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

Committer:
tbjazic
Date:
2016-12-10
Revision:
6:cf3e4e307d15
Parent:
4:aae70f15357f

File content as of revision 6:cf3e4e307d15:

#include "mbed.h"
#include "HCSR04.h"

HCSR04::HCSR04(PinName echoPin, PinName triggerPin) : echo(echoPin), trigger(triggerPin) {
    init();
}

void HCSR04::init() {
    distance = -1;      // initial distance
    minDistance = 2;
    maxDistance = 400;
    newDataReady = timerStarted = false;
}

void HCSR04::startTimer() {
    if (!timerStarted) {
        timer.start(); // start the timer
        timerStarted = true;
        echoTimeout.attach_us(this, &HCSR04::stopTimer, 25000); // in case echo fall does not occur
        echo.fall(this, &HCSR04::stopTimer);
        echo.rise(NULL);
    }
}

void HCSR04::stopTimer() {
    timer.stop(); // stop the timer
    if (timerStarted) {
        distance = timer.read() * 1e6 / 58;
        if (distance < minDistance)
            distance = minDistance;
        if (distance > maxDistance)
            distance = maxDistance;
        newDataReady = true;
    }
    timer.reset();
    timerStarted = false;
    echoTimeout.detach();
    echo.fall(NULL);
}

void HCSR04::turnOffTrigger() {
    trigger = 0; 
}

void HCSR04::startMeasurement() {
    trigger = 1;
    triggerTimeout.attach_us(this, &HCSR04::turnOffTrigger, 10);
    echo.rise(this, &HCSR04::startTimer);
    newDataReady = false;
}

float HCSR04::getDistance_cm() {
    newDataReady = false;
    return distance;
}

float HCSR04::getDistance_mm() {
    newDataReady = false;
    return distance * 10;
}

bool HCSR04::isNewDataReady() {
    return newDataReady;
}

void HCSR04::setRanges(float minRange, float maxRange) {
    if (minRange < maxRange) {
        if (minRange >= 2 && minRange < 400) // bug from revs. 4 and 5 corrected
            minDistance = minRange;
        if (maxRange <= 400)
            maxDistance = maxRange;
    }
}

float HCSR04::getMinRange() {
    return minDistance;
}

float HCSR04::getMaxRange() {
    return maxDistance;
}