Clark Scheff / Ping

Library for interfacing with the Parallax Ping))) sensor.

Dependencies:   FPointer

ping.cpp@3:0c337c262d84, 2014-07-28 (annotated)

Committer:
d34d
Date:
Mon Jul 28 00:16:34 2014 +0000
Revision:
3:0c337c262d84
Parent:
1:72fbcb01291d
Child:
5:cbe07c09c64c
Cleaned up timing of the pulse and added helper methods to convert time in uS to distance traveled in centimeters or inches.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
d34d 0:99ee7c741e9d 1 #include "ping.h"
d34d 0:99ee7c741e9d 2
d34d 3:0c337c262d84 3 Ping::Ping(PinName signalPin) : mSignalIo(signalPin), mEvent(signalPin),
d34d 0:99ee7c741e9d 4 mBusy(0), mValid(0), mContinuous(0), mTimer(), mRawReading(0) {
d34d 0:99ee7c741e9d 5 mEvent.rise(this, &Ping::start);
d34d 0:99ee7c741e9d 6 mEvent.fall(this, &Ping::stop);
d34d 0:99ee7c741e9d 7 }
d34d 0:99ee7c741e9d 8
d34d 0:99ee7c741e9d 9 bool Ping::startReading() {
d34d 0:99ee7c741e9d 10 return this->startReading(false);
d34d 0:99ee7c741e9d 11 }
d34d 0:99ee7c741e9d 12
d34d 0:99ee7c741e9d 13 bool Ping::startReading(bool continuous) {
d34d 0:99ee7c741e9d 14 mContinuous = continuous;
d34d 0:99ee7c741e9d 15 if (mBusy) return false;
d34d 0:99ee7c741e9d 16
d34d 0:99ee7c741e9d 17 mSignalIo.output();
d34d 3:0c337c262d84 18 mSignalIo.write(0);
d34d 3:0c337c262d84 19 wait_us(3);
d34d 3:0c337c262d84 20 mSignalIo.write(1);
d34d 3:0c337c262d84 21 wait_us(3);
d34d 3:0c337c262d84 22 mSignalIo.write(0);
d34d 0:99ee7c741e9d 23 mSignalIo.input();
d34d 0:99ee7c741e9d 24
d34d 0:99ee7c741e9d 25 return true;
d34d 0:99ee7c741e9d 26 }
d34d 0:99ee7c741e9d 27
d34d 0:99ee7c741e9d 28 void Ping::start() {
d34d 0:99ee7c741e9d 29 mBusy = true;
d34d 0:99ee7c741e9d 30 mValid = false;
d34d 3:0c337c262d84 31 mTimer.reset();
d34d 0:99ee7c741e9d 32 mTimer.start();
d34d 0:99ee7c741e9d 33 }
d34d 0:99ee7c741e9d 34
d34d 0:99ee7c741e9d 35 void Ping::stop() {
d34d 0:99ee7c741e9d 36 mBusy = false;
d34d 0:99ee7c741e9d 37 mValid = true;
d34d 0:99ee7c741e9d 38 // The time it takes is for a round trip. We divide by two to get the time for one way.
d34d 3:0c337c262d84 39 mRawReading = mTimer.read_us() >> 1;
d34d 0:99ee7c741e9d 40 mTimer.stop();
d34d 0:99ee7c741e9d 41 mCallback.call(mRawReading);
d34d 1:72fbcb01291d 42 if (mContinuous) mMeasureDelayTicker.attach_us(this, &Ping::nextMeasurement, 5000);
d34d 1:72fbcb01291d 43 }
d34d 1:72fbcb01291d 44
d34d 1:72fbcb01291d 45 void Ping::nextMeasurement() {
d34d 1:72fbcb01291d 46 mMeasureDelayTicker.detach();
d34d 1:72fbcb01291d 47 this->startReading(mContinuous);
d34d 0:99ee7c741e9d 48 }