ardupilot/libraries/AP_RangeFinder/AP_RangeFinder_SharpGP2Y.cpp

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// -*- tab-width: 4; Mode: C++; c-basic-offset: 3; indent-tabs-mode: t -*-
/*
AP_RangeFinder_SharpGP2Y.cpp - Arduino Library for Sharpe GP2Y0A02YK0F
infrared proximity sensor
Code by Jose Julio and Randy Mackay. DIYDrones.com
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
Sensor should be conected to one of the analog ports
Sparkfun URL: http://www.sparkfun.com/products/8958
datasheet: http://www.sparkfun.com/datasheets/Sensors/Infrared/gp2y0a02yk_e.pdf
Variables:
int raw_value : raw value from the sensor
int distance : distance in cm
int max_distance : maximum measurable distance (in cm)
int min_distance : minimum measurable distance (in cm)
Methods:
init(int analogPort) : Initialization of sensor
read() : read value from analog port
*/
// AVR LibC Includes
#include "WConstants.h"
#include "AP_RangeFinder_SharpGP2Y.h"
// Public Methods //////////////////////////////////////////////////////////////
void AP_RangeFinder_SharpGP2Y::init(int analogPort)
{
// local variables
int i;
// set the given analog port to an input
pinMode(analogPort, INPUT);
// initialise everything
_analogPort = analogPort;
max_distance = AP_RANGEFINDER_SHARPEGP2Y_MAX_DISTANCE;
min_distance = AP_RANGEFINDER_SHARPEGP2Y_MIN_DISTANCE;
// make first call to read to get initial distance
read();
// initialise history
for( i=0; i<AP_RANGEFINDER_NUM_AVERAGES; i++ )
_history[i] = distance;
}
// Read Sensor data
int AP_RangeFinder_SharpGP2Y::read()
{
// read raw sensor value and convert to distance
raw_value = analogRead(_analogPort);
if( raw_value == 0 )
distance = max_distance;
else
distance = constrain(14500/raw_value,min_distance,max_distance);
// return distance
return filter(distance);
}