#include <reg52.h>
#include <intrins.h>

#define TH833 0xFD			//1200 baud
#define TL833 0x07

#define TH416 0xFE			//2400 baud
#define TL416 0x87

#define TH208 0xFF			//4800 baud
#define TL208 0x48

#define TH104 0xFF			//9600 baud
#define TL104 0xA8


unsigned char bdata dat;
unsigned char bdata din;

sbit TX = P3^1;
sbit RX = P3^0;
sbit out = dat^0;
sbit in = din^7;

void delay1us(unsigned int x)
{
	for(x;x!=0;x--)	
		_nop_();
}

void delayRS()
{
		TR2 = 1;	
		while(!TF2);
		TR2 = 0;
		TF2 = 0;	
}
// TX function
void send_byte(unsigned char x)
{
	unsigned char i;

	RCAP2L = TL833;
	RCAP2H = TH833;
	TL2 = TL833;
	TH2 = TH833;
	
	dat = x;
	TX = 0;
	delayRS();
	for(i=0;i<8;i++)	
	{
	        TX = out;
		delayRS();
		dat = dat >> 1;			 
	}
	TX = 1;
	delayRS();	
}
// RX function
void rec_byte(unsigned char *x)
{
	unsigned char i;
	bit t=1;
	//T2CON = 0x00;
	RCAP2L = TL416;
	RCAP2H = TH416;
	TL2 = TL416;
	TH2 = TH416;


	din = 0;
	while(RX == 1);
	delayRS();delayRS();delayRS();	   // 1.5 bit delay

	for(i=0;i<8;i++)
	{
		in = RX;		   //sample bit
		din = din << 1;
		delayRS();delayRS();	   // 1 bit delay
	}
	*x = din;
	delayRS();
}




void main()
{
	unsigned char i,send[]="SEND A CHARACTERn 15",rec[]="character recieved:";
	unsigned char input='0';
	
	TX = 1;
	T2CON = 0x00;
	RCAP2L = TL833;
	RCAP2H = TH833;
	TL2 = TL833;
	TH2 = TH833;
	while(1)
	{	
	while(send[i])
		{
			send_byte(send[i++]);
			//delay1us(400);
		}
		i=0;

		rec_byte(&input);

		while(rec[i])
		{
			send_byte(rec[i++]);
			delay1us(50);
		}
		send_byte(input);		
		i=0;
	}	

}