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问 //串口通讯 ，PE0-Rxd0，PE1-Txd0，返回的数据是发送的数据
#include <iom128.h>

#define xtal  3686400     //晶振16MHZ
#define baud0 19200     //波特率
#define baud1 19200     //波特率
/*
SFR_B(UBRR0H, 0x90)     // USART0 Baud Rate Register High
SFR_B(UBRR0L, 0x09)     // USART0 Baud Rate Register Low
SFR_B(UCSR0B, 0x0A)     // USART0 Control and Status Register B
SFR_B(UCSR0A, 0x0B)     // USART0 Control and Status Register A
SFR_B(UDR0,   0x0C)     // USART0 I/O Data Register
SFR_B(UCSR0C, 0x95)     // USART0 Control and Status Register C
*/
/*****************************
   串口初始化
// USART0 initialization
// Communication Parameters: 8 Data, 1 Stop, No Parity
// USART0 Receiver: On
// USART0 Transmitter: On
// USART0 Mode: Asynchronous
******************************/
void init_uart0(void)
{
UCSR0B = 0x00; //disable while setting baud rate
UCSR0A = 0x00;
UCSR0C =(1<<UCSZ01)|(1<<UCSZ00);//8bit+1bit stop
UBRR0L=(xtal/16/(baud0+1))%256;
UBRR0H=(xtal/16/(baud0+1))/256;
UCSR0B =(1<<RXEN0)|(1<<TXEN0)|(1<<RXCIE0);//RXCEN TXCEN RXCIE      
}
/*****************************
  发送数据函数
******************************/
void trans_byte(unsigned char d)
{
while ( !( UCSR0A & (1<<UDRE0)) )
    ;    // Wait for empty transmit buffer
UDR0 = d;              
}
/******************************
  接收数据函数
*******************************/
unsigned char rece_byte( void )
{
while ( !(UCSR0A & (1<<RXC0)) )
    ;    // Wait for data to be received
return UDR0;
}
/***************************
         主  函  数
****************************/
void main(void)
{
  //PORTA=0;
  //DDRA=0xff;
  init_uart0();                 
  while(1)
  {
   trans_byte(rece_byte());
   }
}
答 1: 申明:参考了一网友先前发布的代码,在此致谢.IAR 编译. 用丁丁的SSCOM3.2测试.