Arduino, Ethernet Shield, Node.js and AWS OpsWorks

After going though a lot of the great examples I wanted to dive into connecting the Arduino to the internet and figure out a way to push sensor data to the web for later consumption. Thanks to Remote logging with Arduino and Node.js at FRENKI.NET I was able to get the info I needed to setup a simple data collector application.

[code language=”cpp”]
//Sending one Analog Value to a Node.js server
//Used AWS OpsWorks and created basic Stack to deploy a node.js instance
//Stolen from FRENKI.NET


byte arduinoMac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
// desired IP for Arduino
IPAddress arduinoIP(192, 168, 1, 100);
// port of Arduino
unsigned int arduinoPort = 8080;

// IP of node.js server setup to recieve the data
IPAddress receiverIP(00, 00, 00, 00);
// Port on node.js server that is listening to UDP traffic
unsigned int receiverPort = 7777;

EthernetUDP Udp;

int sensorPin = A4; // Choose whatever sensor pin you would like to use
int sensorValue;

void setup() {
Ethernet.begin(arduinoMac,arduinoIP); //Initialize Ethernet UDP and Serial port

void loop() {
sensorValue = analogRead(sensorPin); // Read sensor value and store in sensorValue
byte valueInBytes[2] = {lowByte(sensorValue), highByte(sensorValue)}; //convert it to a byte array for the UDP Transfer
// Debug info for figuring out how byte array works
Serial.print("Low: ");
Serial.print("High: ");

// Send UDP Packet to node.js server
Udp.beginPacket(receiverIP, receiverPort); //start udp packet
Udp.write(valueInBytes, 2); //write sensor data to udp packet
Udp.endPacket(); // end packet
// Repeat every 5 seconds

node code:

Here is a snippet of node.js code used to receive the Arduino data. I used a simple AWS OpsWorks Deployment of an node.js instance. Add the following code to a file…arduindocollect.js and then run #node arduinocollect.js…


var dgram = require("dgram");
var server = dgram.createSocket("udp4");
var fs = require(‘fs’);

var crlf = new Buffer(2);
crlf[0] = 0xD; //CR – Carriage return character
crlf[1] = 0xA; //LF – Line feed character

server.on("message", function (msg, rinfo) { //every time new data arrives do this:
console.log("server got: " + msg.readUInt16LE(0) + " from " + rinfo.address + ":" + rinfo.port); // you can comment this line out
fs.appendFile(‘mydata.txt’, msg.readUInt16LE(0) + crlf, encoding=’utf8′);//write the value to file and add CRLF for line break

server.on("listening", function () {
var address = server.address();
console.log("server listening " + address.address + ":" + address.port);

server.bind(7777); //listen to udp traffic on port 7777


AWS – Make sure you update the Security Group to allow UDP on 7777 or whatever UDP Port you decide to use.

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