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126 lines
3.1 KiB
C++
126 lines
3.1 KiB
C++
/*
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* Author: Jon Trulson <jtrulson@ics.com>
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* Copyright (c) 2016 Intel Corporation.
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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#include <iostream>
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#include "teams.hpp"
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using namespace upm;
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using namespace std;
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// for current loop reads that seems a little noisy, we average over
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// several aio reads.
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static const int maxSamples = 50;
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// conversion from celsius to fahrenheit
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static float c2f(float c)
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{
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return (c * (9.0 / 5.0) + 32.0);
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}
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TEAMS::TEAMS(int tPin, float rResistor, float aref) :
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m_aioTemp(tPin)
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{
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if (rResistor < 0.0)
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{
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throw std::out_of_range(std::string(__FUNCTION__) +
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": rResistor must be >= 0.0");
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}
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m_aResTemp = (1 << m_aioTemp.getBit());
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m_temperature = 0.0;
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m_aref = aref;
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m_rResistor = rResistor;
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m_connected = false;
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// this will only be non-zero when using a direct 4-20ma interface
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// like libelium
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m_rawMilliamps = 0.0;
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m_offset = 0.0;
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}
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TEAMS::~TEAMS()
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{
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}
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void TEAMS::update()
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{
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float milliamps = 0.0;
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int val = average(maxSamples);
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float volts = (float(val) * (m_aref / m_aResTemp));
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// valid temp range is 25.0 (35C - 10C), current loop range is 16ma
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// (20ma - 4ma)
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if (m_rResistor)
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{
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// direct 4-20 current loop interface
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milliamps = (volts / m_rResistor * 1000.0) + m_offset;
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m_rawMilliamps = milliamps;
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// subtract 0 (4ma) value
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milliamps -= 4.0;
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if (milliamps < 0.0) // not connected
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{
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milliamps = 0.0;
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m_connected = false;
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}
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else
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m_connected = true;
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m_temperature = (milliamps * (25.0 / 16.0)) + 10.0;
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}
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else
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{
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// normal analog read, already scaled to 0-5v, always connected
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m_temperature = ((volts / m_aref) * 25.0) + 10.0;
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m_connected = true;
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}
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}
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float TEAMS::getTemperature(bool fahrenheit)
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{
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if (fahrenheit)
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return c2f(m_temperature);
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else
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return m_temperature;
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}
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int TEAMS::average(int samples)
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{
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if (samples <= 0)
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samples = 1;
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int avg = 0;
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for (int i=0; i<samples; i++)
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avg += m_aioTemp.read();
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return (avg / samples);
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}
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