注意波特率是9600

功能：电脑通过串口给单片机发一个字节，单片机收到后又给电脑发回去

、#include

#define uchar unsigned char

#define uint unsigned int

uint temp;

bit flag;

void init_ser1();

main()

{

init_ser1();

while(1)

{

if(RI==1)

{

P1=SBUF;

RI=0;

}

if(flag==1)

{

ES=0;//暂时关闭接收

flag=0;

SBUF=temp;

while(!TI);//等待发送完毕

TI=0;

ES=1;

}

}

}

void sel() interrupt 4

{

RI=0;

P1=SBUF;

temp=SBUF;

flag=1;

}

void init_ser1()

{

REN=1;

SM0=0;

SM1=1;

TMOD=0x20;

TH1=0xFD;

TL1=0xFD;

EA=1;

TR1=1;

ES=1;

}

//======声明======

#include

unsigned char Read_Keyboard();

void RS232_SendData(unsigned char Sdata);

//======延迟函数======

void delay(unsigned int t)

{

for(;t>0;t--); //延迟循环

}

//======UART初始化函数=====

void RS232_Init()

{

SCON=0x50; //0101 0000 UART工作模式1，REN=1(本位为串行接收启用位1:开始接收 0:停止接收)

TMOD=0x20; //0010 0000 Timer1 工作模式2

PCON=0x80; //SMOD1=1

TH1=0xfa; //波特率9600 bps at 11.0592MHZ

TL1=0xfa; //波特率9600 bps at 11.0592MHZ

TR1=1;

}

//======主函数============

void main()

{

unsigned char Keyboard_Status=0xff; //定义按键

RS232_Init(); // 初始化UART

while(1)

{

Keyboard_Status=Read_Keyboard()|0xf0; //读取按键值(屏蔽高4位)

//

switch(Keyboard_Status)

{

case ~0x01:RS232_SendData('A');break;

case ~0x02:RS232_SendData('B');break;

case ~0x04:RS232_SendData('C');break;

case ~0x08:RS232_SendData('D');break;

default:RS232_SendData('X');break;

}

}

}

//===========发送数据函数========

void RS232_SendData(unsigned char Sdata)

{

SBUF=Sdata; //发送数据

while(TI==0); //等待发送结束

TI=0; //清除发送结束标志

}

//========读取按键函数==========

unsigned char Read_Keyboard()

{

unsigned char Keys_Value; //定义按键变量

unsigned char Keys_Temp;

do

{

P1=0xff; //P2口置高,准备读取按键状态

Keys_Temp=P1; //读取按键状态

delay(150); //消抖延时

P1=0xff; //P2口置高,准备读取按键状态

Keys_Value=P1; //读取按键状态

}

while(Keys_Value!=Keys_Temp); //如果读状态不一致,则重复读取键值

return Keys_Value; //返回按键状态值

}