rs485 half duplex with atmega8

#include "definitions.h"
#include <avr/io.h>
#include <inttypes.h>
#include <stdio.h>
#include "init.h"
#include "ds18x20.h"
#include "onewire.h"
#include "delayintr.h"
#include "util/delay.h"

uint8_t gSensorIDs[MAXSENSORS][OW_ROMCODE_SIZE];
void recieve_enable()
{
	_delay_ms(3);
	PORTC&=0xDF;
}
uint8_t search_sensors(void)
//Searches for sensors on the bus.
{
	PORTC|=0x20;
	uint8_t i;
	uint8_t id[OW_ROMCODE_SIZE];
	uint8_t diff, nSensors;
	
	nSensors = 0;
	
	for( diff = OW_SEARCH_FIRST; 
	diff != OW_LAST_DEVICE && nSensors < MAXSENSORS ; )
	{
		DS18X20_find_sensor( &diff, &id[0] );
		
		if( diff == OW_PRESENCE_ERR ) {
			 
			tx( "No Sensors found  " );
			 
			tx( "  " );
			 
			return 255;
		}
		
		if( diff == OW_DATA_ERR ) {
			 
			tx( "Bus Error   " );
			 
			tx( "    " );
			 
			return 255;
		}
		
		for (i=0;i<OW_ROMCODE_SIZE;i++)
			gSensorIDs[nSensors][i]=id[i];
		
		nSensors++;
	}
	
	return nSensors;
}
void USART0_Transmit(unsigned char data)
{
	while (!(UCSRA & (1<<UDRE)))  ;
	UDR = data;
}

void tx(char *data)
{
	while (*data) USART0_Transmit(*data++);
}
unsigned char rx(void)
{
	while (!(UCSRA & (1<<RXC)))  ;
	return UDR;
}
void USART0_Init(void)
{
		UCSRB |= (1 << RXEN) | (1 << TXEN); 
	UCSRC |= (1<<URSEL) |(1 << UCSZ0)| (1 << UCSZ1);//Use 8-bit char 

	UBRRL = 207; 
	UBRRH = 0x00; 
	PORTC|=0x20;
	tx('a');
	_delay_ms(50);
	recieve_enable();
}
int main ( void )
//The program itself
{
	USART0_Init();
	uint8_t nSensors, i;
	uint8_t subzero, cel, cel_frac_bits;
	uint8_t state = 0;
	DDRB = 128; // oiiiiiii
	PORTB = 0; // iiiiiiii
	DDRD = 68; // ioiiioii
	PORTD = 0; // iiiiiiii
	PORTB=255;
	PORTC |=0x20;
	tx("POWER IS DOWN");
PORTB=00;	_delay_ms(50);

	char s [16];
	unsigned char degree_sign = 0x01;
	init();
	abc:
	PORTC=255;
	tx("enter s\r\n");
	PORTC=0;
	
	char b=rx();
	
	//PORTC=255;
	if (b!='s')
	{
		goto abc;
	}
	for (ever) 
	{
		 nSensors = search_sensors();
		
			delayintr(200);
			
			if (nSensors != 255) 
			{
				if ( DS18X20_start_meas( DS18X20_POWER_PARASITE, NULL ) == DS18X20_OK) 
				{
				//	delay_ms(DS18B20_TCONV_12BIT);
					for ( i=0; i<nSensors; i++ ) 
					{
						if ( DS18X20_read_meas( &gSensorIDs[i][0], &subzero, &cel, &cel_frac_bits) == DS18X20_OK ) 
						{
							if (cel_frac_bits > 9)
							cel_frac_bits = cel_frac_bits / 10;
							if (subzero == 0)
								sprintf(s, "S%d  = %d.%d %cC    ", i+1, cel, cel_frac_bits, degree_sign );
							
							else sprintf(s, "S%d = -%d.%d %cC ", i+1, cel, cel_frac_bits, degree_sign);
							tx(s);
							tx("\r");
						}
				
					PORTB=255;
				
					
					}
					tx(".\n");
					goto abc;
				}
			}
	//	}
	//
		
	}
	return 0;
}