#include <reg52.h>
	 sbit L_G = P0^0;				   // Green Led
	 sbit L_R = P0^2;				   // Red Led 
	 sbit buz = P0^4;				   // Buzzer
	 sbit srv = P0^6;				   // Servo 
	 sbit eme2 = P0^7;				   // not used
	 sbit intbut = P3^2; 			   // interrupt pin 
	 unsigned char mychar;
	 unsigned int on, off, rotL, rotR, ctr = 0;
	 unsigned int i, x, y, delay, dly = 0;
	 int RST = 0;	 

	 void main (void)
	 {
	 	
	 	
		// datasheet pg62 setting timer mode
		// Timer 1 = 1	 ( Gate1 = 0, C/T1# = 0, M11 = 2, M01 = 0)
		// Timer 0 = 2	 ( Gate0 = 0, C/T0# = 0, M11 = 0, M01 = 1)
		TMOD = 0x21;			//use Timer1 auto-reload & Timer 0 16 bit timer
		// setting baudrate value using the following eauqation
		//TH1 = 256 - ((Crystal / 384) / Baud)
        //TH1 = 256 - ((18,432,000 / 384) / 9600 )
        //TH1 = 256 - ((48,000) / 9600)
        //TH1 = 256 - 5 = 251		
		TH1 = 0xFB;
		SCON = 0x50;			//8-bit UARTVariable, pg 54
		TR1 = 1;				//start timer

		IT0=1;          //set external interrupt 0 negative edge-triggered
    	EX0=1;          //enable external interrupt 0 interrupt
 	    EA=1;           //enable global interrupt
		
		L_R = 0;
		
		// set the servo position to 90 degrees
		for (ctr = 0; ctr <= 10; ctr++)
			{
				//	_________
				//		     |_____________________
				//	 1.49ms	     19.59ms
				//1.49 on
				for (on = 0; on <= 100; on++);  
				 	{
				  		srv = 0;
				  	}
				//18.1ms off
				for (off = 0; off <= 5900; off++);
				  	{
				  		srv = 1;
					}			
			}
		
		while(1)
			{
			//while(RI == 0);		//wait to receive
			mychar = SBUF;		//save serial input value in mychar
			if (mychar == 'U')
			{
				// servo up, active state
				// set the servo position to 0 degrees
				L_G = 0;        //Green LED on
				L_R = 1;		//Red LED off		
				
				for (rotL = 0; rotL <= 10; rotL++)
					{ 
					//	_________
					//		     |_____________________
					//	 0.955ms	     18.087ms
					//0.955ms on
					//was 185 change to 150
					for (on = 0; on <= 650; on++);  
				 		{
				  			srv = 0;
				  		}
					//18.087ms off
					for (off = 0; off <= 5250; off++);
				  		{
				  			srv = 1;
						} 
					}
			}
			
			else if (mychar == 'D')
			{
				// Servo down, active state
				// set the servo position to 180 degrees
				L_G = 0; 		//Green LED on
				L_R = 1;		//Red LED off
				for (rotR = 0; rotR <= 10; rotR++)
					{				
					//	_________
					//		     |_____________________
					//	 1.809ms	     17.575ms
					//1.809ms on
					for (on = 0; on <= 550; on++);  
				 		{
				  			srv = 0;
				  		}
						//17.575ms off
					for (off = 0; off <= 5315; off++);
				  		{
				  			srv = 1;
						} 
					}
			}			
						
			}
			
	 }

	 void turn_on(void) interrupt 0
	 {		
		EA = 0;
		i, x, y, delay, dly = 0;
		RST = 0;

		
		L_G = 1;        //Switch off green LED
		
		// 1 timer value shall be 20ms
		// 500 timer values = 500 * 20ms = 10s
		// now timer step
			
		// Timer 0 step = Crystal/12
		//              = 18,432,000/12
		//              = 1536000Hz
			
		// Time = 1/Frequency
		//      = 1/1536000
		//      = 651.041666nS
			
		// 1 timer step = 651.041666nS, 
		//         ?    = 20ms 
		// answer = 20msec / 651.0416667nSec 
		//        = 30720 steps

		// Now TFO overflows at FFFFh 
		// therefore 65536 - 30720 = 34816  
		// 34816 dec = 8800h
		// Therefore setting THO = 88h and TLO = 00h

		// Now including the LED and Buzzer emergency PWM
		
		// From the Keil debugger using performance graph it was found
		// that the delay for flicketing the LED and buzzer takes
		// Delay start A time = 0.000292
		// Delay stop A time = 0.034318
		// Therfore total delay time A = 0.034318 - 0.000292
		//                             = 0.034026 seconds
		 
		// Now if we add the delays together we get
		// Total delay = (delay Start A till Delay Stop A + 20ms  by Timer)
		//             = (0.034026 + 20ms)
		//             =  0.054026        

		// Now recalculating the for loop for the time
		// 1 timer step + delay time = 0.55ms
		// 10s = ?
		// timer steps = 10/55ms
		//             = 182 
		
		while (((i != 182) && (intbut == 0)) || (RST == 0))
		{
			for (i = 0; i < 182; i++)
			{
				//Delay A - start
				for (x = 0; x <= 5200; x++);  
				  {
				  L_R = 0;		//Red led on for 0.1sec
				  buz  = 0;		//Buzzer on for 0.1 sec
				  }
				
				for (y = 0; y <= 5200; y++);
				{
				   L_R = 1;	//Red Led off for 0.1sec
				   buz = 1;	//Buzzer of for 0.1sec
				}
			 	//Delay A - stop
				
				//start timer
				TH0 = 0x88;		//set 20ms
		    	TL0 = 0x00;	     
				TR0 = 1;		//start timer
				while(TF0 == 0);

				if  ((i >= 181) && (intbut == 0))
					{
						RST = 1;	 //exit interrupt loop
						TR0 = 0;     // stop the timer
			            TF0 = 0;     // clear timer 0 overflow flag						
						
						
					    eme2 = 0;
						for ( delay = 0; delay <= 10000; delay++)
						{
						for (dly = 0; dly <= 100; dly++)
						{}
						}
				
						eme2 = 1;
						
						
					}
				else if ((i <= 181) && (intbut == 1) && (RST == 0))
					{
					i = 0; //restart timer for loop if emergency is not pressed
					}
		
			
			}
			
						 
		}	
	   RST = 0; //for Good Practice
	   EA = 1;
	}