c3.c

rs485通讯程序实现控制继电器等外围电器

#include <reg51.h>
//#include <AT89X52.h>
#include <stdio.h>
#define RX_PAN_UP 0x40           //
#define RX_PAN_DOWN 0x41         //
#define RX_PAN_LEFT 0x42         //
#define RX_PAN_RIGHT 0x43        //
#define uchar unsigned char
#define uint unsigned int
data uchar buffer[5];           //
data uchar ReadIndex;           //
data uchar point;          //
Uar_Init();
sbit P20=0xA0;
sbit P21=0xA1;
sbit P33=0xB3;
void Translate_RxByte(uchar RxByte);
bit Change_Flag;
void Update_LED();
bit read_flag=0;

Uart_Init()
{
	SCON=0x50;
	TMOD=0x20;
	TH1=0xFD;
	TL1=0xFD;
	TR1=1;
	ES=1;
	EA=1;
	P33=0;
	P21=0;
}

void Serial_int() interrupt 4 using 3
{
	uchar ch;
	if(RI==1)
	{
		RI=0;
		ch=SBUF;
		if(ch==0xFF)
		{
			point=0;
			buffer[point]=ch;
		}
		else
		{
			point++;
			buffer[point]=ch;
			if(point==4)
			{
				read_flag=1;
			}
		}
	}

	if(TI==1)
	{
		TI=0;
	}
}

void send_char(uchar ch)
{
	P33=1;
	SBUF=ch;
	TI=0;
	P33=0;
}

main()
{
	P0=0xFF;
	P1=0xFF;
	P2=0xFF;
	P3=0xFF;
	ReadIndex=0;
	point=0;
	Uart_Init();
	while(1)
	{
		uchar ach;
		if(read_flag==1)
		{
			read_flag=0;
			if((buffer[1]==0xFD) && (buffer[0]==0xFF))// && (buffer[3]==(buffer[1]+buffer[2])))
			{
				Translate_RxByte(buffer[2]);
				ach=buffer[1];
				send_char(ach);
			}
		}
	}
}

void Translate_RxByte(uchar RxByte)
{
	switch(RxByte)
	{
		case RX_PAN_UP:
			P20=0;
			break;
		case RX_PAN_DOWN:
			P20=1;
			break;
		case RX_PAN_LEFT:
			P20=0;
			break;
		case RX_PAN_RIGHT:
			P20=1;
			break;
		default:
			break;
	}
}