单片机向串口发送键盘指令，串口助手在同一个指令上一直不停的跑 代码如下 哪位大神帮帮忙

Question

#include
#include
#define uchar unsigned char
#define uint unsigned int
uchar key_scan(); uchar key;
void SendOneByte(unsigned char c)

{

SBUF = c;
while(TI==0);

TI = 0;

}
void delay(uint k) //延时程序

{

uint i,j;

for(i=k;i>0;i--)

for(j=110;j>0;j--);

}

void main() //主程序

{ uchar b;

TMOD = 0x20; //定时器T1的工作方式2,8位数据自动重装

SCON = 0x50; //串行口的方式1,8位异步收发，波特率可变。

TH1 = 0xfd; // 装定时器1初值.

TL1 = 0xfd;

PCON = 0x00;

EA = 1; //开总中断

ES = 1; //串行口中断源允许

TR1 = 1; //开定时器1

while(1) //循环开始

{

    b=key_scan();       
    switch(b)
    {
    case 1: SendOneByte('1');  break;
    case 2: SendOneByte('2');  break;
    case 3: SendOneByte('3');  break;
    case 4: SendOneByte('4');  break;
    case 5: SendOneByte('5');  break;
    case 6: SendOneByte('6');  break;
    case 7: SendOneByte('7');  break;
    case 8: SendOneByte('8');  break;
    case 9: SendOneByte('9');  break;
    case 0: SendOneByte('0');  break;
    case 11:SendOneByte('U');  break;
    case 12:SendOneByte('Y');  break;
    case 13:SendOneByte('N');  break;
    case 14:SendOneByte('L');  break;
    case 15:SendOneByte('D');  break;
    case 16:SendOneByte('R');  break;
   default :break;  
    }

}

}

uchar key_scan()
{
uchar cord_h,cord_l,x;//行列值
P1=0xf0; //行线输出全为0
cord_h=P1&0xf0; //读入列线值
if(cord_h!=0xf0) //先检测有无按键按下
{
delay(80); //去抖
if(cord_h!=0xf0)
{
cord_h=P1&0xf0; //读入列线值

P1=cord_h|0x0f; //输出当前列线值
cord_l=P1&0x0f; //读入行线值
x=cord_h+cord_l;//键盘最后组合码值
switch ( x )

{
case 0xee: key=1; break;
case 0xde: key=2; break;
case 0xbe: key=3; break;
case 0x7e: key=4; break;
case 0xed: key=5; break;
case 0xdd: key=6; break;
case 0xbd: key=7; break;
case 0x7d: key=8; break;
case 0xeb: key=9; break;
case 0xdb: key=0; break;
case 0xbb: key=11; break;
case 0x7b: key=12; break;
case 0xe7: key=13; break;
case 0xd7: key=14; break;
case 0xb7: key=15; break;
case 0x77: key=16; break;
}

}
}

return key;

}

Answer 1

我觉你的这个问题的原因是：b的值在上一次按键按下后就是一个固定的值了，比如你按下0xee之后，在按下第二个键之前，b的值就一直都是1，
所以while循环里会一直发送1.所以你需要在没有按键按下的时候，让keyscan()返回一个while的switch中没有的值，也就是执行default。

switch ( x )

{
case 0xee: key=1; break;
case 0xde: key=2; break;
case 0xbe: key=3; break;
case 0x7e: key=4; break;
case 0xed: key=5; break;
case 0xdd: key=6; break;
case 0xbd: key=7; break;
case 0x7d: key=8; break;
case 0xeb: key=9; break;
case 0xdb: key=0; break;
case 0xbb: key=11; break;
case 0x7b: key=12; break;
case 0xe7: key=13; break;
case 0xd7: key=14; break;
case 0xb7: key=15; break;
case 0x77: key=16; break;
}

在这个switch中加一个default：key=0;break;

switch ( x )

{
case 0xee: key=1; break;
case 0xde: key=2; break;
case 0xbe: key=3; break;
case 0x7e: key=4; break;
case 0xed: key=5; break;
case 0xdd: key=6; break;
case 0xbd: key=7; break;
case 0x7d: key=8; break;
case 0xeb: key=9; break;
case 0xdb: key=0; break;
case 0xbb: key=11; break;
case 0x7b: key=12; break;
case 0xe7: key=13; break;
case 0xd7: key=14; break;
case 0xb7: key=15; break;
case 0x77: key=16; break;
default:key=0;break;
}