Hight_Temp.cpp

/*
    High_Temp.cpp

    2014 Copyright (c) Seeed Technology Inc.  All right reserved.

    Loovee
    2013-4-14

    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.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/

#include <Arduino.h>
#include "High_Temp.h"


const float VOL_OFFSET = 350;                       // offset voltage, mv
const float AMP_AV     = 54.16;                     // Av of amplifier


const float Var_VtoT_K[3][10] = {
    {
        0, 2.5173462e1, -1.1662878, -1.0833638, -8.9773540 / 1e1, -3.7342377 / 1e1,
        -8.6632643 / 1e2, -1.0450598 / 1e2, -5.1920577 / 1e4
    },
    {
        0, 2.508355e1, 7.860106 / 1e2, -2.503131 / 1e1, 8.315270 / 1e2,
        -1.228034 / 1e2, 9.804036 / 1e4, -4.413030 / 1e5, 1.057734 / 1e6, -1.052755 / 1e8
    },
    {
        -1.318058e2, 4.830222e1, -1.646031, 5.464731 / 1e2, -9.650715 / 1e4,
            8.802193 / 1e6, -3.110810 / 1e8
        }
};


HighTemp::HighTemp(int _pinTmp, int _pinThmc) {

    pinRoomTmp = _pinTmp;
    pinThmc    = _pinThmc;


}

void HighTemp::begin() {

    tempRoom   = getRoomTmp();

    Serial.print("tempRoom = ");
    Serial.println(tempRoom);

    delay(10);
    Serial.print("pinRoomTmp = "); Serial.println(pinRoomTmp);

    delay(10);
    Serial.print("pinThmc = "); Serial.println(pinThmc);
}

float HighTemp::getThmc() {
    float vol  = getThmcVol();

    tempThmc = K_VtoT(vol) + tempRoom;

    return tempThmc;
}


int HighTemp::getAnalog(int pin) {
    long sum = 0;

    for (int i = 0; i < 32; i++) {
        sum += analogRead(pin);
    }

    return ((sum >> 5));                                            // 3.3V supply
}


float HighTemp::getRoomTmp() {
    int a = getAnalog(pinRoomTmp) * 50 / 33;                            // 3.3V supply
    float resistance = (float)(1023 - a) * 10000 / a;                   // get the resistance of the sensor;
    float temperature = 1 / (log(resistance / 10000) / 3975 + 1 / 298.15) -
                        273.15; // convert to temperature via datasheet ;


    Serial.print("a = "); Serial.println(a);
    Serial.print("resistance = "); Serial.println(resistance);
    // Serial.print("temperature = ");Serial.println(temperature);

    tempRoom = temperature;
    return temperature;
}


float HighTemp::getThmcVol() {                                           // get voltage of thmc in mV
    float vout = (float)getAnalog(pinThmc) / 1023.0 * 5.0 * 1000;
    float vin  = (vout - VOL_OFFSET) / AMP_AV;
    return (vin);
}


float HighTemp::K_VtoT(float mV) {
    int i = 0;
    float value = 0;

    if (mV >= -6.478 && mV < 0) {
        value = Var_VtoT_K[0][8];

        for (i = 8; i > 0; i--) {
            value = mV * value + Var_VtoT_K[0][i - 1];
        }
    } else if (mV >= 0 && mV < 20.644) {
        value = Var_VtoT_K[1][9];

        for (i = 9; i > 0; i--) {
            value = mV * value + Var_VtoT_K[1][i - 1];
        }
    } else if (mV >= 20.644 && mV <= 54.900) {
        value = Var_VtoT_K[2][6];

        for (i = 6; i > 0; i--) {
            value = mV * value + Var_VtoT_K[2][i - 1];
        }
    }

    return value;
}