var http = require("http").createServer(handler); // on req - hand

var io = require("socket.io").listen(http); // socket library

var fs = require("fs"); // variable for file system for providing html

var firmata = require("firmata");

console.log("Starting the code");

var board = new firmata.Board("/dev/ttyACM0", function(){

    console.log("Connecting to Arduino");

    board.pinMode(0, board.MODES.ANALOG); // enable analog pin 0

    board.pinMode(1, board.MODES.ANALOG); // enable analog pin 1

    board.pinMode(2, board.MODES.OUTPUT); // direction of DC motor

    board.pinMode(3, board.MODES.PWM); // PWM of motor

    board.pinMode(4, board.MODES.OUTPUT); // direction of DC motor

});

function handler(req, res) {

    fs.readFile(__dirname + "/example28.html",

    function (err, data) {

        if (err) {

            res.writeHead(500, {"Content-Type": "text/plain"});

            return res.end("Error loading html page.");

        }

    res.writeHead(200);

    res.end(data);

    })

}

var desiredValue = 0; // desired value var

var actualValue = 0; // actual value var

var factor = 0.1; // proportional factor that deterimes speed of res.

var pwm = 0; // set pwm as global variable

http.listen(8080); // server will listen on port 8080

var sendValueViaSocket = function(){}; // var for sending messages

board.on("ready", function(){

board.analogRead(0, function(value){

    desiredValue = value; // continuous read of analog pin 0

});

board.analogRead(1, function(value){

    actualValue = value; // continuous read of analog pin 1

});

startControlAlgorithm();

io.sockets.on("connection", function(socket) {

    socket.emit("messageToClient", "Srv connected, board OK");

    setInterval(sendValues, 40, socket); // on 40ms trigerr func. sendValues

}); // end of sockets.on connection

}); // end of board.on ready

////////////////////////////////////////////////fuzzy

var NFuzzyVars = 2;

var NFuzzyOutputs = 1;

var NFuzzySets = new Array(NFuzzyVars);

NFuzzySets[0] = 3;

NFuzzySets[1] = 3;

var FSvalues = new Array(NFuzzyVars);

for (var i=0;i!=NFuzzyVars;i++)

{

    FSvalues[i] = new Array(NFuzzySets[i]);

    for (var j=0;j!=NFuzzySets[i];j++)

    {

        FSvalues[i][j] = new Array(3);

    }

}

var NRules = 3;

var RBase = new Array(NRules);

for (var i=0;i!=NRules;i++)

{

    RBase[i] = new Array(NFuzzyVars);

}

var ValuesForFuzzy = new Array(NFuzzyVars);

ValuesForFuzzy[0] = 0;

ValuesForFuzzy[1] = 0;

var AlphaCut = new Array(NFuzzySets[0]);

var RN = 0;

RBase[RN][0] = 0; RBase[RN][1] = 0; RN++;

RBase[RN][0] = 1; RBase[RN][1] = 1; RN++;

RBase[RN][0] = 2; RBase[RN][1] = 2; RN++;

FSvalues[0][0][0] =  -100; // number of var, num of fuzzy sets, number of points, that define fs

FSvalues[0][0][1] =  -100;

FSvalues[0][0][2] =  0;    

FSvalues[0][1][0] =  -100;

FSvalues[0][1][1] =  0;

FSvalues[0][1][2] =  100;

FSvalues[0][2][0] =  0;

FSvalues[0][2][1] =  100;

FSvalues[0][2][2] =  100;

FSvalues[1][0][0] =  -15;

FSvalues[1][0][1] =  -15;

FSvalues[1][0][2] =  0;    

FSvalues[1][1][0] =  -15;

FSvalues[1][1][1] =  0;

FSvalues[1][1][2] =  15;

FSvalues[1][2][0] =  0;

FSvalues[1][2][1] =  15;

FSvalues[1][2][2] =  15;

function getMRFromFSvalues(value,NumOfVar,NumOfSet)

{

    if (NumOfSet == 0)

    {

        if (value < FSvalues[NumOfVar][NumOfSet][0])

        {

            return 1;

        }

        else if (value > FSvalues[NumOfVar][NumOfSet][2])

        {

            return 0;

        }

        else

        {

            return (FSvalues[NumOfVar][NumOfSet][2] - value) / (FSvalues[NumOfVar][NumOfSet][2] - FSvalues[NumOfVar][NumOfSet][1]);

