#include "myuart.h"
#include "avr/io.h"
#include

#define UDRE 5
#define RXEN 4
#define TXEN 3
#define UCSZ0 1
#define RXC 7
#define RXCIE 7

ISR(USART0_RX_vect)//接收中斷
{
unsigned char dummy;
while ( UCSR0A & (1< {
dummy = UDR0;
}
USART_Transmit(dummy);
}

void USART_Transmit(unsigned char data)//發(fā)送字節(jié)
{
/* 等待發(fā)送緩沖器為空 */
while ( !( UCSR0A & (1< ;
/* 將數據放入緩沖器，發(fā)送數據 */
UDR0 = data;
}

void myuart_init(void)
{
//關總中斷
cli();
//4MHZ晶振，設置波特率
UCSR0A &= 0x02; //不倍頻
unsigned char baud;
baud = 25; //9600
UBRR0H = (unsigned char)(baud>>8);
UBRR0L = (unsigned char)baud;
// 接收器與發(fā)送器使能，接收中斷允許
UCSR0B = (1< // 設置幀格式: 8 個數據位, 1個停止位
UCSR0C = (3< //關于中斷
//開總中斷
sei();
}