uart_multiproc_slave.c

Atmel Uart C51程序（从方式）

/**
 * @file $RCSfile:uart_multiproc_slave.c,v $
 *
 * Copyright (c) 2004 Atmel.
 *
 * Please read file license.txt for copyright notice.
 *
 * @brief This file is an example to use uart with timer in 
 * multiprocessor mode.
 * Slave will echo a received data to master.
 *
 * This file can be parsed by Doxygen for automatic documentation
 * generation.
 * Put here the functional description of this file within the software
 * architecture of your program.
 *
 * @version $Revision: 1.0 $ $Name:  $
 */

/* @section  I N C L U D E S */
#include "reg_c51.h"

char uart_data;
bit TxOK=0;
bit echo=0;

/**
 * FUNCTION_PURPOSE: This file set up uart in mode 3 (9 bits uart) with
 * timer 1 in baud rate generator mode.
 * FUNCTION_INPUTS: void
 * FUNCTION_OUTPUTS: P3.1(TXD) serial output
 */
void main (void) 
{
	SCON = 0xF0;					  /* uart in mode 3 (9 bit), REN=1 */
   SADDR=0x03;                  /* local address */ 
   SADEN=0xFF;                  /* address mask */
	TMOD = TMOD | 0x20 ;         /* Timer 1 in mode 2 */
	TH1  = 0xFD;                 /* 9600 Bds at 11.059MHz */
	TL1  = 0xFD; 				  	  /* 9600 Bds at 11.059MHz */
	ES = 1; 						     /* Enable serial interrupt */
	EA = 1;						     /* Enable global interrupt */
   TR1 = 1;                     /* Timer 1 run */

   while(1)                     /* endless */
      {
         while(!echo);          /* wait data to echo */
         echo = 0;              /* disable echo */

         TB8 = 1;               /* address mode */ 
         TxOK=1;                /* set software flag */ 
         SBUF = 0x01;           /* send master adress */
         while(TxOK);           /* wait the stop bit transmition */

         TB8 = 0;               /* data mode */
         TxOK=1;                /* set software flag */ 
         SBUF = uart_data;      /* send data */ 
         while(TxOK);           /* wait the stop bit transmition */
      }
}		

/**
 * FUNCTION_PURPOSE: serial interrupt, receive data to master
 * FUNCTION_INPUTS: P3.0(RXD) serial input
 * FUNCTION_OUTPUTS: none
 */
void serial_IT(void) interrupt 4 
{
	if (TI == 1) 
	{				                 /* if reception occur */
      TI=0; 			           /* clear transmition flag for next transmition */
      TxOK=0; 			           /* clear software transmition flag */
   }

	if (RI == 1) 
	{				                 /* if reception occur */
	   RI = 0; 			           /* clear reception flag for next reception */
      if(RB8) SM2=0;            /* go into data mode */ 
      else
      {
         uart_data = SBUF;      /* Read receive data */
         SM2=1;                 /* return into address mode after receive data */
         echo=1;                /* enable echo */
      }
	}
}