Dobot - first try

gistfile1.js

/**
* Created by olipion on 2/8/16.
* My first shot at reverse engineering java application. 
*/
    
var SerialPort = require("serialport").SerialPort;
var serialPort;
    
    
/**
 * Use a Uint8Array as an input and create a float array containing nb float starting at offset.
 * This use a reverse byte array. most likely because arduino and this computer does not share the same endianess.
 * @param inArray {Uint8Array} array of byte to parse
 * @param nb {Integer} number of entries
 * @param offset {Integer} number of byte to skip
 * @returns {Array} output : array of float
 */
var getFloatArrayFromUInt8ArrayReverse = function(inArray, nb, offset) {
    var fArray = [];
    var offset = (offset === undefined) ? 0 : offset;
    var tmpArray = new Uint8Array(4);
    var dataView = new DataView(tmpArray.buffer);

    for (var i = 0;i < nb;i++) {
        var offsetInArray = i * 4 + offset;
        tmpArray[0] = inArray[offsetInArray + 3];
        tmpArray[1] = inArray[offsetInArray + 2];
        tmpArray[2] = inArray[offsetInArray + 1];
        tmpArray[3] = inArray[offsetInArray + 0];
        fArray.push(dataView.getFloat32(0));
    }
    return fArray;
}



/**
 * Use a byte array and translate it into a string
 * @param hex
 * @returns {Array}
 */
function bytesToHex(bytes) {
    for (var hex = [], i = 0; i < bytes.length; i++) {
        hex.push((bytes[i] >>> 4).toString(16));
        hex.push((bytes[i] & 0xF).toString(16));
    }
    return hex.join("");
}



/**
 * Send begin package to a specific port
 * @param port {SerialPort} port to use
 */
function sendBeginPackage(port) {

    var beginPackage = [0xa5,0x00, 0x00,0x11,0x11,0x22,  0x22,0x33,0x33,0x00,  0x00,0x00,0x00,0x00,  0x00,0x00,0x00,0x00,
                        0x00,0x00,0x00,0x00,  0x00,0x00,0x00,0x00,  0x00,0x00,0x00,0x00,  0x00,0x00,0x00,0x00,
                        0x00,0x00,0x00,0x00,  0x00,0x00,0x00,0x5a];
    port.write(beginPackage,function() {
        console.log("initial data written");

    })
}

var connectToDobot = function(comName) {
    console.log("Create serial link ....");
    serialPort = new SerialPort(comName, {
        baudRate: 256000
    });
    serialPort.on("open", function () {
        console.log('serial port is opened');
        sendBeginPackage(serialPort);
    });

    serialPort.on('data', function(data) {
        console.log('Received ' + data.length);

        if (data.length == 38) {
            console.log(bytesToHex(data));
            var floatArray = getFloatArrayFromUInt8ArrayReverse(data,9,1);
            console.log(Array.apply([], floatArray).join("  "));
        }
        //console.log(bytesToHex(data));
    });

    serialPort.on('error', function() {
        console.log('serial cannot be opened.');
    });
}

var serialPort = require("serialport");
serialPort.list(function (err, ports) {
    ports.forEach(function(port) {
        if (port.comName === "/dev/cu.BT4-SPP-SerialPort")
        {
            console.log("Found BT4 board. try to connect to it.");
            connectToDobot(port.comName);
        }
    });
});





var timer = setInterval(function(){
    console.log("wait ...");
},1000);