[嵌入式]STM32串口通信配置（USART/UART）

在配置USART和UART之前，得先明白什么是USART和UART以及它们之间有什么区别，其实两者是同步和异步的区别。
UART：universal asynchronous receiver and transmitter通用异步收发器；
USART：universal synchronous asynchronous receiver and transmitter通用同步异步收发器。
一般而言，单片机中，名称为UART的接口一般只能用于异步串行通讯，而名称为USART的接口既可以用于同步串行通讯，也能用于异步串行通讯。
STM32串口引脚如下图所示

一、配置USART1

static unsigned char TxBuffer[256];
static unsigned char TxCounter=0;
static unsigned char count=0; 
extern void CopeSerial1Data(unsigned char ucData);
void Initial_UART1(unsigned long baudrate)
{
 	 //GPIO端口设置
 	GPIO_InitTypeDef GPIO_InitStructure;
	USART_InitTypeDef USART_InitStructure;
	NVIC_InitTypeDef NVIC_InitStructure; 
	RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1 | RCC_APB2Periph_GPIOA, ENABLE);
	//USART1_TX   GPIOA.9
	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;//复用推挽输出
	GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
	GPIO_Init(GPIOA, &GPIO_InitStructure); //初始化   
   //USART1_RX   GPIOA.10
	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;//浮空输入
	GPIO_Init(GPIOA, &GPIO_InitStructure);//初始化
	  
	USART_InitStructure.USART_BaudRate = baudrate;//设置波特率
	USART_InitStructure.USART_WordLength = USART_WordLength_8b;//字长为8位数据格式
	USART_InitStructure.USART_StopBits = USART_StopBits_1;//1个停止位
	USART_InitStructure.USART_Parity = USART_Parity_No ;//无奇偶校验
	USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;//无硬件数据流控制
	USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;//收发模式
	USART_Init(USART1, &USART_InitStructure); //初始化
	USART_ITConfig(USART1, USART_IT_TXE, DISABLE);  
	USART_ITConfig(USART1, USART_IT_RXNE, ENABLE); //开启串口接受中断       
	USART_ClearFlag(USART1,USART_FLAG_TC);
	USART_Cmd(USART1, ENABLE);//使能
	NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;
	NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
	NVIC_InitStructure.NVIC_IRQChannelSubPriority = 7;
	NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
	NVIC_Init(&NVIC_InitStructure);
}

二、配置USART2

由于和前一个配置大同小异，所以只在和前一个不同的地方加入注释

static unsigned char TxBuffer[256];
static unsigned char TxCounter=0;
static unsigned char count=0; 
extern void CopeSerial2Data(unsigned char ucData);
void Initial_UART2(unsigned long baudrate)
{
 	GPIO_InitTypeDef GPIO_InitStructure;
	USART_InitTypeDef USART_InitStructure;
	NVIC_InitTypeDef NVIC_InitStructure; 
	RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2 | RCC_APB2Periph_GPIOA, ENABLE);
	//PA2为TX
	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2;
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
	GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
	GPIO_Init(GPIOA, &GPIO_InitStructure);  
	//PA3为RX  
	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3;
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
	GPIO_Init(GPIOA, &GPIO_InitStructure);
	 
	USART_InitStructure.USART_BaudRate = baudrate;
	USART_InitStructure.USART_WordLength = USART_WordLength_8b;
	USART_InitStructure.USART_StopBits = USART_StopBits_1;
	USART_InitStructure.USART_Parity = USART_Parity_No ;
	USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
	USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
	USART_Init(USART2, &USART_InitStructure); 
	USART_ITConfig(USART2, USART_IT_TXE, DISABLE);    
	USART_ITConfig(USART2, USART_IT_RXNE, ENABLE);
	USART_ClearFlag(USART2,USART_FLAG_TC);	
	USART_Cmd(USART2, ENABLE);
	NVIC_InitStructure.NVIC_IRQChannel = USART2_IRQn;
	NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
	NVIC_InitStructure.NVIC_IRQChannelSubPriority = 8;
	NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
	NVIC_Init(&NVIC_InitStructure);
}

三、配置USART3

static unsigned char TxBuffer[256];
static unsigned char TxCounter=0;
static unsigned char count=0; 
extern void CopeSerial2Data(unsigned char ucData);
void Initial_UART3(unsigned long baudrate)
{
 	GPIO_InitTypeDef GPIO_InitStructure;
	USART_InitTypeDef USART_InitStructure;
	NVIC_InitTypeDef NVIC_InitStructure; 
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART3 | RCC_APB2Periph_GPIOA, ENABLE);
	 RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);   // GPIOB时钟
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART3,ENABLE);
	  USART_DeInit(USART3);
	 //PB10为TX
	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
	GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
	GPIO_Init(GPIOB, &GPIO_InitStructure);    
	//PB1为RX
	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_11;
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
	GPIO_Init(GPIOB, &GPIO_InitStructure);
	 
	USART_InitStructure.USART_BaudRate = baudrate;
	USART_InitStructure.USART_WordLength = USART_WordLength_8b;
	USART_InitStructure.USART_StopBits = USART_StopBits_1;
	USART_InitStructure.USART_Parity = USART_Parity_No ;
	USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
	USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
	USART_Init(USART3, &USART_InitStructure); 
	USART_ITConfig(USART3, USART_IT_TXE, DISABLE);    
	USART_ITConfig(USART3, USART_IT_RXNE, ENABLE);
	USART_ClearFlag(USART3,USART_FLAG_TC);	
	USART_Cmd(USART3, ENABLE);
	NVIC_InitStructure.NVIC_IRQChannel = USART3_IRQn;
	NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
	NVIC_InitStructure.NVIC_IRQChannelSubPriority = 8;
	NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
	NVIC_Init(&NVIC_InitStructure);
}

配置大概就是如此，在笔者的程序中，USART1用来STM32连接电脑上串口助手，USART2、3用来连接两个传感器收发数据，有兴趣的读者可以留言或留下邮箱，笔者看到会及时回复