STM32学习笔记（7）：USART串口的使用
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//RCC时钟配置
void RCC_cfg()
{
//定义错误状态变量
ErrorStatus HSEStartUpStatus;
//将RCC寄存器重新设置为默认值
RCC_DeInit();
//打开外部高速时钟晶振
RCC_HSEConfig(RCC_HSE_ON);
//等待外部高速时钟晶振工作
HSEStartUpStatus = RCC_WaitForHSEStartUp();
if(HSEStartUpStatus == SUCCESS)
{
//设置AHB时钟(HCLK)为系统时钟
RCC_HCLKConfig(RCC_SYSCLK_Div1);
//设置高速AHB时钟(APB2)为HCLK时钟
RCC_PCLK2Config(RCC_HCLK_Div1);
//设置低速AHB时钟(APB1)为HCLK的2分频
RCC_PCLK1Config(RCC_HCLK_Div2);
//设置FLASH代码延时
FLASH_SetLatency(FLASH_Latency_2);
//使能预取指缓存
FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable);
//设置PLL时钟，为HSE的9倍频 8MHz * 9 = 72MHz
RCC_PLLConfig(RCC_PLLSource_HSE_Div1, RCC_PLLMul_9);
//使能PLL
RCC_PLLCmd(ENABLE);
//等待PLL准备就绪
while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET);
//设置PLL为系统时钟源
RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);
//判断PLL是否是系统时钟
while(RCC_GetSYSCLKSource() != 0x08);
}
//打开GPIO时钟，复用功能，串口1的时钟
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_GPIOB | RCC_APB2Periph_AFIO | RCC_APB2Periph_USART1, ENABLE);
}
//IO口配置
void GPIO_cfg()
{
GPIO_InitTypeDef GPIO_InitStructure;
//PA9作为US1的TX端，打开复用，负责发送数据
GPIO_StructInit(&GPIO_InitStructure);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_Init(GPIOA , &GPIO_InitStructure);
//PA10作为US1的RX端，负责接收数据
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
GPIO_Init(GPIOA, &GPIO_InitStructure);
//LED显示串口正在发送/接收数据
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
GPIO_Init(GPIOB, &GPIO_InitStructure);
}
//串口初始化
void USART_cfg()
{
USART_InitTypeDef USART_InitStructure;
//将结构体设置为缺省状态
USART_StructInit(&USART_InitStructure);
//波特率设置为115200
USART_InitStructure.USART_BaudRate = 115200;
//一帧数据的宽度设置为8bits
USART_InitStructure.USART_WordLength = USART_WordLength_8b;
//在帧结尾传输1个停止位
USART_InitStructure.USART_StopBits = USART_StopBits_1;
//奇偶失能模式，无奇偶校验
USART_InitStructure.USART_Parity = USART_Parity_No;
//发送/接收使能
USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
//硬件流控制失能
USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
//设置串口1
USART_Init(USART1, &USART_InitStructure);
//打开串口1的中断响应函数
USART_ITConfig(USART1, USART_IT_RXNE, ENABLE);
//打开串口1
USART_Cmd(USART1, ENABLE);
}
//配置中断
void NVIC_cfg()
{
NVIC_InitTypeDef NVIC_InitStructure;
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2); //选择中断分组2
NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQChannel; //选择串口1中断
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0; //抢占式中断优先级设置为0
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; //响应式中断优先级设置为0
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //使能中断
NVIC_Init(&NVIC_InitStructure);
}
然后在stm32f10x_it.c文件中找到相应的中断处理函数，并填入一下内容。注意在stm32f10x_it.c中，要声明一下外部变量RX_status
extern FlagStatus RX_status;
void USART1_IRQHandler(void)
{
GPIO_SetBits(GPIOB, GPIO_Pin_5);