RangeFinder.cpp

00001 /* Copyright (c) 2012 Nick Ryder, University of Oxford
00002  * nick.ryder@physics.ox.ac.uk
00003  *
00004  *  MIT License
00005  *
00006  * Permission is hereby granted, free of charge, to any person obtaining a copy of this software 
00007  * and associated documentation files (the "Software"), to deal in the Software without restriction, 
00008  * including without limitation the rights to use, copy, modify, merge, publish, distribute, 
00009  * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is 
00010  * furnished to do so, subject to the following conditions:
00011  *
00012  * The above copyright notice and this permission notice shall be included in all copies or 
00013  * substantial portions of the Software.
00014  *
00015  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING 
00016  * BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 
00017  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, 
00018  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 
00019  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
00020  */
00021  
00022  
00023  #include "RangeFinder.h"
00024 
00025 RangeFinder::RangeFinder(PinName pin, int pulsetime, float scale, int time):
00026     pio(pin), scale(scale), pulsetime(pulsetime), timeout(time)  {
00027 }
00028 
00029 RangeFinder::~RangeFinder() {
00030 }
00031 
00032 float RangeFinder::read_m()  {
00033     pio.write_us(1, pulsetime);
00034     float t = (float) pio.read_high_us(timeout);
00035     if (t == -1.0)   {
00036         return -1.0;
00037     }
00038     return t / scale;
00039 }
00040