UART mit CP2102

/* Funktionen zum Senden und Empfangen eines Bytes im Polling

* Ein empfangenes Zeichen wieder senden und am PortB ausgeben * Pinbelegung der UART-Schnittstelle: Tx = PD1, Rx = PD0

* Controller: ATmega88 @ 16MHz Quarz extern

*/

#include <avr/io.h>

#define FOSC 16000000                // Set clock Speed in Hz

#define BAUD 9600                   // Set baud rate

#define UBRR_Value FOSC/16/BAUD-1   // Set baud rate value in baud rate register

void USART_Init( uint16_t ubrr)

{

  UBRR0H = (uint8_t)(ubrr >> 8);        // Set baud rate in high- and low-register

  UBRR0L = (uint8_t)ubrr;             // Set low-register always after high-register

  UCSR0C = (1<<UCSZ01)|(1<<UCSZ00);   // Set frame format: 8data, 1stop bit

  UCSR0B = (1<<RXEN0)|(1<<TXEN0);     // Enable receiver and transmitter

}

void USART_Transmit(uint8_t data)

{

  while ( !( UCSR0A & (1<<UDRE0)) );    // Wait for empty transmit buffer

  UDR0 = data;                        // Put data into buffer, sends the data

}

uint8_t USART_Receive(void)

{

  while ( !(UCSR0A & (1<<RXC0)) );  // Wait for data to be received

  return UDR0;                        // Get and return received data from buffer

}

/**** Flush Receive-Buffer (entfernen evtl. vorhandener ungültiger Werte) ****/

void USART_Flush(void)

{

  uint8_t dummy;

  while (UCSR0A & (1<<RXC0))

  dummy = UDR0;

}

int main( void )

{

  uint8_t data;

  USART_Init(UBRR_Value);     // Init UART

  USART_Flush();              // Flush Receive-Buffer

  DDRB = 0xFF;                // alle PINs an PortB als Ausgänge

  while(1)

  {

    USART_Transmit(data = USART_Receive());     // receive on byte, send it

    PORTB = data;                               // and write to Port B

  }

}