AVR单片机atmega16串口中断接收和发送程序

// Crystal: 8.0000Mhz
//AVR单片机atmega16串口中断接收和发送程序。接收到字符后再发送出去
#include
#include
unsigned char com_in_buf[1];
void port_init(void)
{
 PORTA = 0xFF;
 DDRA  = 0xFF;
 PORTB = 0x00;
 DDRB  = 0x00;
 PORTC = 0x00; 
 DDRC  = 0x00;
 PORTD = 0x00;
 DDRD  = 0x00;
}

//UART0 initialize 
// desired baud rate: 9600 
// actual: baud rate:9615 (0.2%) 
// char size: 8 bit 
// parity: Disabled 
void uart0_init(void)
{
 UCSRB = 0x00; //disable while setting baud rate
 UCSRA = 0x00;
 UCSRC = BIT(URSEL) | 0x06;
 UBRRL = 0x33; //set baud rate lo
 UBRRH = 0x00; //set baud rate hi
 UCSRB = 0x98;
}

void send_data(unsigned char back)
{
  while( !( UCSRA & (1<   UDR=back;
}

#pragma interrupt_handler uart0_rx_isr:12
void uart0_rx_isr(void)
{
 //uart has received a character in UDR
 com_in_buf[0]=UDR;
 send_data(com_in_buf[0]);
}

//call this routine to initialize all peripherals
void init_devices(void)
{
 //stop errant interrupts until set up
 CLI(); //disable all interrupts
 port_init();
 uart0_init();

 MCUCR = 0x00;
 GICR  = 0x00;
 TIMSK = 0x00; //timer interrupt sources
 SEI(); //re-enable interrupts
 //all peripherals are now initialized
}

void main(void)
{
  char j;
  init_devices();
  while(1)
  {
    for(j=1;j<100;j++)
  ;
  }
}