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