本实验基于STM32CubeMX实现对STM32开发板的配置，通过串口发送指令控制 LED 和蜂鸣器的状态，同时返回指令信息。并且通过预定义选择是否保持其中一个LED保持闪烁。程序下载
基于STM32CubeMX 实现串口通信控制 LED 和蜂鸣器
1. 软件与硬件
1.1 硬件要求：
1.2 软件要求：
2. STM32CubeMX配置开发板
2.1 Pinout & Configuration
2.2 Clock Configuration
2.3 Project Manager
3. 程序代码
3.1 usart.c
3.2 main.c
4. 程序分析
4.1 主要功能
4.2 程序流程
4.3 主要函数
（1）ALIENTEK ELITE STM32F103 开发板 （STM32F103ZET6 芯片）
（2）USB转TTL 模块
（1）Java Runtime Environment (JRE) 1.8.0 版本
（2）STM32CubeMX 5.6.1 版本
（3）IAR Embedded Workbench 8.0
（4）串口调试工具
LED 0：PB5
LED 1：PE5
BEEP 蜂鸣器：PB8
USART1_TX：PA9
USART1_RX：PA10
(1) GPIO 配置
LED 0、LED1、蜂鸣器设置为Output Push Pull 并设置上拉电阻，使之维持在高电平。
(2) RCC（Reset and Clock Control）时钟控制器配置
(3) USART1 配置
设置为异步模式并使能中断
USART 参数设置
程序下载：https://download.csdn.net/download/frozennet/12587600
实现printf的重定向
/* USER CODE BEGIN 0 */ /****************************************************************** *@brief Retargets the C library printf function to the USART. *@param None *@retval None ******************************************************************/ #include "stdio.h" #ifdef __GNUC__ #define PUTCHAR_PROTOTYPE int _io_putchar(int ch) #else #define PUTCHAR_PROTOTYPE int fputc(int ch, FILE *f) #endif /* __GNUC__*/ PUTCHAR_PROTOTYPE { HAL_UART_Transmit(&huart1, (uint8_t *)&ch, 1, 0xFFFF); return ch; } /* USER CODE END 0 */（1）添加头文件
/* Private includes ----------------------------------------------------------*/ /* USER CODE BEGIN Includes */ #include <stdio.h> #include <string.h> /* USER CODE END Includes */（2）添加预定义
/* Private define ------------------------------------------------------------*/ /* USER CODE BEGIN PD */ /* Uncomment this line to Disable LED Blink*/ //#define LED_BLINK_DISABLE /* Uncomment this line to Enable LED Blink*/ #define LED_BLINK_ENABLE #define Uart1_RxBufferSIZE 255 /* Define the size of buffer zone*/ /* USER CODE END PD */（3）添加变量
/* Private variables ---------------------------------------------------------*/ /* USER CODE BEGIN PV */ __IO ITStatus UartReady = RESET; /* The flag of interruption*/ char Uart1_RxBuffer[Uart1_RxBufferSIZE]; /* The buffer zone */ uint8_t RxBuffer_IT; /* Receive a byte of data */ uint8_t Uart1_Rx_Count = 0; /* Count for receiving */ #ifdef LED_BLINK_ENABLE uint32_t Prior_Tick = 0; /* Record prior tick */ uint32_t Current_Tick = 0; /* Record current tick */ uint32_t Delay_Time = 100; /* Delay time needed */ #endif /* USER CODE END PV */（4）接收第一个字符，并判断是否接收正确
/* USER CODE BEGIN 2 */ /* Receive the first character */ printf("Hello world\r\n"); if(HAL_UART_Receive_IT(&huart1, (uint8_t *)&RxBuffer_IT, 1)== HAL_OK) { } /* USER CODE END 2 */（5）程序主体
/* Infinite loop */ /* USER CODE BEGIN WHILE */ while (1) { #ifdef LED_BLINK_ENABLE Current_Tick = HAL_GetTick(); /* Get current system tick */ if(Current_Tick < Prior_Tick) /* System overflow */ { if(HAL_MAX_DELAY - Prior_Tick + Current_Tick == Delay_Time) { HAL_GPIO_TogglePin(GPIOB, GPIO_PIN_5); Prior_Tick = Current_Tick; printf("Break down\n"); } } if(Current_Tick-Prior_Tick == Delay_Time) /* Satisfy delay */ { HAL_GPIO_TogglePin(GPIOB, GPIO_PIN_5); /* Change LED0 status */ Prior_Tick = Current_Tick; /* Update prior tick with current tick */ } #endif /* UartReady SET by HAL_UART_RxCpltCallback */ if(UartReady == SET) { UartReady = RESET; if(Uart1_Rx_Count >= Uart1_RxBufferSIZE) /* Judge for the overflow of buffer zone */ { Uart1_Rx_Count = 0; /* Reset the count for receiving */ memset(Uart1_RxBuffer,0x00,sizeof(Uart1_RxBuffer)); /* Re-memorize the buffer zone */ } Uart1_RxBuffer[Uart1_Rx_Count] = RxBuffer_IT; /* Save a character in the array */ HAL_UART_Transmit(&huart1, (uint8_t *)&RxBuffer_IT, 1, 0xFFFF); Uart1_Rx_Count++; HAL_UART_Receive_IT(&huart1, (uint8_t *)&RxBuffer_IT, 1); /* Continue to receiving */ if((Uart1_RxBuffer[Uart1_Rx_Count-4] == 0x30)&& (Uart1_RxBuffer[Uart1_Rx_Count-2] == 0x0D) && (Uart1_RxBuffer[Uart1_Rx_Count-1] == 0x0A)) { switch(Uart1_RxBuffer[Uart1_Rx_Count-3]) { #ifdef LED_BLINK_DISABLE case 0x31: HAL_GPIO_TogglePin(GPIOB, GPIO_PIN_5); /* Change LED0 status */ break; #endif case 0x32: HAL_GPIO_TogglePin(GPIOE, GPIO_PIN_5); /* Change LED1 status */ break; case 0x33: HAL_GPIO_TogglePin(GPIOB, GPIO_PIN_8); /* Buzzer open */ HAL_Delay(500); HAL_GPIO_TogglePin(GPIOB, GPIO_PIN_8); /* Buzzer close */ HAL_Delay(3000); HAL_GPIO_TogglePin(GPIOB, GPIO_PIN_8); /* Buzzer open */ HAL_Delay(500); HAL_GPIO_TogglePin(GPIOB, GPIO_PIN_8); /* Buzzer close */ break; default: break; } Uart1_Rx_Count = 0; memset(Uart1_RxBuffer,0x00,sizeof(Uart1_RxBuffer)); } } /* end if*/ } /* end while*/ /* USER CODE END WHILE */（6）回调函数
/* USER CODE BEGIN 4 */ /* UART receives completely callback */ void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart) { UartReady = SET; /* Reset the flag of interruption */ } /* USER CODE END 4 */通过串口通讯接收指令，控制 LED 和蜂鸣器，指令采取16进制，同时开发板串口并返回接收到的信息。
（1）指令集
30 31 0D 0A：控制 LED 0
30 32 0D 0A：控制 LED 1
30 33 0D 0A：控制蜂鸣器
（2）通过预定义控制 LED 0是否保持闪烁
不闪烁，接受串口控制
/* Uncomment this line to Disable LED Blink*/ #define LED_BLINK_DISABLE保持闪烁，不接受串口控制
/* Uncomment this line to Enable LED Blink*/ #define LED_BLINK_ENABLE（1）HAL_UART_Transmit_IT
（2）HAL_UART_Receive_IT
