如何在单片机初始化后自动发送字符串

发表于 2007-5-22 11:20

觉得是一个很简单的事，可是在串口调试助手下却无法显示的到，不知道是什么原因呢：
#include <stdio.h>
#include <macros.h>
#include "iom128v.h"
#include "pgmspace.h"

void Usart0_init(void)  //7.3728Mhz频率，设置波特率9.6k，8位数据位，无校验，接收发送使能，1位停止位
{
  UBRR0H=0;
  UBRR0L=47;
  UCSR0B=(1<<RXEN0)|(1<<TXEN0);  //发送接收使能，使用查询方式，故没有使能中断
  UCSR0C=(1<<UCSZ00)|(1<<UCSZ01);  //0x06 8位数据，1位停止位，无校验
}

void Usart0_transmit(unsigned char c)  //查询方式发送接收字符函数
{
  while( !(UCSR0A&(1<<UDRE0)));//等待发送缓冲区为空
  UDR0=c;
  }

unsigned char Usart0_receive(void)
{
  while (!(UCSR0A&(1<<RXC0))) ;
  return UDR0;
}

int main(void)
{
   unsigned int temp;
   Usart0_init();

   Usart0_transmit('A');  //就是为了能发个A，为什么出不来
   while(1)
     {
       Usart0_transmit( Usart0_receive（）);
       for(temp=0;temp<3000;temp++)
     {
  }

发表于 2007-5-23 13:38

看你的初始化也没有错(建议在进行赋值前先把 UCSR0B和 UCSR0C清零)
检查一下硬件吧!
也可以看一下生成的汇编文件,看程序编译后是不是对的!
也可以通过软仿真来看看!

发表于 2007-5-24 22:58

这里有讨论128的串口程序 http://bbs.avrvi.com/htm_data/30/0705/2419.html
//ICC-AVR application builder : 2007-5-20 17:21:25
// Target : M128
// Crystal: 7.3728Mhz
// AVR与虚拟仪器 http://www.avrvi.com
// 古欣整理

#include <iom128v.h>
#include <macros.h>

void port_init(void)
{
PORTA = 0x00;
DDRA = 0x00;
PORTB = 0x00;
DDRB = 0x00;
PORTC = 0x00; //m103 output only
DDRC = 0x00;
PORTD = 0x00;
DDRD = 0x00;
PORTE = 0x00;
DDRE = 0x00;
PORTF = 0x00;
DDRF = 0x00;
PORTG = 0x00;
DDRG = 0x00;
}

//UART0 initialize
// desired baud rate: 9600
// actual: baud rate:9600 (0.0%)
// char size: 8 bit
// parity: Disabled
void uart0_init(void)
{
UCSR0B = 0x00; //disable while setting baud rate
UCSR0A = 0x00;
UCSR0C = 0x06;
UBRR0L = 0x2F; //set baud rate lo
UBRR0H = 0x00; //set baud rate hi
UCSR0B = 0xD8;
}

#pragma interrupt_handler uart0_rx_isr:19
void uart0_rx_isr(void)
{
//uart has received a character in UDR
}

#pragma interrupt_handler uart0_tx_isr:21
void uart0_tx_isr(void)
{
//character has been transmitted
}

//call this routine to initialize all peripherals
void init_devices(void)
{
//stop errant interrupts until set up
CLI(); //disable all interrupts
XDIV = 0x00; //xtal divider
XMCRA = 0x00; //external memory
port_init();
uart0_init();

MCUCR = 0x00;
EICRA = 0x00; //extended ext ints
EICRB = 0x00; //extended ext ints
EIMSK = 0x00;
TIMSK = 0x00; //timer interrupt sources
ETIMSK = 0x00; //extended timer interrupt sources
SEI(); //re-enable interrupts
//all peripherals are now initialized
}

void USART_Init( unsigned int baud )
{
/* 设置波特率*/
UBRR0H = (unsigned char)(baud>>8);
UBRR0L = (unsigned char)baud;
/* 接收器与发送器使能*/
UCSR0B = (1<<RXEN0)|(1<<TXEN0);
/* 设置帧格式: 8 个数据位, 2 个停止位 */
UCSR0C = (1<<USBS0)|(3<<UCSZ00);
}

void USART_Transmit( unsigned char data )
{
/* 等待发送缓冲器为空 */
while ( !( UCSR0A & (1<<UDRE0)) )
;
/* 将数据放入缓冲器，发送数据*/
UDR0 = data;
}

unsigned char USART_Receive( void )
{
/* 等待接收数据*/
while ( !(UCSR0A & (1<<RXC0)) )
;
/* 从缓冲器中获取并返回数据*/
return UDR0;
}

void main(void)
{
unsigned char tmp;
init_devices();
while(1)
{
if(UCSR0A&(1<<RXC0))
{
tmp=USART_Receive();
USART_Transmit(tmp);
}
}
}

http://bbs.avrvi.com/attachment/Mon_0705/30_1_8c07d1fa4020c37.jpg

[AVR单片机] 如何在单片机初始化后自动发送字符串

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