MCU communication program

Transmitter Program

#include
#define uchar unsigned char 
#define uint unsigned int
void delay(uint);
void SET_SYSTEM(void);
uchar KEY_scan(void);

void main() 
{
 uchar data i;
 delay(100);
 SET_SYSTEM();
 while(1)
 {
  i=KEY_scan();
  if(i)
  {
   TI=0;
   SBUF=i;
   while(!TI);
  }
 }
} 
/*************************************************************************************/
void delay(uint t) /* Delay subroutine*/
{
 uchar i;
 while(t--)
 {
  for(i=0;i<125;i++) {}; /* 12 MHz crystal is about 1 ms */
 }
}
/*****************************************************************************************/   
uchar KEY_scan(void) /*Keyboard scanning program (stand-alone)*/
{
 uchar data key;
 
 P1=0xff;
 key=P1;
 if(key==0xff) return 0;
 else 
 {
  delay(10);
  key=P1;
  if(key==0xff) return 0;
  else
  {
   switch(key)
   {
    case 0xfe: return 1;break;
    case 0xfd: return 2;break;
    case 0xfb: return 3;break;
    case 0xf7: return 4;break;
    case 0xef: return 5;break;
    case 0xdf: return 6;break;
    case 0xbf: return 7;break;
    case 0x7f: return 8;break;
    default : return 9;
   }
  }
 }
}                    
/***********************************************************************************/
void SET_SYSTEM(void)
{
 TMOD=0x20; /* Timer 1 works in mode 2 */
 PCON=PCON&0x07;
 TH1=0xfe; /* Set the baud rate*/
 TL1=0xfe;
 SCON=0x50;
 IE=0x00; /* That is, EA=0; turn off all interrupts*/
 TI=0;
 RI=0;
 TR1=1;
}
/****************************************************************************************/

Receiver Program

#include
#define uchar unsigned char 
#define uint unsigned int
void delay(uint);
void SET_SYSTEM(void);
uchar KEY_scan(void);
void LED_display(uchar ,uchar);
uchar xdata IO_8155_order _at_ 0x2100;
uchar xdata IO_8155_PA _at_ 0x2101;
uchar xdata IO_8155_PB _at_ 0x2102;
uchar xdata IO_8155_PC _at_ 0x2103;
uchar data dt=0;
uchar code dig_num[17]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f,0x77,0x7c,0x39,0x5e,0x79,0x71}; /*Segment selection code of common cathode digital tube */
void main() 
{
 delay(200);
 SET_SYSTEM();
 IO_8155_order=0x0d; /* 8155 initialization*/
 while(1)
 {
  LED_display(0,dt);
  P1=dt;
 }
} 
/***** ************************************************** ******************************/
void delay(uint t) /* Delay subroutine*/
{
 uchar i;
 while (t--)
 {
  for(i=0;i<125;i++) {}; /* 12 MHz crystal is about 1 ms */
 }
}
/****************************************** **************************************************/
void LED_display (uchar d_bit,uchar digit) /* LED digital tube display subroutine*/
{ /*d_bit represents the bit selection code, digit represents the number to be displayed */
 IO_8155_PC=d_bit; /* Bit selection code output */
 IO_8155_PA=dig_num[ digit]; /* Segment selection code output */
 delay(10);                      
}
/************************************ ************************************************** ***/
void SET_SYSTEM(void)
{
 TMOD=0x20; /* Timer 1 works in mode 2 */
 PCON=PCON&0x07;
 TH1=0xfe; /* Set baud rate */
 TL1=0xfe;
 SCON=0x50;
 IE=0x90; /* EA=1; ES=1; ET1=0; serial port interrupt is enabled, timer 1 interrupt is disabled*/
 TI=0;
 RI=0;
 TR1=1;
}
/** ************************************************** *********************************/
void RI_RI(void) interrupt 4 
{
 RI=0;
 dt=SBUF;
}