fe318a78d2
Implement a single source file for the following:
* mq2: H2/LPG/CH4/CO/alcohol/smoke/propane/etc
* mq3: Alcohol/benzine/CH4/hexane/LPG/CO
* mq4: CNG (mostly methane)
* mq5: H2/LPG/CH4/CO/alcohol
* mq6: LPG (mostly propane/butane)
* mq7: CO
* mq8: H
* mq9: CO/CH4/LPG
The documentation for these sensors notes that they do not read an exact
gas concentration. Some of the sensors have examples for how to
calibrate with a 'clean air environment' for outputing ppm, but this is
not the case for all mqx sensors. Because of this, the output can be
read as a normalized output (0.0->1.0), raw volts (normalized * aRef),
or a scaled/offset voltage.
Signed-off-by: Noel Eck <noel.eck@intel.com>
99 lines
2.7 KiB
C++
99 lines
2.7 KiB
C++
/*
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* Author: Brendan Le Foll <brendan.le.foll@intel.com>
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* Copyright (c) 2014 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 <unistd.h>
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#include <stdlib.h>
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#include <functional>
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#include <string.h>
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#include <stdexcept>
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#include "gas.hpp"
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using namespace upm;
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Gas::Gas(int gasPin) : m_aio(gasPin) {
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}
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Gas::~Gas() {
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}
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int
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Gas::getSampledWindow (unsigned int freqMS, int numberOfSamples,
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uint16_t * buffer) {
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int sampleIdx = 0;
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// must have freq
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if (!freqMS) {
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return 0;
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}
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// too many samples
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if (numberOfSamples > 0xFFFFFF) {
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return 0;
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}
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while (sampleIdx < numberOfSamples) {
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buffer[sampleIdx++] = getSample();
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usleep(freqMS * 1000);
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}
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return sampleIdx;
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}
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int
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Gas::findThreshold (thresholdContext* ctx, unsigned int threshold,
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uint16_t * buffer, int len) {
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long sum = 0;
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for (int i = 0; i < len; i++) {
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sum += buffer[i];
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}
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ctx->averageReading = sum / len;
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ctx->runningAverage = (((ctx->averagedOver-1) * ctx->runningAverage) + ctx->averageReading) / ctx->averagedOver;
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if (ctx->runningAverage > threshold) {
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return ctx->runningAverage;
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} else {
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return 0;
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}
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}
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int
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Gas::getSampledData (thresholdContext* ctx) {
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return ctx->runningAverage;
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}
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int
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Gas::getSample () {
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return m_aio.read();
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}
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void
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Gas::printGraph (thresholdContext* ctx, uint8_t resolution) {
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std::cout << "(" << ctx->runningAverage << ") | ";
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for (int i = 0; i < ctx->runningAverage / resolution; i++)
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std::cout << "*";
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std::cout << std::endl;
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}
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