超声波模块

在蓝桥杯单片机中，超声波模块的TX引脚接到单片机的P1^0端口，RX引脚接到单片机的P1^1端口，设计程序，进行超声波测距，最大测量范围约140cm，用cm作为显示单位，显示在数码管的最左边三位，如果测量距离超出范围，则以“F”作为标记，显示在数码管的最右边一位。

计算距离公式

距离 = 声速 * 发出超声波到接收返回的时间 / 2；

sonic.c

#include <sys.h>void SendSonic()
{uchar i = 8;while(i--){TX = 1;sonic_nop; sonic_nop; sonic_nop; sonic_nop; sonic_nop;sonic_nop; sonic_nop; sonic_nop; sonic_nop; sonic_nop;TX = 0;sonic_nop; sonic_nop; sonic_nop; sonic_nop; sonic_nop;sonic_nop; sonic_nop; sonic_nop; sonic_nop; sonic_nop;}
}uint Rec_Distance()
{uint distance = 0,time = 0;SendSonic();TR1 = 1;//启动定时器0while((RX == 1) && (TF1 == 0));//等待超声波信号返回，或等到测量超出范围TR1 = 0;//停止计数if(TF1 == 0)//正常测量范围{time = TH1;time = (time << 8) | TL1;distance = (uint)time * 0.017 / 12;}else{TF1 = 0;distance = 999;}TH1 = 0;TL1 = 0;return distance;
}

nixie.c

#include <sys.h>uchar Nixie[] = {0XC0, 0XF9, 0XA4, 0XB0, 0X99, 0X92, 0X82, 0XF8, 0X80, 0X90, 0XBF, 0XFF, 0x8e};
//0~9 - 熄灭void DisplayBit(uchar pos,uchar value)
{Select_74HC138(7);P0 = 0XFF;Select_74HC138(6);P0 = _crol_(0X01,pos);Select_74HC138(7);P0 = Nixie[value];Delay(1);Select_74HC138(0);
}void DisplayDistance()
{uint distance;if(flag_wave){distance = Rec_Distance();}if(distance == 999){DisplayBit(7,12);}else{DisplayBit(0,distance / 100);DisplayBit(1,distance / 10 % 10);DisplayBit(2,distance % 10);
//		Select_74HC138(7);
//		P0 = 0XFF;}}

sys.c

#include <sys.h>bit flag_wave = 0;
uchar t = 0;void Select_74HC138(uchar channel)
{switch(channel){case 0: P2 = P2 & 0X1F; break;case 4: P2 = (P2 & 0X1F) | 0X80; break;case 5: P2 = (P2 & 0X1F) | 0XA0; break;case 6: P2 = (P2 & 0X1F) | 0XC0; break;case 7: P2 = (P2 & 0X1F) | 0XE0; break;}
}void Init_System()
{Select_74HC138(4);P0 = 0XFF;Select_74HC138(5);P0 = 0X00;Select_74HC138(7);P0 = 0XFF;Select_74HC138(0);
}void Delay(uint ms)
{uint i;for(ms; ms > 0; ms--)for(i = 921; i > 0; i--);
}void InitTimer0()//定时1ms
{AUXR |= 0X80;//定时器时钟1T模式TMOD &= 0XF0;//设置定时器模式TL0 = 0X20;TH0 = 0XD1;TF0 = 0;//清除TF0标志TR0 = 1;//定时器0开始计时ET0 = 1;EA = 1;
}void ServiceTimer0() interrupt 1
{uchar t;t++;if(t == 100){t = 0;flag_wave = !flag_wave;}DisplayDistance();
}void InitTimer1()
{AUXR |= 0X40;TMOD &= 0X0F;TL1 = 0;TH1 = 0;TF1 = 0;TR1 = 0;
}

main.c

#include <sys.h>uint distance;void main()
{Init_System();InitTimer0();InitTimer1();while(1){	
//		DisplayDistance();}
}

sys.h

#ifndef _SYS_H_
#define _SYS_H_#include <STC15F2K60S2.H>
#include <INTRINS.H>sbit TX = P1^0;
sbit RX = P1^1;#define uchar unsigned char
#define uint unsigned int
#define sonic_nop {_nop_(); _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); _nop_();};extern bit flag_wave;//sys.h
void Select_74HC138(unsigned char channel);
void Init_System();
void Delay(unsigned int ms);
void InitTimer0();
void InitTimer1();
//nixie.c
void DisplayBit(unsigned char pos,unsigned char value);
void DisplayDistance();//sonic.c
void SendSonic();
unsigned int Rec_Distance();#endif