AVR/ EIA-485 Hardwareseitig Problem oder Software / Pegel

#include <avr/io.h>

#include <avr/interrupt.h>

#define UART_BAUD 9600UL

#define F_CPU 8000000UL

#define TESTO_1 0x01

#define TESTO_2 0x02

#define TESTO_3 0x03

#define TESTO_4 0x04

#define RESERVE 0x00

#define  BYTECOUNT 0x02

unsigned char Testo_Send(unsigned char Case,unsigned char Testo_X);

void set_SS_X(unsigned char bit);

void unset_SS_X(unsigned char bit);

void InitUART();

unsigned char ReceiveByte(void);

void TransmitByte(unsigned char data);

void main(void)

{

//set baudrate and enable RX & TX 

InitUART();

DDRC = 0xff;

PORTC = 0xff;

DDRE = 0x04;

EICRA = (1<<ISC01)|(1<<ISC11)|((1<<ISC31));

EIMSK = (1<<INT0)|(1<<INT1)|(1<<INT3);

sei();  

set_SS_X(2);

  while(1) 

       {

    // Warte auf Tasteneingabe, dann Aufruf der Funktion

         }

}

unsigned char Testo_Send(unsigned char Case,unsigned char Testo_X)

{

  unsigned char Data_send[10],Data_receive[25], i=0;

  unsigned int Checksum=0,Value=0;

// 1. Frame in String, dann string ausgeben über 485

  Data_send[9] =  RESERVE;

  //Data[8] =  Checksum;

  Data_send[7] =  Case;

  Data_send[6] =  'P';  // 0x50

  Data_send[5] =  BYTECOUNT;

  Data_send[4] =  0x01;

  Data_send[3] =  RESERVE;  // im Befehl = Reserve

  Data_send[2] =  RESERVE;

  Data_send[1] =  RESERVE;

  Data_send[0] =  Testo_X;

  for (i=0;i<8;i++)

    {

    Checksum +=  Data_send[i];

    }

  //Bildung ZweierKomplement

    Checksum = (unsigned char) (0xff ^ Checksum) + 0x01;

  Data_send[8] =  Checksum;   

  set_SS_X(2); // High

    for (i=0;i<10;i++)

    {

    TransmitByte(Data_send[i]);

    }

  Value = ReceiveByte();

// Do oder for für alle Daten folgt!

  //Value a) Temperature or b) Serial Number 

  return Value;//Data[8]; 

}

ISR (INT0_vect)

{

PORTC = ~Testo_Send( 'U', TESTO_1);

set_SS_X(2);

}

ISR (INT1_vect)

{

PORTC = ~Testo_Send( 'U', TESTO_2);

unset_SS_X(2);

}

ISR (INT3_vect)

{

PORTC = 0xBB;

PORTC = ~ReceiveByte();

}

//Funktion zum rücksetzen der SS als Portausgänge an PORTB an Stelle X auf High

// PORTB von PB0 - PB4 

void set_SS_X(unsigned char bit)

{

  PORTE |= 1<<bit;

}

//Funktion zum setzen der SS als Portausgänge an PORTB an Stelle X auf Low

// PORTB von PB0 - PB4 

void unset_SS_X(unsigned char bit)

{

  PORTE &= ~(1<<bit);

}

void InitUART()

{

UBRR0H = ((F_CPU / (8UL * UART_BAUD)) - 1 )>> 8;

UBRR0L = ((F_CPU / (8UL * UART_BAUD)) - 1);

UCSR0A = (1<<RXC0) | (1<<TXC0);

UCSR0B = (1<<RXEN0)|(1<<TXEN0);

UCSR0C = (1<<UCSZ01)|(1<<UCSZ00);// Asynchron 8N1

}

// --- receive a byte

unsigned char ReceiveByte(void)

{

// polls on receive complete

while(!(UCSR0A & (1<<RXC0)));

return UDR0; //return data

}

// --- transmit a byte

void TransmitByte(unsigned char data)

{

//polls on data register empty,wann darf ich loslegen? 

while(!(UCSR0A & (1<<UDRE0))); 

UDR0 = data; //transmit data

}