#include<iom16v.h>
#include <macros.h>
#define key (PIND&0x04)          //定義按鍵PD2
/*****************函數(shù)原型聲明************************/
void USART_Init(unsigned int baud);
void USART_Transmit(unsigned char dat);
void delayms(unsigned int t);
unsigned char USART_Receive(void);
/******************接收中斷函數(shù)****************************/
#pragma interrupt_handler uart0_rx_isr:12
void uart0_rx_isr(void)
{ unsigned char dat;
   if(UCSRA&(1<<RXC)){  //把要接收的數(shù)據(jù)全部接收
   dat=UDR; 
   USART_Transmit(dat);
   }
}	
/*****************************************************/
void main(void)
{ unsigned char rec;
    PORTB=0xff;
    DDRB=0xff;
    PORTD=0x07;
	DDRD=0x02;
	UCSRA=0x00;
    USART_Init(71);//波特為9600，外部晶振11.0592
	SEI();
    while(1)
	{ 	
	   if(key==0)
	     {            //按鍵按下發(fā)送一字節(jié)數(shù)據(jù)
	     delayms(10);
		 if(key==0){
		 while(!key);
		 USART_Transmit(0x22);
		           }
	     }
     }		 
}

/******************USART初始化***********************/    
void USART_Init(unsigned int baud)
 {
  UBRRH=(unsigned char)(baud>>8);
  UBRRL=(unsigned char)baud;  //設(shè)定波特率
  UCSRB=0x98;                 //使能接收和發(fā)送,開接收中斷
  UCSRC=0x8e;                 //設(shè)置幀格式8數(shù)據(jù)位，2停止位
 }
/************發(fā)送函數(shù)****************************/
void USART_Transmit(unsigned char dat)
 {
   while(!(UCSRA&(1<<UDRE)));
   UDR=dat;
 }
/************接收函數(shù)*****************************/
unsigned char USART_Receive(void)
 {
  while(!(UCSRA&(1<<RXC)));
  return UDR;
 }
/**********延時*********************************/
void delayms(unsigned int t)
 {
   unsigned int i,j;
   for(i=0;i<t;i++)
    for(j=0;j<100;j++);
 }