upm/examples/javascript/mq7.js

/*jslint node:true, vars:true, bitwise:true, unparam:true */
/*jshint unused:true */
/*
 * Author: Jon Trulson <jtrulson@ics.com>
 * Copyright (c) 2015 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.
 */

var upmGAS = require("jsupm_gas");

// Attach gas sensor to Analog A0
var sensor = new upmGAS.MQ7(0);

var threshContext = new upmGAS.thresholdContext;
threshContext.averageReading = 0;
threshContext.runningAverage = 0;
threshContext.averagedOver = 2;

// Infinite loop, ends when script is cancelled
// Repeatedly, take a sample every 2 microseconds;
// find the average of 128 samples; and
// print a running graph of asteriskss as averages

while(1)
{
    var buffer = new upmGAS.uint16Array(128);
    var len = sensor.getSampledWindow(2, 128, buffer);
    if (len)
    {
        var thresh = sensor.findThreshold(threshContext, 30, buffer, len);
        sensor.printGraph(threshContext, 5);
        //if (thresh)
        //    console.log("Threshold is " + thresh);
    }
}

// Print message when exiting
process.on('SIGINT', function()
{
	console.log("Exiting...");
	process.exit(0);
});