HCSR04.cpp

00001 /**
00002  * @author Nestor Pereira-Neto Team: SalvadorEngenharia
00003  *
00004  * @section LICENSE
00005  *
00006  * Copyright (c) 2010 ARM Limited
00007  *
00008  * Permission is hereby granted, free of charge, to any person obtaining a copy
00009  * of this software and associated documentation files (the "Software"), to deal
00010  * in the Software without restriction, including without limitation the rights
00011  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
00012  * copies of the Software, and to permit persons to whom the Software is
00013  * furnished to do so, subject to the following conditions:
00014  *
00015  * The above copyright notice and this permission notice shall be included in
00016  * all copies or substantial portions of the Software.
00017  *
00018  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
00019  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
00020  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
00021  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
00022  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
00023  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
00024  * THE SOFTWARE.
00025  *
00026  * @section DESCRIPTION
00027  *
00028  * Biblioteca para uso do sonar HC-SR04, possui rotinas para permitir medições 
00029  * de distências retornado valores em centímetros, polegadas ou o tempo 
00030  * percorrido pelo som (em microsegundos).
00031  * Esta biblioteca pode ser usada com qualquer pino do microcontrolador.
00032  */
00033 
00034 
00035 #include "HCSR04.h"
00036 #include "mbed.h"
00037 
00038 
00039 HCSR04::HCSR04(PinName trigger, PinName echo) : _t(trigger), _e(echo) {
00040     wait(0.1);
00041     }
00042 
00043 float HCSR04::getCm(void){
00044     distcm = readEcho()/58;
00045     return distcm;
00046     }
00047 
00048 float HCSR04::getIn(void){
00049     distin = readEcho()/148;
00050     return distin;
00051     }
00052 
00053 float HCSR04::readEcho(void){     
00054     _t=1;                       //Inicio do trigger
00055     wait_us(10);                //10us de pulso
00056     _t=0;                       //Fim do trigger
00057     while(!_e);
00058     _tempo.start();
00059     while(_e);
00060     tdist = _tempo.read_us();   //Leitura do tempo transcorrido 
00061     _tempo.stop();              //Paro o temporizador
00062     _tempo.reset();             //Reset para o próximo ciclo
00063     return tdist;
00064 }