向UART引腳配置結構體pData
:指向需要傳輸的字符串Size
:傳輸數據的字節大小
- 返回值
HAL_StatusTypeDef
:如果傳輸完成,返回HAL_OK
;如果在傳輸出錯,返回HAL_ERROR
;如果該UART正在被佔用,返回HAL_BUSY
這裏的函數並不是直接接收數據,而是表明開啓UART的Interrupt模式
接收完數據後,該UART的Interrupt模式會自動關閉,需要再手動開啓
void HAL_UART_TxCpltCallback(UART_HandleTypeDef *huart) {
......
}
- 在寫代碼的時候,在
main.c
中創建HAL_UART_TxCpltCallback
函數 - 在該函數中填寫UART發送結束後,需要執行的代碼
void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart) {
......
}
- 在寫代碼的時候,在
main.c
中創建HAL_UART_RxCpltCallback
函數 - 在該函數中填寫UART接收結束後,需要執行的代碼
5.0 練習項目
5.1 項目簡介
- 電腦控制LED燈:在電腦上按下r,反轉紅色LED狀態,按下g,反轉綠色LED狀態,按下1~8,反轉對應的LED1~8的狀態,並且返回打印反轉的LED燈號
5.2 芯片配置
- 芯片視角
- GPIO配置列表
- NVIC配置列表
5.3 項目代碼
-
我只放了
main.c
,完整的工程文件可以在這裏找到! -
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****/
5.4 效果展示
http://player.bilibili.com/player.html?aid=96401006&cid=164568509&page=1