Microcontroller Example 12.2
#include"reg51.h"
#define FOSC 18432000L
#define BAUD 115200
sfr AUXR = 0x8E;
bit busy=0;
xdata char menu []={
"\r\n--Display Press buttons information --\r\n"};
void I0_KeyDelay(void)
{
unsigned char i;
i=60;
while (i--);
}
void SendData(unsigned char dat)
{
while (busy);
SBUF=dat;
busy=1;
}
void SendString(char *s)
{
while (*s!='\0')
SendData(*s++);
}
void uart1() interrupt 4
{
if(RI)
RI=0;
if(TI)
TI=0;
busy=0;
}
void main()
{
unsigned char c1_new,c1_old=0,c1;
SCON=0x50;
AUXR=0x40;
TL1=(65536-((FOSC/4)/BAUD));
TH1=(65536-((FOSC/4)/BAUD))>>8;
TR1=1;
ES=1;
EA=1;
SendString(&menu);
while(1){
P0=0xF0;
I0_KeyDelay();
c1_new=P0&0xF0;
if(c1_new!=c1_old)
{
c1_old =c1_new;
if(c1_new!=0xF0)
{
P0=0xFE;
I0_KeyDelay();
c1_new=P0;
switch(c1_new)
{
case 0xee:c1=0;break;
case 0xde:c1=4;break;
case 0xbe:c1=8;break;
case 0x7e:c1=12;break;
default:;
}
P0=0xFD;
I0_KeyDelay();
c1_new=P0;
switch(c1_new)
{
case 0xed:c1=1;break;
case 0xdd:c1=5;break;
case 0xbd:c1=9;break;
case 0x7d:c1=13;break;
default:;
}
P0=0xFB;
I0_KeyDelay();
c1_new=P0;
switch(c1_new)
{
case 0xeb:c1=2;break;
case 0xdb:c1=6;break;
case 0xbb:c1=10;break;
case 0x7b:c1=14;break;
default:;
}
P0=0xF7;
I0_KeyDelay();
c1_new=P0;
switch(c1_new)
{
case 0xe7:c1=3;break;
case 0xd7:c1=7;break;
case 0xb7:c1=11;break;
case 0x77:c1=15;break;
default : ;
}
SendString("\r\n press #");
if (c1<10)
SendData(c1+0x30);
else if(c1==10)
SendString("10");
else if (c1==11)
SendString("11");
else if (c1==12)
SendString("12");
else if (c1==13)
SendString("13");
else if (c1==14)
SendString("14");
else if (c1==15)
SendString("15");
SendString("button\r\n");
}
}
}
}