        }

    }

    else if (NumOfSet == NFuzzySets[NumOfVar] - 1)

    {

        if (value < FSvalues[NumOfVar][NumOfSet][0])

        {

            return 0;

        }

        else if (value > FSvalues[NumOfVar][NumOfSet][2])

        {

            return 1;

        }

        else if (value < FSvalues[NumOfVar][NumOfSet][1])

        {

            return (value - FSvalues[NumOfVar][NumOfSet][0]) / (FSvalues[NumOfVar][NumOfSet][1] - FSvalues[NumOfVar][NumOfSet][0]);

        }

    }

    else 

    {

        if (value < FSvalues[NumOfVar][NumOfSet][0])

        {

            return 0;

        }

        else if (value > FSvalues[NumOfVar][NumOfSet][2])

        {

            return 0;

        }

        else if (value < FSvalues[NumOfVar][NumOfSet][1])

        {

            return (value - FSvalues[NumOfVar][NumOfSet][0]) / (FSvalues[NumOfVar][NumOfSet][1] - FSvalues[NumOfVar][NumOfSet][0]);

        }

        else

        {

            return (FSvalues[NumOfVar][NumOfSet][2] - value) / (FSvalues[NumOfVar][NumOfSet][2] - FSvalues[NumOfVar][NumOfSet][1]);

        }

    }

}

function getDesiredValuesFuzzy()

{

    for (var j=0;j!=NFuzzySets[0];j++)

    {

        AlphaCut[j] = 0;

    }

    for (var i=0;i!=NRules;i++)

    {

        var tempMR = 0;

        var tempMinMR = 1;

        for (var CurrentVar = NFuzzyOutputs;CurrentVar!=NFuzzyVars;CurrentVar++)

        {

            tempMR = getMRFromFSvalues(ValuesForFuzzy[CurrentVar],CurrentVar,RBase[i][CurrentVar]);

            if (tempMR < tempMinMR)

                tempMinMR = tempMR;

        }

        for (var CurrentVar = 0;CurrentVar!=NFuzzyOutputs;CurrentVar++)

        {

            if (tempMinMR > AlphaCut[RBase[i][CurrentVar]])

                AlphaCut[RBase[i][CurrentVar]] = tempMinMR;

        }

    }

    for (var CurrentVar = 0;CurrentVar!=NFuzzyOutputs;CurrentVar++)

    {

        var FuzzyRange = FSvalues[CurrentVar][NFuzzySets[CurrentVar]-1][2] - FSvalues[CurrentVar][0][0];

        var NIntervals = 100;

        var CoordinateMassSumm = 0;

        var MassSumm = 0;

        for (var i=0;i!=NIntervals;i++)

        {

            var TempCoordinate = FSvalues[CurrentVar][0][0] + FuzzyRange/NIntervals*i;

            var TempMass1 = 0;

            var TempMass2 = 0;

            for (var j=0;j!=NFuzzySets[CurrentVar];j++)

            {

                TempMass2 = getMRFromFSvalues(TempCoordinate,CurrentVar,j);

                if (TempMass2 > AlphaCut[j])

                    TempMass2 = AlphaCut[j];

                if (TempMass2 > TempMass1)

                    TempMass1 = TempMass2;

            }

            MassSumm += TempMass1;

            CoordinateMassSumm += TempCoordinate * TempMass1;

        }

        if (MassSumm != 0) 

            ValuesForFuzzy[CurrentVar] = CoordinateMassSumm / MassSumm;

        if (ValuesForFuzzy[CurrentVar].isNaN)

            ValuesForFuzzy[CurrentVar] = 0;

    }

}

////////////////////////////////////////////////unfuzzy

function controlAlgorithm () {

    ValuesForFuzzy[1] = desiredValue-actualValue;

    console.log(ValuesForFuzzy[1]);

    getDesiredValuesFuzzy();

    pwm = ValuesForFuzzy[0];

    console.log(pwm);

    if (pwm > 255) {pwm =  255}; // to limit pwm values

    if (pwm < -255) {pwm = -255}; // to limit pwm values

    if (pwm > 0) {board.digitalWrite(2,1); board.digitalWrite(4,0);}; // direction if > 0

    if (pwm < 0) {board.digitalWrite(2,0); board.digitalWrite(4,1);}; // direction if < 0

    board.analogWrite(3, Math.abs(pwm));

