[avr-chat] a communication prtocol...where is the error?

[pulkitmidha]

//i am trying to make a routing protocol on atmega8..but my problem is 
//very elementary..sum1 please tell me quickly what the error is? 
//please see the main() i have described the error there 

#include <avr/io.h> 
#define F_CPU 1000000 //1Mhz 
#define UART_BAUD_RATE 4800 //4800 baud 

//#define UART_BAUD_SELECT (F_CPU/(UART_BAUD_RATE*16)-1) 

typedef unsigned char u08; 
u08 byte0,byte1,byte2,byte3,byte4,d,addr='P',flag=0; 
void uart_init(void) 
{ 

UCSRB = (1<<RXEN)|(1<<TXEN); 
UCSRC = ((1<<URSEL) | (3<<UCSZ0));// 8-data, 1 stop-bit, no parity 
UBRRH=0; 
//UBRRL=25; 
UBRRL=12;//(u08)UART_BAUD_SELECT; 
} 
void USART_Transmitt( unsigned char data ) 
{ 
/* Wait for empty transmit buffer */ 
while ( !( UCSRA & (1<<UDRE)) ) 
; 
/* Put data into buffer, sends the data */ 
UDR = data; 
} 


unsigned char USART_Receiver( void ) 
{ 
/* Wait for data to be received */ 
while ( !(UCSRA & (1<<RXC)) ) 
; 
/* Get and return received data from buffer */ 
return UDR; 
} 
void datt(void) 
{ 
d=65;// acqdata(); 
USART_Transmitt('Z'); 
USART_Transmitt(d); 
USART_Transmitt(addr); 
USART_Transmitt(addr); 
} 

void polt(void) 
{ 
USART_Transmitt('Z'); 
USART_Transmitt(byte2 & 0xff); 
USART_Transmitt(byte2); 
USART_Transmitt(0); 
USART_Transmitt(addr); 
} 

void ackr(void) 
{ 
USART_Transmitt('Z'); 
} 

void datf(void) 
{ 
USART_Transmitt('Z'); 
USART_Transmitt(0); 
USART_Transmitt(byte2); 
USART_Transmitt(byte3); 
USART_Transmitt(addr); 
} 

void polr(void) 
{ 
if(byte2==addr) 
datt(); 
else 
polt(); 
} 
/*void datr(void) 
{ 
datf(); 
}*/ 

void main(void) 
{u08 byte0,byte1,byte2,byte3,byte4; 
uart_init(); 
while(!flag) 
{ 
byte0=USART_Receiver(); 
USART_Transmitt(byte0); 

if( byte0 == 'Z' )//here is where the error is!control is not entering this 
// segment even when i give a 'Z' on the hyperterminal..wats more, 
//the code is not similating correctly on avr studio! 

{ 
USART_Transmitt('Q'); 
byte1=USART_Receiver(); 
if(byte1==addr) 
{ 
flag=1; 
byte2=USART_Receiver(); 
byte3=USART_Receiver(); 
byte4=USART_Receiver(); 
} 
} 
} 
if(byte3=='U') 
ackr(); 
else 
if(byte3=='V') 
polr(); 
else datf(); 
} 

//i shall  be very grateful to anyone who URGENTLY replies..thanx..pulkit
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