Temperature Monitoring with Intel Edison and ARTIK Cloud

/*jslint node:true,vars:true,bitwise:true,unparam:true */

/*jshint unused:true */

/*
The Local Temperature Node.js sample application distributed within Intel® XDK IoT Edition under the IoT with Node.js Projects project creation option showcases how to read analog data from a Grover Starter Kit Plus – IoT Intel® Edition Temperature Sensor, start a web server and communicate wirelessly using WebSockets.

MRAA - Low Level Skeleton Library for Communication on GNU/Linux platforms
Library in C/C++ to interface with Galileo & other Intel platforms, in a structured and sane API with port nanmes/numbering that match boards & with bindings to javascript & python.

Steps for installing MRAA & UPM Library on Intel IoT Platform with IoTDevKit Linux* image
Using a ssh client: 
1. echo "src maa-upm http://iotdk.intel.com/repos/1.1/intelgalactic" > /etc/opkg/intel-iotdk.conf
2. opkg update
3. opkg upgrade

Article: https://software.intel.com/en-us/html5/articles/iot-local-temperature-nodejs-and-html5-samples
*/

var webSocketUrl = "wss://api.artik.cloud/v1.1/websocket?ack=true";
var device_id = "your_device_id";
var device_token = "your_device_token";

var isWebSocketReady = false;
var ws = null;

var WebSocket = require('ws');

/**
 * Gets the current time in millis
 */
function getTimeMillis(){
    return parseInt(Date.now().toString());
}


/**
 * Create a /websocket device channel connection 
 */
function start() {
    //Create the websocket connection
    isWebSocketReady = false;
    ws = new WebSocket(webSocketUrl);
    ws.on('open', function() {
        console.log("Websocket connection is open ....");
        register();
    });
    ws.on('message', function(data, flags) {
        console.log("Received message: " + data + '\n');
    });
    ws.on('close', function() {
        console.log("Websocket connection is closed ....");
    });
}

/**
 * Sends a register message to the websocket and starts the message flooder
 */
function register(){
    console.log("Registering device on the websocket connection");
    try{
        var registerMessage = '{"type":"register", "sdid":"'+device_id+'", "Authorization":"bearer '+device_token+'", "cid":"'+getTimeMillis()+'"}';
        console.log('Sending register message ' + registerMessage + '\n');
        ws.send(registerMessage, {mask: true});
        isWebSocketReady = true;
    }
    catch (e) {
        console.error('Failed to register messages. Error in registering message: ' + e.toString());
    }   
}

/**
 * Send one message to ARTIK Cloud
 */
function sendData(temp){
    try{
        ts = ', "ts": '+getTimeMillis();
        var data = {
            "currentTemp": temp
        };
        var payload = '{"sdid":"'+device_id+'"'+ts+', "data": '+JSON.stringify(data)+', "cid":"'+getTimeMillis()+'"}';
        console.log('Sending payload ' + payload);
        ws.send(payload, {mask: true});
    } catch (e) {
        console.error('Error in sending a message: ' + e.toString());
    }   
}


var B = 3975;
var mraa = require("mraa");

//GROVE Kit A0 Connector --> Aio(0)
var myAnalogPin = new mraa.Aio(0);

/*
Function: startSensorWatch(socket)
Parameters: socket - client communication channel
Description: Read Temperature Sensor and send temperature in degrees of Fahrenheit every 4 seconds
*/
function startSensorWatch(socket) {
    'use strict';
    setInterval(function () {
        var a = myAnalogPin.read();
        console.log("Analog Pin (A0) Output: " + a);
        //console.log("Checking....");
        
        var resistance = (1023 - a) * 10000 / a; //get the resistance of the sensor;
        //console.log("Resistance: "+resistance);
        var celsius_temperature = 1 / (Math.log(resistance / 10000) / B + 1 / 298.15) - 273.15;//convert to temperature via datasheet ;
        //console.log("Celsius Temperature "+celsius_temperature); 
        var fahrenheit_temperature = (celsius_temperature * (9 / 5)) + 32;
        console.log("Fahrenheit Temperature: " + fahrenheit_temperature);
        socket.emit("message", fahrenheit_temperature);
        
        sendData(fahrenheit_temperature);
        
    }, 15000);
}

console.log("Sample Reading Grove Kit Temperature Sensor");

//Create Socket.io server
var http = require('http');
var app = http.createServer(function (req, res) {
    'use strict';
    res.writeHead(200, {'Content-Type': 'text/plain'});
    res.end('<h1>Hello world from Intel IoT platform!</h1>');
}).listen(1337);
var io = require('socket.io')(app);

start();

//Attach a 'connection' event handler to the server
io.on('connection', function (socket) {
    'use strict';
    console.log('a user connected');
    //Emits an event along with a message
    socket.emit('connected', 'Welcome');

    //Start watching Sensors connected to Galileo board
    startSensorWatch(socket);

    //Attach a 'disconnect' event handler to the socket
    socket.on('disconnect', function () {
        console.log('user disconnected');
    });
});