rs485.c

早期用过的一个485通信程序

/*********************************************************************************************************
**
**                                  (c) Copyright 2004-2006
**                                    All Rights Reserved
**
**
**                                    版权所有：朗顿科技
**                                   http://www.ldmcu.com
**
********************************************************************************************************/

#include <REG52.H>                /* special function register declarations   */
                                  /* for the intended 8051 derivative         */

#include <stdio.h>                /* prototype declarations for I/O functions */

bit senenb = 0;
int i_aT,i_bT;
unsigned char Tem;

sbit rs485_com = P3^2;
/*------------------------------------------------
The main C function.  Program execution starts
here after stack initialization.
------------------------------------------------*/
void delay(unsigned char i);

void ser_int (void) interrupt 4 using 1
{
 if(TI == 1)
 {
 	TI = 0;
	senenb = 0;
 }

 if(RI == 1)
 {
 	RI = 0;
	Tem = SBUF;
 	senenb = 1;

 }
}
void main (void) {

/*------------------------------------------------
Setup the serial port for 9600 baud at 11.0592MHz.
------------------------------------------------*/
#ifndef MONITOR51
    SCON  = 0x50;		        /* SCON: mode 1, 8-bit UART, enable rcvr      */
    TMOD |= 0x20;               /* TMOD: timer 1, mode 2, 8-bit reload        */
    TH1   = 0xfd;               /* TH1:  reload value for 9600 baud at 11.0592MHz   */
    TR1   = 1;                  /* TR1:  timer 1 run                          */
	IE    = 0x90;				/* IE:  enable UART interrupter               */
#endif

/*------------------------------------------------
Note that an embedded program never exits (because
there is no operating system to return to).  It
must loop and execute forever.
------------------------------------------------*/
  rs485_com = 0;
  
  while(1)
  {	
  	if(senenb == 1)
	{
	  rs485_com = 1;
	  SBUF = Tem;
	  delay(100);
	}
	else
	{
	  rs485_com = 0;
	}
  }
}

void delay(unsigned char i)
{
	unsigned char j;
	for(i; i > 0; i--)
		for(j = 200; j > 0; j--);
}