di-sensors/lib/sensors/DHT.js

Drivers and examples for using DI_Sensors in Node.js

'use strict';

var _createClass = function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; }();

function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }

// https://www.dexterindustries.com/GoPiGo/
// https://github.com/DexterInd/DI_Sensors
//
// Copyright (c) 2017 Dexter Industries
// Released under the MIT license (http://choosealicense.com/licenses/mit/).
// For more information see https://github.com/DexterInd/GoPiGo3/blob/master/LICENSE.md

var DHTDevice = require('dht-drivers');

var DHT = function () {
    function DHT() {
        var moduleType = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : DHT.DHT11;
        var scale = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : DHT.SCALE_C;

        _classCallCheck(this, DHT);

        this.moduleType = moduleType;
        this.scale = scale;
    }

    _createClass(DHT, [{
        key: 'convertCtoF',
        value: function convertCtoF(temp) {
            return temp * 1.8 + 32;
        }
    }, {
        key: 'convertFtoC',
        value: function convertFtoC(temp) {
            return (temp - 32) / 1.8;
        }
    }, {
        key: 'getHeatIndex',
        value: function getHeatIndex(temp, hum, scale) {
            // http://www.wpc.ncep.noaa.gov/html/heatindex_equation.shtml
            var needsConversion = typeof scale === 'undefined' || scale === DHT.SCALE_C;

            temp = needsConversion ? this.convertCtoF(temp) : temp;

            // Steadman's result
            var heatIndex = 0.5 * (temp + 61 + (temp - 68) * 1.2 + hum * 0.094);

            // regression equation of Rothfusz is appropriate
            if (temp >= 80) {
                var heatIndexBase = -42.379 + 2.04901523 * temp + 10.14333127 * hum + -0.22475541 * temp * hum + -0.00683783 * temp * temp + -0.05481717 * hum * hum + 0.00122874 * temp * temp * hum + 0.00085282 * temp * hum * hum + -0.00000199 * temp * temp * hum * hum;
                // adjustment
                if (hum < 13 && temp <= 112) {
                    heatIndex = heatIndexBase - (13 - hum) / 4 * Math.sqrt((17 - Math.abs(temp - 95)) / 17);
                } else if (hum > 85 && temp <= 87) {
                    heatIndex = heatIndexBase + (hum - 85) / 10 * ((87 - temp) / 5);
                } else {
                    heatIndex = heatIndexBase;
                }
            }

            return needsConversion ? this.convertFtoC(heatIndex) : heatIndex;
        }
    }, {
        key: 'read',
        value: function read() {
            // 2 = RapsberryPi platform ID
            // 15 = Serial PIN
            var data = DHTDevice.read(2, this.moduleType, 15);
            var temp = +Number(parseFloat(data.temperature).toFixed(2));
            var hum = +Number(parseFloat(data.humidity).toFixed(2));

            if (this.scale === DHT.SCALE_F) {
                temp = this.convertCtoF(temp);
            }

            var heatIndex = +Number(parseFloat(this.getHeatIndex(temp, hum, this.scale)).toFixed(2));
            return [temp, hum, heatIndex];
        }
    }]);

    return DHT;
}();

DHT.DHT11 = 11;
DHT.DHT22 = 22;
DHT.AM2302 = 22;
DHT.SCALE_C = 'c';
DHT.SCALE_F = 'f';


module.exports = DHT;