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      1 /*
      2  * Author: Jon Trulson <jtrulson (at) ics.com>
      3  * Copyright (c) 2014 Intel Corporation.
      4  *
      5  * Permission is hereby granted, free of charge, to any person obtaining
      6  * a copy of this software and associated documentation files (the
      7  * "Software"), to deal in the Software without restriction, including
      8  * without limitation the rights to use, copy, modify, merge, publish,
      9  * distribute, sublicense, and/or sell copies of the Software, and to
     10  * permit persons to whom the Software is furnished to do so, subject to
     11  * the following conditions:
     12  *
     13  * The above copyright notice and this permission notice shall be
     14  * included in all copies or substantial portions of the Software.
     15  *
     16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
     17  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
     18  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
     19  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
     20  * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
     21  * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
     22  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
     23  */
     24 
     25 #include <iostream>
     26 #include <string>
     27 #include <stdexcept>
     28 
     29 #include "mq303a.h"
     30 
     31 using namespace upm;
     32 
     33 MQ303A::MQ303A(int pin, int heaterPin)
     34 {
     35   if ( !(m_aio = mraa_aio_init(pin)) )
     36     {
     37       throw std::invalid_argument(std::string(__FUNCTION__) +
     38                                   ": mraa_aio_init() failed, invalid pin?");
     39       return;
     40     }
     41 
     42   if ( !(m_gpio = mraa_gpio_init(heaterPin)) )
     43     {
     44       throw std::invalid_argument(std::string(__FUNCTION__) +
     45                                   ": mraa_gpio_init() failed, invalid pin?");
     46       return;
     47     }
     48   mraa_gpio_dir(m_gpio, MRAA_GPIO_OUT);
     49 }
     50 
     51 MQ303A::~MQ303A()
     52 {
     53   heaterEnable(false);
     54   mraa_aio_close(m_aio);
     55   mraa_gpio_close(m_gpio);
     56 }
     57 
     58 int MQ303A::value()
     59 {
     60   return (1023 - mraa_aio_read(m_aio));
     61 }
     62 
     63 void MQ303A::heaterEnable(bool enable)
     64 {
     65   if (enable)
     66     mraa_gpio_write(m_gpio, 0);  // 0 turns on the heater
     67   else
     68     mraa_gpio_write(m_gpio, 1);  // 1 turns off the heater
     69 }
     70