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      1 /*
      2  * Author: Jon Trulson <jtrulson (at) ics.com>
      3  * Copyright (c) 2015 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 #pragma once
     25 
     26 #include <string>
     27 #include <mraa/aio.h>
     28 
     29 namespace upm {
     30 
     31   /**
     32    * @brief OTP538U IR Temperature Sensor library
     33    * @defgroup otp538u libupm-otp538u
     34    * @ingroup seeed analog light hak
     35    */
     36   /**
     37    * @library otp538u
     38    * @sensor otp538u
     39    * @comname OTP538U IR Temperature Sensor
     40    * @altname Grove IR Temperature Sensor
     41    * @type light
     42    * @man generic
     43    * @con analog
     44    * @kit hak
     45    *
     46    * @brief API for the OTP538U IR Temperature Sensor
     47    *
     48    * UPM module for the OTP538U IR temperature sensor
     49    *
     50    * This module was tested with the Grove IR non-contact temperature
     51    * sensor.
     52    *
     53    * The sensor provides 2 analog outputs: one for the thermistor
     54    * that measures the ambient temperature, and the other for the thermopile
     55    * that measures the object temperature.
     56    *
     57    * Much of the code depends on analyzing Seeed Studio* examples
     58    * and the circuit design. As a result, there are several 'magic'
     59    * numbers derived from their circuit design. These values are used
     60    * by default.
     61    *
     62    * The tables used came from the "538U VT
     63    * Table__20_200(v1.3).pdf" and "538RT_table.pdf" datasheets.
     64    *
     65    * These tables assume the object to be measured is 9 cm (3.54
     66    * inches) from the sensor.
     67    *
     68    * @image html otp538u.jpg
     69    * @snippet otp538u.cxx Interesting
     70    */
     71   class OTP538U {
     72   public:
     73     /**
     74      * OTP538U constructor
     75      *
     76      * @param pinA Analog pin to use for the ambient temperature
     77      * @param pinO Analog pin to use for the object temperature
     78      * @param aref Analog reference voltage; default is 5.0 V
     79      */
     80     OTP538U(int pinA, int pinO, float aref = 5.0);
     81 
     82     /**
     83      * OTP538U destructor
     84      */
     85     ~OTP538U();
     86 
     87     /**
     88      * Gets the ambient temperature in Celsius
     89      *
     90      * @return Ambient temperature
     91      */
     92     float ambientTemperature();
     93 
     94     /**
     95      * Gets the object temperature in Celsius
     96      *
     97      * @return Object temperature
     98      */
     99     float objectTemperature();
    100 
    101     /**
    102      * Sets the offset voltage
    103      *
    104      * The Seeed Studio wiki gives an example of calibrating the sensor
    105      * and calculating the offset voltage to apply. Currently, the
    106      * default value is set, but you can use the function to set one
    107      * of your own.
    108      *
    109      * @param vOffset Desired offset voltage
    110      */
    111     void setVoltageOffset(float vOffset) { m_offsetVoltage = vOffset; };
    112 
    113     /**
    114      * Sets the output resistance value
    115      *
    116      * The Seeed Studio wiki example uses a value of 2,000,000 in one of
    117      * the equations used to calculate voltage. The value is the
    118      * resistance of a resistor they use in the output stage of their
    119      * SIG2 output. This was 'decoded' by looking at the EAGLE* files
    120      * containing their schematics for this device.
    121      *
    122      * @param outResistance Value of the output resistor; default is 2M Ohm
    123      */
    124     void setOutputResistence(int outResistance) {
    125       m_vResistance = outResistance; };
    126 
    127     /**
    128      * Sets the reference voltage of the internal Seeed Studio voltage
    129      * regulator on the sensor board.
    130      *
    131      * The Seeed Studio wiki example uses a value of 2.5 in one of the
    132      * equations used to calculate the resistance of the ambient
    133      * thermistor. The value is the voltage of an internal voltage
    134      * regulator used on the sensor board. This was 'decoded' by
    135      * looking at the EAGLE files containing their schematics for this
    136      * device.
    137      *
    138      * @param vref Reference voltage of the internal sensor; default is 2.5 V
    139      */
    140     void setVRef(float vref) { m_vref = vref; };
    141 
    142 
    143   private:
    144     float m_vref;
    145     float m_aref;
    146     int m_vResistance;
    147     float m_offsetVoltage;
    148     int m_adcResolution;
    149     mraa_aio_context m_aioA;
    150     mraa_aio_context m_aioO;
    151   };
    152 }
    153 
    154 
    155