1.c

基于UCM40的超声波测距函数,可测0.08---2.5米距离,数值精确

#include<reg51.h>
#define uchar unsigned char
#define uint  unsigned int
#define ulong unsigned long

extern void cs_t(void);
extern void delay(uint);
extern void display(uchar*);
data uchar testok;

void main(void)
{
  data uchar dispram[5];
  data uint  i;
  data ulong time;
  P0=0xff;
  P2=0xff;
  TMOD=0X11;
  IE=0X80;
   while(1)
    {
       cs_t();
       delay(1);
	   testok=0;
	   EX0=1;
	   ET0=1;
	   while(!testok)display(dispram);
	   if(1==testok)
		{
 			time=TH0;
 			time=(time<<8)|TL0;
 			time*=172;
 			time/=10000;
 			dispram[0]=(uchar)(time%10);
 			time/=10;
 			dispram[1]=(uchar)(time%10);
 			time/=10;
 			dispram[2]=(uchar)(time%10);
 			dispram[3]=(uchar)(time/10);
			if(0==dispram[3])  dispram[3]=17;
		}
	  else
		{
			dispram[0]=16;
			dispram[1]=16;
			dispram[2]=16;
			dispram[3]=16;

	  }
for(i=0;i<300;i++)display(dispram);
    }
}
void cs_r(void) interrupt 0
{TR0=0;
 ET0=0;
 EX0=0;
 testok=1;
}
void overtime(void) interrupt 1
{
 EX0=0;
 TR0=0;
 ET0=0;
 testok=2;
}