atmega128 시리얼 에코 테스트

serialEcho.c

#define F_CPU 16000000UL

#define USART_BAUDRATE 9600               										// baud rate
#define UBRR_VALUE (((F_CPU / (USART_BAUDRATE * 16UL))) - 1)	// Clock, bps to UBRR

#include <avr/io.h>
#include <stdio.h>


void initUART()
{
	// 16bit UBRRn - Split by each 8bit
	UBRR1H = (uint8_t)(UBRR_VALUE>>8);
	UBRR1L = (uint8_t) UBRR_VALUE;
	
	UCSR1C |=  (1 << UCSZ10) | (1 << UCSZ11);	// Data bit - 8bit
	UCSR1C &= ~((1 << UPM11) | (1 << UPM10));	// Parity bit - none
	UCSR1C &= ~(1 << USBS1);		        		// stop  bit - 1bit
	
	UCSR1B=(1 << RXEN1) | (1 << TXEN1);		      	// Enable send, receive
}

void sendByte(uint8_t data) {
	while(!(UCSR1A & (1 << UDRE1))){};	    		// Wait for sending
	UDR1 = data;
}

uint8_t readByte(void) {
	while(!(UCSR1A & (1 << RXC1))){};	      		// Wait for receiving
	return UDR1;
}

void sendString(const char str[]) {
	uint8_t i = 0;
	while (str[i]) {
		sendByte(str[i]);
		i++;
	}
}

int main(void)
{
	initUART();
	char c;
	
	while(1)
	{
		c = readByte();
		sendByte(c);
	}
}