};

function startControlAlgorithm () {

    setInterval(function(){controlAlgorithm();}, 30); // call the alg. on 30ms

    console.log("Control algorithm has been started.");

};

function sendValues (socket) {

    socket.emit("clientReadValues",

    {

    "desiredValue": desiredValue,

    "actualValue": actualValue

    });

};

<!DOCTYPE html>

<meta charset = utf8>

<html>

<head>

    <title>Example with potentiometer</title>

</head>

<body onload="load();">

<div>

<canvas id="canvas1" width ="200" height = "100" style="border: 1px dashed #00c3c3;"></canvas>    

</div>

<p></p>

<div id="divForPrint"></div>

<br>

<script type="text/javascript" src="/socket.io/socket.io.js"></script>

<script type="text/javascript">

var potValue1 = 0; // value of the first potentiometer

var potValue2 = 0; // value of the second potentiometer

var x1 = new Array(); // array for x1

var y1 = new Array(); // array for y1

var x2 = new Array(); // array for x2

var y2 = new Array(); // array for y2

var canvas1;

var ctx1;

function load() { // function that is started, when we open the page

    canvas1 = document.getElementById("canvas1");

    ctx1 = canvas1.getContext("2d");

    // initialization of first graph

    for (var i=0; i<200; i++) {

        x1[i] = i; // for x values are 0, 1, 2, ...

        y1[i] = 0; // for y values are 0

    };

    // initializaion of second graph

    for (var i=0; i<200; i++) {

        x2[i] = i; // x2 values are 0, 1, 2, ...

        y2[i] = 0; // for y2 values are 0

    };

};

var divForPrint = document.getElementById("divForPrint");

// var for printing messages

var numberOfLinesInLog = 20; // variable for the number of lines in log div

var counterOfLogs = 0; // variable for counting the logs

function log(msg) { // function to print messages to div with implemented scroll

    var node=document.createElement("tr"); // we create variable node as tr (table row)

    var textnode=document.createTextNode(counterOfLogs + " | " + msg); // create elem. with text

    node.appendChild(textnode); // add to "node", i.e. table row

    divForPrint.insertBefore(node, divForPrint.childNodes[0]); // insert into variable divForPrint -> document.getElementById("divForPrint");

    if (counterOfLogs > numberOfLinesInLog-1) { // if there are more numbers as e.g. 10

        divForPrint.removeChild(divForPrint.childNodes[numberOfLinesInLog]); // remove the oldest printout

    }

    counterOfLogs = counterOfLogs + 1; // increase the counter of logs

}

var socket = io.connect("192.168.254.149:8080"); // connect via socket

socket.on("messageToClient", function (msg){

    log(msg); // add msg to div

});

socket.on("clientReadValues", function(value) {

    potValue1 = value.desiredValue;

    potValue2 = value.actualValue;

    // Draw graph No1 *****************************************

    ctx1.lineWidth = "1";

    ctx1.strokeStyle = "#ff0000";

    ctx1.clearRect(0, 0, canvas1.width, canvas1.height); // clear the canvas

    ctx1.beginPath(); // to start drawing new line

    y1.splice(0, 1); // on the position 0 in the field y1 we erase one value

    y1[199] = potValue1; // new value is added at the end

    for (var i=0; i<200; i++) {

        ctx1.lineTo(x1[i], (100 - (y1[i] / 1023) * 100)); // 0,0 x,y coordinate is in upper left corner

    };

    ctx1.stroke(); // to draw the line

    // End of draw graph No1 ***********************************

    // Draw graph No2 *****************************************

    ctx1.strokeStyle = "#00ff00"; // green line

    ctx1.beginPath(); // to start drawing new line

    y2.splice(0, 1); // on the position 0 in the field y2 we erase one value

    y2[199] = potValue2; // new value is added at the end

    for (var i=0; i<200; i++) {

        ctx1.lineTo(x2[i], (100 - (y2[i] / 1023) * 100)); // 0,0 x,y coordinate is in upper left corner

    };

    ctx1.stroke(); // to draw the line

    // End of draw graph No2 ***********************************

    log(value.desiredValue + "|" + value.actualValue);

})

socket.on("disconnect", function(){

    log("Disconnected from the server"); // we print status of disconn. to div

});

</script>

</body>

</html>