l239D

#include <inttypes.h>
#include <avr/io.h>
#include <util/delay.h>
#include <stdbool.h>

 /*
  UART-Init:
Berechnung des Wertes für das Baudratenregister
aus Taktrate und gewünschter Baudrate
*/

#ifndef F_CPU
#define F_CPU 16000000UL  // Systemtakt in Hz - Definition als unsigned long beachten
                         // Ohne ergeben sich unten Fehler in der Berechnung
#endif

#define BAUD 9600UL      // Baudrate

void uart_init();               //initialisieren
uint8_t uart_putc(unsigned char c); //Char senden
void uart_puts(char *s);        //String senden
uint8_t uart_getc();               //Char empfangen

// Berechnungen
#define UBRR_VAL ((F_CPU+BAUD*8)/(BAUD*16)-1)   // clever runden
#define BAUD_REAL (F_CPU/(16*(UBRR_VAL+1)))     // Reale Baudrate
#define BAUD_ERROR ((BAUD_REAL*1000)/BAUD) // Fehler in Promille, 1000 = kein Fehler.

#if ((BAUD_ERROR<990) || (BAUD_ERROR>1010))
  #error Systematischer Fehler der Baudrate grösser 1% und damit zu hoch!
#endif

    int main(void)
{
  uart_init();
  uart_puts("Hallo.");
  bool For = false;
  bool Back = false;
  bool Left = false;
  bool Right = false;
  DDRA = 0xFF;
  DDRD = 0xFF;
  while (1)
  {
     uint8_t c;
    c = uart_getc();
switch(c)
        {
    case 'F':For=true;
    break;

    case '3':For=false;
    break;

    case 'B':Back = true;
    break;

    case '4':Back = false;
    break;

    case 'R':Right = true;
    break;

    case '1':Right = false;
    break;

    case 'L':Left = true;
    break;

    case '2':Left = false;
    break;
        }

       if((For == true && Back == false)) //FORWARD (L293D - Enable 1 High, Input 1 High, Input 2 Low, Enable 2 High, Input 3 High, Input 4 Low)
       {
           PORTA = (1<<PA0);
           uart_puts("OK");
           PORTD = (1<<PD6) | (1<<PD5); //Motor 1 - Output 1 High
           _delay_us(50);
       }



       if(Back == true && For == false) //BACKWARDS (L293D - Enable 1 High, Input 1 Low, Input 2 High, Enable 2 High, Input 3 Low, Input 4 High)
       {
           PORTA = (1<<PA1);
           PORTD = 0x0;
           PORTD = (1<<PD6) | (1<<PD4);  //Motor 2 - Output 4 High
           _delay_us(50);
       }


       /*
         if(Right == true && Left == false) //Right (L293D - Enable 1 High, Input 1 High, Input 2 Low, Enable 2 High, Input 3 Low, Input 4 High)
       {
           PORTA = (1<<PA1);
           PORTD = 0x0;

           uart_puts("OK - Right");
       }


         if(Left == true && Right == false) //Left (L293D - Enable 1 High, Input 1 Low, Input 2 High, Enable 2 High, Input 3 High, Input 4 Low)
       {
           PORTA = (1<<PA3);
           PORTD = 0x0;
           PORTD = (1<<PD2) | (1<<PD4); //Motor 1 - Output 2 High
           PORTD = (1<<PD5) | (1<<PD6);  //Motor 2 - Output 4 High
           uart_puts("OK - Left");
       }


       if (For == false && Back == false && Left== false && Right ==false)
       {
           PORTA = (1<<PA1);;
           PORTD = 0x0;
            _delay_us(50);
       }
       */

    }
}

void uart_init(void)
{
    UBRRH = UBRR_VAL >> 8;
    UBRRL = UBRR_VAL & 0xFF;

    UCSRC = (1<<URSEL)|(1<<UCSZ1)|(1<<UCSZ0);  // Asynchron 8N1
    UCSRB |= (1<<RXEN);                        // UART RX einschalten
    UCSRB |= (1<<TXEN);                        // UART TX einschalten
}

/* Zeichen empfangen */
uint8_t uart_getc(void)
{
    while (!(UCSRA & (1<<RXC)))   // warten bis Zeichen verfuegbar
    ;
    return UDR;                   // Zeichen aus UDR an Aufrufer zurueckgeben
}

//Char senden
uint8_t uart_putc(unsigned char c)
{
    while (!(UCSRA & (1<<UDRE)))  // warten bis Senden moeglich
    {
    }

    UDR = c;                      // sende Zeichen
    return 0;
}
//====================================
//String senden
void uart_puts(char *s)
{
    while (*s)
    {   // so lange *s != '\0' also ungleich dem "String-Endezeichen"
        uart_putc(*s);
        s++;
    }
}