input.c

周界报警的报警控制程序,采用89C52芯片,KEIL 51开发!

//scan the Alarm input
#include "reg52.h"
#include "main.h"


unsigned char data in_buf = 0;
unsigned char data i;
unsigned char data in_status = 0;
unsigned char data P0_status;
extern P0_buf;
extern P2_buf;
extern bit Ysd_flag;


extern void delay50us(unsigned char count);

extern void input(void)
{
 LE = 0;
 for(i=0;i<8;i++)
{
 P0 = 0xFF & (0xFF-i);
 delay50us(1);
 if(com_input == 0)
  {
   in_status = 0x01<<i;
   P0_buf = P0_buf | in_status;
  }
 else
  {
   in_status = 0x01<<i;
   in_status = ~in_status;
   P0_buf = P0_buf & in_status;
  }
 }
 delay50us(1);
 P0 = ~P0_buf;

 P2_buf = P0_buf; 
 P0_buf = P0;
 LE = 1;
 }