Felipe dos Santos Neves / HCSR04

my version

Fork of HCSR04 by Awadh Al Shukaili

HCSR04.cpp@1:62f97e90a58c, 2017-11-18 (annotated)

Committer:
feupos
Date:
Sat Nov 18 18:27:18 2017 +0000
Revision:
1:62f97e90a58c
Parent:
0:0bda99bb39a4 
set to float

Who changed what in which revision?

UserRevisionLine numberNew contents of line
aralshukaili 0:0bda99bb39a4 1 #include "HCSR04.h"
aralshukaili 0:0bda99bb39a4 2 #include "mbed.h"
aralshukaili 0:0bda99bb39a4 3
aralshukaili 0:0bda99bb39a4 4
aralshukaili 0:0bda99bb39a4 5 HCSR04::HCSR04(PinName t, PinName e) : trig(t), echo(e) {}
aralshukaili 0:0bda99bb39a4 6
aralshukaili 0:0bda99bb39a4 7 // Trigger Echo
aralshukaili 0:0bda99bb39a4 8 // _______ _____________,,,,,,,,,
aralshukaili 0:0bda99bb39a4 9 // ____| 10us |_________| 150us-25ms, or 38ms if no obstacle
aralshukaili 0:0bda99bb39a4 10 //
aralshukaili 0:0bda99bb39a4 11
aralshukaili 0:0bda99bb39a4 12 //return echo duration in us (refer to digram above)
feupos 1:62f97e90a58c 13 float HCSR04::echo_duration() {
aralshukaili 0:0bda99bb39a4 14 timer.reset();
aralshukaili 0:0bda99bb39a4 15 trig = 0;
aralshukaili 0:0bda99bb39a4 16 wait_us(2);
aralshukaili 0:0bda99bb39a4 17 trig = 1;
aralshukaili 0:0bda99bb39a4 18 wait_us(10);
aralshukaili 0:0bda99bb39a4 19 trig = 0;
aralshukaili 0:0bda99bb39a4 20 while(echo == 0);
aralshukaili 0:0bda99bb39a4 21 timer.start();
aralshukaili 0:0bda99bb39a4 22 while(echo == 1);
aralshukaili 0:0bda99bb39a4 23 timer.stop();
aralshukaili 0:0bda99bb39a4 24 return timer.read_us();
aralshukaili 0:0bda99bb39a4 25 }
aralshukaili 0:0bda99bb39a4 26
aralshukaili 0:0bda99bb39a4 27 //return distance to nearest obstacle or returns -1
aralshukaili 0:0bda99bb39a4 28 //if no obstacle within range
aralshukaili 0:0bda99bb39a4 29 //set sys to cm or inch accordingly
feupos 1:62f97e90a58c 30 float HCSR04::distance(int sys){
aralshukaili 0:0bda99bb39a4 31 duration = echo_duration();
aralshukaili 0:0bda99bb39a4 32 if(duration > 30000)
aralshukaili 0:0bda99bb39a4 33 return -1;
aralshukaili 0:0bda99bb39a4 34 distacne_cm = duration /29 / 2 ;
aralshukaili 0:0bda99bb39a4 35 distance_inc = duration / 74 / 2;
aralshukaili 0:0bda99bb39a4 36 if (sys)
aralshukaili 0:0bda99bb39a4 37 return distacne_cm;
aralshukaili 0:0bda99bb39a4 38 else
aralshukaili 0:0bda99bb39a4 39 return distance_inc;
aralshukaili 0:0bda99bb39a4 40 }
aralshukaili 0:0bda99bb39a4 41