本实验所要实现的功能是:STM32F1通过USART1实现与PC机对话,STM32F1的USART1收到PC机发来的数据后原封不动的返回给PC机显示。同时使用D1指示灯不断闪烁提示系统正常运行。程序框架如下:
(1)初始化USART1,并使能串口接收中断等
(2)编写USART1中断函数
(3)编写主函数
main.c
#include "system.h"
#include "led.h"
#include "SysTick.h"
#include "usart.h"
int main()
{
u8 i;
SysTick_Init(72);
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);//中断优先级分组
LED_Init();
USART1_Init(9600);
while(1)
{
i++;
if(i%20 ==0)
{
led1=!led1;//LED1闪,用来指示主程序循环是否运行
}
delay_ms(10);
}
}
usart.c
#include "usart.h"
void USART1_Init(u32 BoudRate)
{
GPIO_InitTypeDef GPIO_InitStructure;
USART_InitTypeDef USART_InitStructure;
NVIC_InitTypeDef NVIC_InitStructure;
RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1,ENABLE);//使能USART1时钟
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA,ENABLE); //使能GPIOA时钟
GPIO_InitStructure.GPIO_Pin=GPIO_Pin_9; //PA9为USART1的TXD
GPIO_InitStructure.GPIO_Mode=GPIO_Mode_AF_PP;//
GPIO_InitStructure.GPIO_Speed=GPIO_Speed_50MHz; //
GPIO_Init(GPIOA,&GPIO_InitStructure);
GPIO_InitStructure.GPIO_Pin=GPIO_Pin_10; //PA10为USART1的RXD
GPIO_InitStructure.GPIO_Mode=GPIO_Mode_IN_FLOATING;//
GPIO_Init(GPIOA,&GPIO_InitStructure);
USART_InitStructure.USART_BaudRate = BoudRate;
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(USART1, &USART_InitStructure);
USART_Cmd(USART1, ENABLE); //使能串口1
USART_ClearFlag(USART1, USART_FLAG_TC);//清除串口1发送中断标志位
USART_ITConfig(USART1, USART_IT_RXNE, ENABLE);//开启RXNE(接收中断)
//设置中断优先级,使能中断通道
NVIC_InitStructure.NVIC_IRQChannel= USART1_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority =3;
NVIC_InitStructure.NVIC_IRQChannelSubPriority =3;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
}
void USART1_IRQHandler(void)
{
u8 r;
if(USART_GetITStatus(USART1, USART_IT_RXNE) != RESET)
{
r=USART_ReceiveData(USART1);//开发板接收从电脑发过来的数据
USART_SendData(USART1, r);//开发板再把收到的数据发送回电脑
while(USART_GetFlagStatus(USART1, USART_FLAG_TC)!=SET);//等待,直到发送完成
USART_ClearFlag(USART1, USART_FLAG_TC);//清除串口1发送中断标志位
}
}
usart.h
#ifndef _usart_H
#define _usart_H
#include "system.h"
void USART1_Init(u32 BoudRate);
#endif