#pragma SMALL DB OE
#include <reg51.h>

sbit redlight = P0^0;
sbit yellowlight = P0^1;
sbit greenlight = P0^2;
sbit door = P0^3; 
sbit daynight = P0^4;

void SendSerial(char c) {
        /* initialize..set values for TMOD, TH1 and TCON */
        TMOD = 0x20;    /* configure timer for the correct baud rate */
        TH1 = 0xe6;     /* 1200 bps for 12 MHz clock */
        TCON = 0x00;    /* Set timer to not running */

        /* set the Tx interrupt in SCON to indicate sending data */
        SCON = 0x50;    /* Set Serial IO to  and normal mode */

        /* start timer */
        TR1 = 1;            
        
        /* write character to SBUF */
        SBUF = c;
        
        /* wait for completion of sent data */
        while( (SCON & 0x02) == 0){}
}       

/* Delay function */

void delay() {
int i, j;

     for (i=0; i<1000; i++)
          for (j=0; j<50; j++)
		i=i+0;
}

/* Main function which will blink LED */

void main (void) {

redlight=0;
   
   while(1)  {
	delay();

	/* These are the test lights */
	if (door == 0) {
            greenlight=0;
        }
        else {
	    greenlight=1;
        }

        if (daynight == 1)
	{
	    yellowlight=0;
	}     
	else {
	    yellowlight=1;
	}

	if (door == 0)            /* door closed */
        {
	    SendSerial('x');
	}
	else {                    /* door open */
	    if (daynight == 1)     /* daytime */
	       SendSerial('y');
	    else                  /* nighttime */
	       SendSerial('z'); 
	}  
   }
}