PC和ATMEGA128串口通信

#include
#define RXEN0 4
#define TXEN0 3
#define RXCIE0 7
#define UDRE0 5
#define UCSZ00 1
#define UCSZ01 2
#define UCSZ02 2
#define RXC0 7
char str[20];

unsigned char in; 
void Uar_init(void); 
void COM_send(void);

interrupt[19] void uart0(void)
{     
        bit flag=1; 
       str[in]=UDR0; 
       if(str[in]=='$') //$为停止标志
       {
       UCSR0B&=~(1<        str[in]='\0';
       COM_send(); //发送接受的字符串
       in=0; 
       
       flag=0;
       UCSR0B|=(1<        }
       if(flag)
       in++;
      

}

void Uar_init(void)
{

in=0;
UCSR0B=(1< UBRR0L=0x2f;
UBRR0H=0x00;
UCSR0C=(1<

}                           
    
void COM_send(void)
{
   unsigned char point=0;
    while(str[point]!='\0')                                  
   { 
    
    while(!(UCSR0A&(1<     UDR0=str[point];
    point++; 
    }   
}

void main(void)
{     

Uar_init(); 
    
       #asm('sei');//全局中断开启

       while(1);

}