dtmf 8870 interfacing with 8051

#include<reg51.h>

sbit Std=P1^0;  // tone Detector bit


void ini()     // Initialize Timer 1 for serial communication
{
	TMOD=0x20;  //Timer1, mode 2, baud rate 9600 bps
	TH1=0xFD; 	 //Setting a baudrate of 9600
	SCON=0x50;
	TR1=1;
}

void transmit()  // Funtion to transmit serial data
{
	unsigned char output;
	output=(P2 & 0x0F)+48;
	
	switch(output)
	{
		case '1':
		         SBUF='1';
				 break;
		case '2':
		         SBUF='2';
				 break;
		case '3':
		         SBUF='3';
				 break;
		case '4':
		         SBUF='4';
				 break;
		case '5':
		         SBUF='5';
				 break;
		case '6':
		         SBUF='6';
				 break;
		case '7':
		         SBUF='7';
				 break;
	    case '8':
		         SBUF='8';
				 break;
		case '9':
		         SBUF='9';
				 break;
		case ':':
		         SBUF='0';
				 break;
		case ';':
		         SBUF='*';
				 break;
		case '<':
		         SBUF='#';
				 break;
	}
	while(TI==0);
	TI=0;
}

void main()
{ 
 	P2=0xFF;        // Declare P1 as input port.
	ini();
	
	   
	 while(1)
	 {
	 	unsigned long z;
		while(Std == 0);
		transmit();
	    for (z=0;z<=3000;z++);
      }
}