STM32_USART2

usart.h

  usart.h如下：

#ifndef __USART_H
#define __USART_H
#include "stdio.h"

extern u8 USART_RX_BUF[];
extern u8 USART_RX_STA;

void uart2_init ( u32 bound );
#endif

usart.c

  usart.c如下：

#include "sys.h"
#include "usart.h"

#if 1
#pragma import(__use_no_semihosting)

struct __FILE {
    
    
    int handle;
};

FILE __stdout;

void _sys_exit ( int x ) {
    
    
    x = x;
}

int fputc ( int ch, FILE *f ) {
    
    
    while ( ( USART2->SR & 0X40 ) == 0 );

    USART2->DR = ( u8 ) ch;
    return ch;
}
#endif

u8 USART_RX_BUF[64];
u8 USART_RX_STA = 0;

void uart2_init ( u32 bound ) {
    
    
    GPIO_InitTypeDef GPIO_InitStructure;
    USART_InitTypeDef USART_InitStructure;
    NVIC_InitTypeDef NVIC_InitStructure;
    /* 注意！ */
    RCC_APB2PeriphClockCmd ( RCC_APB2Periph_GPIOA, ENABLE );
    RCC_APB1PeriphClockCmd ( RCC_APB1Periph_USART2, ENABLE );
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_Init ( GPIOA, &GPIO_InitStructure );
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
    GPIO_Init ( GPIOA, &GPIO_InitStructure );
    NVIC_InitStructure.NVIC_IRQChannel = USART2_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 3;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init ( &NVIC_InitStructure );
    USART_InitStructure.USART_BaudRate = bound;
    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_RXNE, ENABLE );
    USART_Cmd ( USART2, ENABLE );
}

void USART2_IRQHandler ( void ) {
    
    
    u8 Res;

    if ( USART_GetITStatus ( USART2, USART_IT_RXNE ) != RESET ) {
    
    
        Res = USART_ReceiveData ( USART2 );

        if ( ( USART_RX_STA & 0x80 ) == 0 ) {
    
    
            if ( USART_RX_STA & 0x40 ) {
    
    
                if ( Res != 0x0a ) {
    
    
                    USART_RX_STA = 0;
                } else {
    
    
                    USART_RX_STA |= 0x80;
                }
            } else {
    
    
                if ( Res == 0x0d ) {
    
    
                    USART_RX_STA |= 0x40;
                } else {
    
    
                    USART_RX_BUF[USART_RX_STA & 0X3F] = Res;
                    USART_RX_STA++;

                    if ( USART_RX_STA > 63 ) {
    
    
                        USART_RX_STA = 0;
                    }
                }
            }
        }
    }
}

main.c

  main.c如下：

#include "delay.h"
#include "sys.h"
#include "usart.h"
#include "led.h"

int main ( void ) {
    
    
    SystemInit();
    delay_init ( 72 );
    NVIC_Configuration();
    uart2_init ( 9600 );
    LED_Init();

    while ( 1 ) {
    
    
        LED0 = !LED0;
        printf ( "hello, world\r\n" );

        if ( USART_RX_STA & 0x80 ) {
    
    
            u8 t;
            u8 len = USART_RX_STA & 0x3f; // 得到此次接收到的数据长度
            printf ( "\r\n您发送的消息为: " );

            for ( t = 0; t < len; t++ ) {
    
    
                USART2->DR = USART_RX_BUF[t];

                while ( ( USART2->SR & 0X40 ) == 0 ); // 等待发送结束
            }

            printf ( "\r\n" ); // 插入换行
            USART_RX_STA = 0;
        }

        delay_ms ( 500 );
    }
}