TVZ Mechatronics Team / HCSR04

A distance measurement class using ultrasonic sensor HC-SR04.

Dependents:   Esercitazione4_4 HC-SR04 Group10_slave Oled_Gus ... more

The purpose of this library is to encourage students to develope their own classes. Instructions how to follow the development of this library for ultrasonic distance measurement are given here.

HCSR04.cpp@6:cf3e4e307d15, 2016-12-10 (annotated)

Committer:
tbjazic
Date:
Sat Dec 10 08:26:18 2016 +0000
Revision:
6:cf3e4e307d15
Parent:
4:aae70f15357f 
Filtering with Ticker object corrected.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
tbjazic 0:8871082486ac 1 #include "mbed.h"
tbjazic 0:8871082486ac 2 #include "HCSR04.h"
tbjazic 0:8871082486ac 3
tbjazic 0:8871082486ac 4 HCSR04::HCSR04(PinName echoPin, PinName triggerPin) : echo(echoPin), trigger(triggerPin) {
tbjazic 0:8871082486ac 5 init();
tbjazic 0:8871082486ac 6 }
tbjazic 0:8871082486ac 7
tbjazic 0:8871082486ac 8 void HCSR04::init() {
tbjazic 3:9a7899cf5e3a 9 distance = -1; // initial distance
tbjazic 4:aae70f15357f 10 minDistance = 2;
tbjazic 3:9a7899cf5e3a 11 maxDistance = 400;
tbjazic 6:cf3e4e307d15 12 newDataReady = timerStarted = false;
tbjazic 0:8871082486ac 13 }
tbjazic 0:8871082486ac 14
tbjazic 0:8871082486ac 15 void HCSR04::startTimer() {
tbjazic 6:cf3e4e307d15 16 if (!timerStarted) {
tbjazic 6:cf3e4e307d15 17 timer.start(); // start the timer
tbjazic 6:cf3e4e307d15 18 timerStarted = true;
tbjazic 6:cf3e4e307d15 19 echoTimeout.attach_us(this, &HCSR04::stopTimer, 25000); // in case echo fall does not occur
tbjazic 6:cf3e4e307d15 20 echo.fall(this, &HCSR04::stopTimer);
tbjazic 6:cf3e4e307d15 21 echo.rise(NULL);
tbjazic 6:cf3e4e307d15 22 }
tbjazic 0:8871082486ac 23 }
tbjazic 0:8871082486ac 24
tbjazic 0:8871082486ac 25 void HCSR04::stopTimer() {
tbjazic 0:8871082486ac 26 timer.stop(); // stop the timer
tbjazic 6:cf3e4e307d15 27 if (timerStarted) {
tbjazic 6:cf3e4e307d15 28 distance = timer.read() * 1e6 / 58;
tbjazic 6:cf3e4e307d15 29 if (distance < minDistance)
tbjazic 6:cf3e4e307d15 30 distance = minDistance;
tbjazic 6:cf3e4e307d15 31 if (distance > maxDistance)
tbjazic 6:cf3e4e307d15 32 distance = maxDistance;
tbjazic 6:cf3e4e307d15 33 newDataReady = true;
tbjazic 6:cf3e4e307d15 34 }
tbjazic 6:cf3e4e307d15 35 timer.reset();
tbjazic 6:cf3e4e307d15 36 timerStarted = false;
tbjazic 6:cf3e4e307d15 37 echoTimeout.detach();
tbjazic 6:cf3e4e307d15 38 echo.fall(NULL);
tbjazic 6:cf3e4e307d15 39 }
tbjazic 6:cf3e4e307d15 40
tbjazic 6:cf3e4e307d15 41 void HCSR04::turnOffTrigger() {
tbjazic 6:cf3e4e307d15 42 trigger = 0;
tbjazic 0:8871082486ac 43 }
tbjazic 0:8871082486ac 44
tbjazic 0:8871082486ac 45 void HCSR04::startMeasurement() {
tbjazic 0:8871082486ac 46 trigger = 1;
tbjazic 6:cf3e4e307d15 47 triggerTimeout.attach_us(this, &HCSR04::turnOffTrigger, 10);
tbjazic 6:cf3e4e307d15 48 echo.rise(this, &HCSR04::startTimer);
tbjazic 6:cf3e4e307d15 49 newDataReady = false;
tbjazic 0:8871082486ac 50 }
tbjazic 0:8871082486ac 51
tbjazic 0:8871082486ac 52 float HCSR04::getDistance_cm() {
tbjazic 6:cf3e4e307d15 53 newDataReady = false;
tbjazic 0:8871082486ac 54 return distance;
tbjazic 4:aae70f15357f 55 }
tbjazic 4:aae70f15357f 56
tbjazic 4:aae70f15357f 57 float HCSR04::getDistance_mm() {
tbjazic 6:cf3e4e307d15 58 newDataReady = false;
tbjazic 4:aae70f15357f 59 return distance * 10;
tbjazic 4:aae70f15357f 60 }
tbjazic 4:aae70f15357f 61
tbjazic 6:cf3e4e307d15 62 bool HCSR04::isNewDataReady() {
tbjazic 6:cf3e4e307d15 63 return newDataReady;
tbjazic 6:cf3e4e307d15 64 }
tbjazic 6:cf3e4e307d15 65
tbjazic 4:aae70f15357f 66 void HCSR04::setRanges(float minRange, float maxRange) {
tbjazic 4:aae70f15357f 67 if (minRange < maxRange) {
tbjazic 6:cf3e4e307d15 68 if (minRange >= 2 && minRange < 400) // bug from revs. 4 and 5 corrected
tbjazic 4:aae70f15357f 69 minDistance = minRange;
tbjazic 4:aae70f15357f 70 if (maxRange <= 400)
tbjazic 4:aae70f15357f 71 maxDistance = maxRange;
tbjazic 4:aae70f15357f 72 }
tbjazic 4:aae70f15357f 73 }
tbjazic 4:aae70f15357f 74
tbjazic 4:aae70f15357f 75 float HCSR04::getMinRange() {
tbjazic 4:aae70f15357f 76 return minDistance;
tbjazic 4:aae70f15357f 77 }
tbjazic 4:aae70f15357f 78
tbjazic 4:aae70f15357f 79 float HCSR04::getMaxRange() {
tbjazic 4:aae70f15357f 80 return maxDistance;
tbjazic 0:8871082486ac 81 }