超声波模块SRF05

////////////////////////////////////////////////////////////////////////////////

//

//     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 <pic.h>

#include <stdio.h>

 

__CONFIG(0x3b32);





#define trig RB0

#define echo RB1





void clrscn(void); // prototypes

void cursor(char pos);

void print(char *p);

void setup(void);

unsigned int get_srf04(void);





char s[21]; // buffer used to hold text to print





void 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

}