Industrial Internet Application Development

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Preparing an SD card

To prepare an SD card, follow the sequence of actions as described:

Download the latest Raspbian LITE image (available at https://www.raspberrypi.org/downloads/raspbian/).
Connect your SD card to a computer and use Etcher (https://etcher.io/) to flash the Raspbian .img file to the SD card.
Enable SSH using the following command:

cd /Volumes/boot
touch ssh

To enable Wi-Fi, create wpa_supplicant.conf with the following content:

network={
 ssid="YOUR_SSID"
 psk="YOUR_WIFI_PASSWORD"
}

To create a file in a Linux console, you can use the GNU nano editor. It is pre-installed in most Linux distributives. All you need is to run the nano FILE_NAME command and follow the displayed instructions.

Create the /home/pi/sensor folder.
Create the /home/pi/sensor/package.json file with the following content:

{
 "name": "sensor",
 "version": "1.0.0",
 "description": "",
 "main": "index.js",
 "scripts": {
   "start": "node index.js",
   "test": "echo \"Error: no test specified\" && exit 1"
 },
 "author": "",
 "license": "ISC",
 "dependencies": {
   "rpio": "^0.9.16",
   "ws": "^2.3.1"
 }
}

Create the /home/pi/sensor/index.js file with the following content, replacing REMOTE-SERVER-ADDRESS.com with a real value:

var WebSocket = require('ws');
var rpio = require('rpio');

var ws;
var receiver = 'ws://REMOTE-SERVER-ADDRESS.com:8080';
rpio.open(11, rpio.INPUT);

var establishConnection = function () {
  ws = new WebSocket(receiver);
  ws.on('close', establishConnection);
  ws.on('error', establishConnection);
};
establishConnection();

var sendStatus = function () {
  var status = rpio.read(11) === 0;
  console.log('light status: ' + status);

  var data = JSON.stringify({
    device: 'raspberry',
    timestamp: Date.now(),
    light: status
  });

  try { ws.send(data); }
  catch (e) { console.log('failed to send data to ' + receiver); }

  setTimeout(sendStatus, 1000);
};
sendStatus();

Create the /home/pi/sensor/Dockerfile file with the following content:

FROM hypriot/rpi-node:boron-onbuild