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纯干货：

超声波代码：

////     PIC16F877 + HY-SRF05 + LCD03 example//     Written October 2008 , using HITECH PIC16 compiler// // Note - assumes a 20MHz crystal, which is 5MHz timer clock// A 1:4 prescaler is used to give a 1.25MHz timer count (0.8uS per tick)////     This code is Freeware - Use it for any purpose you like./////#include 
   
    #include 
    
      __CONFIG(0x3b32); #define trig RB0#define echo RB1void clrscn(void); // prototypesvoid cursor(char pos);void print(char *p);void setup(void);unsigned int get_srf04(void);char s[21]; // buffer used to hold text to printvoid main(void){    unsigned int range;    setup(); // sets up the PIC16F877 I2C port    clrscn(); // clears the LCD03 disply    cursor(2); // sets cursor to 1st row of LCD03    sprintf(s,"SRF04 Ranger Test");// text, printed into our buffer    print(s); // send it to the LCD03    while(1)     { // loop forever        range = get_srf04();// get range from srf04 (round trip flight time in 0.8uS units)        cursor(24); // sets cursor to 2nd row of LCD03        sprintf(s,"Range = %dcm  ", range/72);// convert to cm        print(s); // send it to the LCD03         cursor(44); // sets cursor to 3rd row of LCD03        sprintf(s,"Range = %dinch  ", range/185);// convert to inches        print(s); // send it to the LCD03         TMR1H = 0; // 52mS delay - this is so that the SRF04 ranging is not too rapid        TMR1L = 0; // and the previous pulse has faded away before we start the next one        T1CON = 0x21; // 1:4 prescale and running        TMR1IF = 0;        while(!TMR1IF);// wait for delay time        TMR1ON = 0; // stop timer     }}unsigned int get_srf04(void){    TMR1H = 0xff; // prepare timer for 10uS pulse    TMR1L = -14;    T1CON = 0x21; // 1:4 prescale and running    TMR1IF = 0;     trig = 1; // start trigger pulse    while(!TMR1IF);// wait 10uS    trig = 0; // end trigger pulse    TMR1ON = 0; // stop timer    TMR1H = 0; // prepare timer to measure echo pulse    TMR1L = 0;    T1CON = 0x20; // 1:4 prescale but not running yet    TMR1IF = 0;    while(!echo && !TMR1IF);// wait for echo pulse to start (go high)    TMR1ON = 1; // start timer to measure pulse    while(echo && !TMR1IF);// wait for echo pulse to stop (go low)    TMR1ON = 0; // stop timer    return (TMR1H<<8)+TMR1L;// TMR1H:TMR1L contains flight time of the pulse in 0.8uS units}void clrscn(void){    SEN = 1; // send start bit    while(SEN); // and wait for it to clear    SSPIF = 0;    SSPBUF = 0xc6;// LCD02 I2C address    while(!SSPIF);// wait for interrupt    SSPIF = 0; // then clear it.    SSPBUF = 0; // address of register to write to     while(!SSPIF);//     SSPIF = 0; //    SSPBUF = 12; // clear screen     while(!SSPIF);//     SSPIF = 0; //    SSPBUF = 4; // cursor off     while(!SSPIF);//     SSPIF = 0; //         PEN = 1; // send stop bit    while(PEN); //}void cursor(char pos){    SEN = 1; // send start bit    while(SEN); // and wait for it to clear    SSPIF = 0;    SSPBUF = 0xc6;// LCD02 I2C address    while(!SSPIF);// wait for interrupt    SSPIF = 0; // then clear it.    SSPBUF = 0; // address of register to write to     while(!SSPIF);//     SSPIF = 0; //    SSPBUF = 2; // set cursor     while(!SSPIF);//     SSPIF = 0; //    SSPBUF = pos; //      while(!SSPIF);//     SSPIF = 0; //         PEN = 1; // send stop bit    while(PEN); //}void print(char *p){    SEN = 1; // send start bit    while(SEN); // and wait for it to clear    SSPIF = 0;    SSPBUF = 0xc6;// LCD02 I2C address    while(!SSPIF);// wait for interrupt    SSPIF = 0; // then clear it.    SSPBUF = 0; // address of register to write to     while(!SSPIF);//     SSPIF = 0; //    while(*p)     {        SSPBUF = *p++;// write the data         while(!SSPIF);//         SSPIF = 0; //     }    PEN = 1; // send stop bit    while(PEN); //}void setup(void){    unsigned long x;    TRISB = 0xfe; // RB0 (trig) is output    PORTB = 0xfe; // and starts low    TRISC = 0xff;    PORTC = 0xff;    SSPSTAT = 0x80;    SSPCON = 0x38;    SSPCON2 = 0x00;    SSPADD = 50; // SCL = 91khz with 20Mhz Osc    for(x=0; x<300000L; x++);// wait for LCD03 to initialise }
    
   

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