first commit

Software/NodeJS/libs/sensors/dustDigitalSensor.js

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+// TODO: call disable function on exit
+var DigitalSensor = require('./base/digitalSensor')
+var commands = require('../commands')
+var helpers = require('./helpers')
+
+function DustDigitalSensor(pin) {
+  DigitalSensor.apply(this, Array.prototype.slice.call(arguments))
+  this.results = new Array()
+}
+DustDigitalSensor.prototype = new DigitalSensor()
+
+DustDigitalSensor.prototype.read = function () {
+  var write = this.board.writeBytes(commands.dustSensorRead.concat([this.pin, commands.unused, commands.unused]))
+  if (write) {
+    this.board.wait(200)
+    var bytes = this.board.readBytes()
+    //console.log(bytes[0] + ' ' + bytes[1] + ' ' + bytes[2] + ' ' + bytes[3])
+    if (bytes instanceof Buffer && bytes[0] != 0)
+      return [bytes[0], (bytes[3] * 256 * 256 + bytes[2] * 256 + bytes[1])]
+    else
+      return false
+  } else {
+    return false
+  }
+}
+DustDigitalSensor.prototype.enable = function () {
+  var write = this.board.writeBytes(commands.dustSensorEn.concat([commands.unused, commands.unused, commands.unused]))
+  if (write) {
+    this.board.wait(200)
+    return true
+  } else {
+    return false
+  }
+}
+DustDigitalSensor.prototype.disable = function () {
+  var write = this.board.writeBytes(commands.dustSensorDis.concat([commands.unused, commands.unused, commands.unused]))
+  if (write) {
+    this.board.wait(200)
+    return true
+  } else {
+    return false
+  }
+}
+
+DustDigitalSensor.prototype.start = function () {
+    if (!this.enable())
+        throw new Error('cannot enable dust sensor')
+    this.enable()
+    setInterval(loop.bind(this), 30 * 1000) //every 30 seconds
+}
+
+DustDigitalSensor.prototype.stop = function () {
+    this.disable()
+    clearInterval(loop)
+}
+
+function loop() {
+    let currentResult = this.read()
+    this.results.push(currentResult[1])
+}
+
+DustDigitalSensor.prototype.readAvgMax = function () {
+
+    if (this.results.length === 0) return {
+        avg: helpers.NOT_AVAILABLE,
+        max: helpers.NOT_AVAILABLE
+    };
+
+    let sum = this.results.reduce((acc, cur) => acc + cur, 0)
+    let avg = sum / this.results.length
+
+    let max = this.results.reduce(function (a, b) {
+        return Math.max(a, b)
+    });
+
+    //reset the array
+    this.results = new Array()
+
+    return {
+        avg: helpers.round(avg, 2),
+        max: helpers.round(max, 2)
+    };
+}
+
+module.exports = DustDigitalSensor