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设计要求

驱动超声波传感器，启动距离测量功能,并将其结果显示到数码管上。

按键“S5”定义为参数按键，按下S5按键，设备自动将当前采集的距离数据作为距离参数；

若测量的距离数据超过距离参数，指示灯L1点亮，否则L1熄灭。

距离数据保留小数点后两位有效数字，数码管显示格式如下：

距离为0.40m（数码管高位显示标识符U）

备注

单片机IRC振荡器频率设置为12MHz。

按键模式：BTN；扩展方式：IO模式。

距离参数初始值为0。

代码

sys.h

#ifndef __SYS_H__
#define __SYS_H__#include <STC15F2K60S2.H>
//sys.c
extern float distance_keep;
extern float distance;
void init74hc138(unsigned char n);
void init();
void led1();
//seg_key.c
extern unsigned char Seg_Buff[8];
void Key_Loop();
void Seg_Loop();
void ui();#endif

main.c

#include "sys.h"
#include "intrins.h"
#define NUM 10
sbit TX=P1^0;
sbit RX=P1^1;
bit flag1=0,flag2=0,flag3=0;
void delay(){//超声波延时unsigned char i=0;for(i;i<NUM;i++){_nop_();}
}
void Timer1_Init(void)		//100微秒@12.000MHz
{AUXR |= 0x40;			//定时器时钟1T模式TMOD &= 0x0F;			//设置定时器模式TL1 = 0x50;				//设置定时初始值TH1 = 0xFB;				//设置定时初始值TF1 = 0;				//清除TF1标志TR1 = 1;				//定时器1开始计时ET1 = 1;				//使能定时器1中断EA=1;
}
void send_wave(){//发送超声波脉冲unsigned char i=8;while(i--){TX=1;delay();TX=0;}
}
void re_wave(){//接收超声波并计算距离send_wave();TH0=0;TL0=0;TR0=1;while((RX==1)&&(TF0==0));TR0=0;if(!TF0){distance=(float)(TH0<<8|TL0)*0.017;//cm}else{TF0=0;distance=0.0;}
}
void main(){init();Timer1_Init();TMOD |= 0x01;while(1){if(flag1){flag1=0;Seg_Loop();}if(flag2){flag2=0;Key_Loop();}if(flag3){flag3=0;re_wave();led1();ui();}}
}
void Timer1_Isr(void) interrupt 3
{static unsigned char count1=0;static unsigned char count2=0;static unsigned int count3=0;count1++;count2++;count3++;if(count1==2){count1=0;flag1=1;}if(count2==50){count2=1;flag2=1;}if(count3==1000){count3=0;flag3=1;}
}

sys.c

#include "sys.h"
float distance=0;
float distance_keep=0;
void init74hc138(unsigned char n){P2=(P2&0x1f)|(n<<5);P2&=0x1f;
}
void init(){P0=0x00;init74hc138(5);P0=0xff;init74hc138(4);
}
void led1(){static bit flag=0;if(distance>distance_keep&&!flag){flag=1;P0=0xfe;init74hc138(4);}else if(distance<=distance_keep&&flag){flag=0;P0=0xff;init74hc138(4);}
}

seg_key.c

#include "sys.h"
code unsigned char Seg_Table[]={0xc0,//00xf9,//10xa4,//20xb0,//30x99,//40x92,//50x82,//60xf8,//70x80,//80x90,//90xc1,//U 100xff //熄灭 11
};
unsigned char Seg_Buff[8]={11,11,11,11,11,11,11,11};
unsigned char keyval,keyold,keyup,keydown;
void Key_Loop(){if(P32==0)keyval=5;keydown=keyval&(keyold^keyval);keyup=~keyval&(keyold^keyval);if(keyval==5&&!keyold!=5){distance_keep=distance;}keyold=keyval;keyval=0;
}
void seg(unsigned char addr,num){P0=0xff;init74hc138(7);P0=0x01<<addr;init74hc138(6);P0=Seg_Table[num];if(addr==5) P0&=0x7f;init74hc138(7);
}
void Seg_Loop(){static unsigned char i=0;seg(i,Seg_Buff[i]);i++;if(i==8)i=0;
}
void ui(){Seg_Buff[0]=10;Seg_Buff[1]=11;Seg_Buff[2]=11;Seg_Buff[3]=11;Seg_Buff[4]=11;if(distance>=100)Seg_Buff[5]=(unsigned char)distance/100;elseSeg_Buff[5]=0;if(distance>=10)Seg_Buff[6]=(unsigned char)distance/10%10;elseSeg_Buff[6]=0;if(distance>0)Seg_Buff[7]=(unsigned char)(distance+0.5)%10;elseSeg_Buff[7]=0;
}

测评结果