main.js

/*jslint node:true,vars:true, unparam:true */
/*jshint unused:true */


/*
The Touch Notifier Node.js sample application distributed within Intel® XDK IoT Edition under the IoT with Node.js Projects project creation option showcases how to read digital data from a Grover Starter Kit Plus – IoT Intel® Edition Touch 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-touch-notifier-nodejs-and-html5-samples
*/

//MRAA Library was installed on the board directly through ssh session
var mraa = require("mraa");

//GROVE Kit Shield D6 --> GPIO6
//GROVE Kit Shield D2 --> GPIO2
function startSensorWatch(socket) {
    'use strict';
    var touch_sensor_value = 0, last_t_sensor_value;

    //Touch Sensor connected to D2 connector
    var digital_pin_D2 = new mraa.Gpio(2);
    digital_pin_D2.dir(mraa.DIR_IN);

    //Buzzer connected to D6 connector
    var digital_pin_D6 = new mraa.Gpio(6);
    digital_pin_D6.dir(mraa.DIR_OUT);

    digital_pin_D6.write(0);

    setInterval(function () {
        touch_sensor_value = digital_pin_D2.read();
        if (touch_sensor_value === 1 && last_t_sensor_value === 0) {
            console.log("Buzz ON!!!");
            socket.emit('message', "present");
            digital_pin_D6.write(touch_sensor_value);
        } else if (touch_sensor_value === 0 && last_t_sensor_value === 1) {
            console.log("Buzz OFF!!!");
            //socket.emit('message', "absent");
            digital_pin_D6.write(touch_sensor_value);
        }
        last_t_sensor_value = touch_sensor_value;
    }, 500);
}

//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>');
    console.log("Created a server???");
}).listen(1337);
var io = require('socket.io')(app);

console.log("Sample Reading Touch Sensor");

//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');
    });
});