求US-100（模块）超声波测距的C语言程序，基于51单片机的，3Q哦~

Question

求基于51单片机的US-100超声波测距C语言程序。需要详细点的具体设计程序，O(∩_∩)O~ US-100模块参考资料：http://wenku.baidu.com/view/65e63e35a32d7375a41780ce.html
性能要求：实现2--150cm的测距，测得结果保留4位有效数字（取整数），单位：mm。
哪位大神帮帮忙喽，急啊！！！真心谢谢大神了~

Answer 1

#include <reg51.h>
#define uchar unsigned char
#define uint unsigned int
unsigned char code smg[]={0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90,0x88,0x83,0xc6,0xa1,0x86,0x8e,0x00};
sbit tr=P1^0;
sbit ec=P1^1;
uint distance,time,tl,th;
void delay_20us(void )
{
uchar a ;
for(a=0;a<100;a++);
}
void delay(uint a )
{
while(a--);
}
void display(void )
{
P2=0xff;
P2=0xfe;
P0=smg[distance/100];
delay(200);
P2=0xff;
P2=0xfd;
P0=smg[distance%100/10];
delay(200);
P2=0xff;
P2=0xfb;
P0=smg[distance%10];
delay(200);
}
void main(void )
{
uchar i;
TMOD=0X10;
while(1)
{
tr=1; //超声波输入端
delay_20us(); //延时20us
tr=0; //产生一个20us的脉冲
while(ec==0); //等待Echo回波引脚变高电平
TH1=0; //定时器1清零
TL1=0; //定时器1清零
TF1=0; //计数溢出标志
TR1=1; //启动定时器1
while(ec==1);
th=TH1;
tl=TL1;
TL1=0;
TH1=0;
TR1=0; //关闭定时器1
time=th*256+tl;
distance=time*0.017; //厘米 */
display()；

}
}
不懂M我

Answer 2

#include <reg51.h>
#define uchar unsigned char
#define uint unsigned int
unsigned char code smg[]={0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90,0x88,0x83,0xc6,0xa1,0x86,0x8e,0x00};
sbit tr=P1^0;
sbit ec=P1^1;
uint distance,time,tl,th;
void delay_20us(void )
{
uchar a ;
for(a=0;a<100;a++);
}
void delay(uint a )
{
while(a--);
}
void display(void )
{
P2=0xff;
P2=0xfe;
P0=smg[distance/100];
delay(200);
P2=0xff;
P2=0xfd;
P0=smg[distance%100/10];
delay(200);
P2=0xff;
P2=0xfb;
P0=smg[distance%10];
delay(200);
}
void main(void )
{
uchar i;
TMOD=0X10;
while(1)
{
tr=1; //超声波输入端
delay_20us(); //延时20us
tr=0; //产生一个20us的脉冲
while(ec==0); //等待Echo回波引脚变高电平
TH1=0; //定时器1清零
TL1=0; //定时器1清零
TF1=0; //计数溢出标志
TR1=1; //启动定时器1
while(ec==1);
th=TH1;
tl=TL1;
TL1=0;
TH1=0;
TR1=0; //关闭定时器1
time=th*256+tl;
distance=time*0.017; //厘米 */
display()；

}
}