odroid-temp/lib/odroid-temp.js

Read the temp sensor on Odroid

/*jslint node: true */
"use strict";
var fs = require("fs");
var util = require("util");
var EventEmitter = require("events").EventEmitter;
var os = require("os");

var TEMP = {};
TEMP.CELCIUS = "c";
TEMP.FARENHEIHT = "f";
// Poll frequency
TEMP.POLL = 2000;
// For kernel 3.0.x
TEMP.KERNEL_3_0 = "/sys/devices/platform/tmu/temperature";
// For kernel 3.8.x
TEMP.KERNEL_3_8 = "/sys/devices/virtual/thermal/thermal_zone0/temp";

function Temp(unit, poll) {
	this.oldtemp = -100;

	this.init = function() {
		var release = os.release();
		if (release.substr(0, 3) == "3.0") {
			this.mode = TEMP.KERNEL_3_0;
		} else {
			this.mode = TEMP.KERNEL_3_8;
		}
		if ("undefined" != unit) {
			this.unit = unit;
		} else {
			this.unit = TEMP.CELCIUS;
		}
		if ("undefined" != poll) {
			this.poll = TEMP.POLL;
		} else {
			this.poll = poll;
		}
		createListener.call(this);
	};

	this.read = function(cb) {
		var temp = this;
		fs.readFile(this.mode, "utf-8", function(err, data) {
			var value = 0;
			if (err !== null) {
				throw new Error("Failed to read " + temp.mode);
			} else {
				value = (data / 1000);
				if (temp.unit == TEMP.FARENHEIHT) {
					value = value * 1.8 + 32;
				}
				value = value.toFixed(2);
			}
			cb(err, value);
		});
	};

	EventEmitter.call(this);
	this.init();

	function createListener() {
		/* jshint validthis:true */
		var temp = this;
		setInterval(function() {
			temp.read(function(err, value) {
				if (err !== null) {
					throw new Error("Failed to read value after a change on "
							+ temp.mode);
				} else {
					if (value != temp.oldtemp) {
						temp.emit("change", value);
						temp.oldtemp = value;
					}
				}
			});
		}, temp.poll);
	}
}

util.inherits(Temp, EventEmitter);

exports.TEMP = TEMP;
module.exports = Temp;