Internet of Customers – Arduino, RFID, HTTP PUT & Node.js

In our last post we featured an Arduino powered RFID reader interacting with via Node.js application running on Heroku. In this post we are going to dive into detail to understand what exactly an Arduino is, how the Arduino was physically configured and the application code required to create our proof.


What exactly is Arduino?
The following is far from an official explanation, but the following best represents what I found so appealing and useful about the platform.

[pullquote]Arduino is a hardware platform that allows people to experiment with various electronics by loading their own programs onto the device. No soldering iron is needed and due to Arduino being open source, many potential components exist for it.[/pullquote]

In short – it is a great platform to quickly hack together quick concepts with, before having to invest large amounts of time and money to achieve and has an excellent community supporting it.

Setting up the Arduino
This way my first time using an Arduino and in order to experiment with a wide range of capabilities, I grabbed a kit from Adafruit. With all of the amazing functionality that various Arduino modules provide, it is not without some issues given the technology is aimed at enthusiasts and after significant trial and error, I had to update the firmware on a Wifi Shield I added that was required for the sample below.


With our proof of concept we needed to allow the Arduino to

  1. Connect to the internet / WiFi network
  2. Read the RFID code from an RFID tag
  3. Fire an HTTP PUT with the code to our Node.js application

Physically configuring the device was pretty simple and the physical architecture is as follows.  Please note the drawing on the right showing the wiring paths excludes the Wifi Shield.  The shield simply rests directly on the Arduino Uno, so the connection paths will remain the same per the Fritzing generated diagram below.


Putting it All Together
Using the configuration above with the code sample below, you will be able to place an RFID card in front of the reader – causing the light to switch from Red to Green and the resulting output should display within your consoles.  The code for our Node.js will appear in our next post, so for now, we can focus on the the Arduino IDE console.  Click the images below to see the application in action!

Note – in order to receive console output you must have a connection from your IDE directly to the device in some fashion – I used a cable to directly attach.

Running Code on the Arduino
With the hardware configured it was finally time to get our device online and ready to send data to our services running on Heroku (these will be covered in our next post).

The following code essentially merges 2 samples from the arduino site, 1 for Wifi networking, 1 for reading RFID codes. Both examples then needed modification in order to work, as most Wifi samples do not cover HTTP PUTs and the RFID reader did not work with OOTB code.

Please note the code below if for a proof and not ready for use in production!

  Sample code to read an RFID Tag ID and make HTTP PUT
  to service running on Heroku via Node.js.  Code sample created using
  some of the following resources
  - WiFi
  - WEP
  - RFID (EM4x50 Tags)
  More at


char ssid[] = "XXXXX"; // your network SSID (name)
char key[] = "XXXXX"; // your network key

// Keep track of web connectivity
boolean lastConnected = false;
boolean incomingData = false;
int status = WL_IDLE_STATUS; // the Wifi radio's status
int keyIndex = 0; // your network key Index number

// Take care of advoiding duplicate posts
unsigned long lastConnectionTime = 0;
const unsigned long postingInterval = 10*1000;

// Removing duplicate card reads
unsigned long lastReadTime = 0;
const unsigned long pollingInterval = 10*1000;

IPAddress server(192,168,1,100);  // numeric IP (no DNS)

// Initialize the Ethernet client library
// with the IP address and port of the server
// that you want to connect to (port 80 is default for HTTP):
WiFiClient client;

#define RFID_READ 0x01
#define txPin 6
#define rxPin 8

SoftwareSerial mySerial(rxPin, txPin);
int val;
int runs = 0;

String completeRFIDCode;

void setup()
  Serial.println("Starting - RFID and WiFi POC Test");

  while (!Serial) {
    ; // wait for serial port to connect. Needed for Leonardo only

  // check for the presence of the shield:
  if (WiFi.status() == WL_NO_SHIELD) {
    Serial.println("WiFi shield not present");
    // don't continue:

  // attempt to connect to Wifi network:
  while ( status != WL_CONNECTED) {
    Serial.print("Attempting to connect to WEP network, SSID: ");
    status = WiFi.begin(ssid, keyIndex, key);

    // wait 10 seconds for connection:

  Serial.println("Connected to WiFi...");


  pinMode(txPin, OUTPUT);
  pinMode(rxPin, INPUT);

void suppressAll() // Suppresses the "null result" from being printed if no RFID tag is present
  if(mySerial.available() > 0)

void loop()
  int val;
  completeRFIDCode = "";
  String segmentOne;
  String segmentTwo;
  String segmentThree;
  String segmentFour;


  if(mySerial.available() > 0)
    // The procedure is called, but the result is not printed because I don't want
    // the "error message: 1" cluttering up the serial monitor
    val =;
    // If the error code is anything other than 1, then the RFID tag was not read correctly and any data
    // collected is meaningless. In this case since we don't care about the resultant values they can be suppressed
    if (val != 1)

  // Clear segmentOne
  segmentOne = "";

  // Had some issues around detection of different RFID types
  if(mySerial.available() > 0) {
    val =;
    segmentOne = String(val, HEX);

  if(mySerial.available() > 0) {
    val =;
    segmentTwo = String(val, HEX);

  if(mySerial.available() > 0) {
    val =;
    segmentThree = String(val, HEX);

  if(mySerial.available() > 0) {
    val =;
    segmentFour = String(val, HEX);

  // If something was read in the first segment and it has been awhile since the last read, set an aggregated code for
  // the RFID code value - I am certain there is a more effective way, but this works for the proof
  if (segmentOne.length() > 0 && (millis() - lastReadTime > pollingInterval)) {
    completeRFIDCode = segmentOne + "" + segmentTwo + "" + segmentThree + "" + segmentFour;
    Serial.println("Card Detected: " + completeRFIDCode);
    Serial.println("<-----------------");     Serial.println();     lastReadTime = millis();   }   else {     Serial.println("Polling...");   }     // Send data if we picked up anything via RFID   if (completeRFIDCode.length() > 3)
    // Ensure that we have not recently sent data to our service to stop duplicate posts
    if(!client.connected() && (millis() - lastConnectionTime > postingInterval)) {


void sendData() {
  Serial.println("Trying to send card data to server...");

  // if you get a connection, report back via serial:
  // change port info as needed, this was used with a local instance via Heroku command line
  if (client.connect(server, 3001)) {
    Serial.println("Connected to server...");

    String feedData = "n{"carddata" : {"cardid" : "" + completeRFIDCode + ""}}";
    Serial.println("Sending: " + feedData);

    client.println("PUT /card/ HTTP/1.0");

    client.println("Content-Type: application/json");
    client.println("Content-Length: " + String(feedData.length()));
    client.print("Connection: close");

    Serial.println("Data has been sent...");

    lastConnectionTime = millis();
    lastConnected = client.connected();

    // Show any response from the service - helpful for debugging
    while (client.available() && status == WL_CONNECTED) {
      if (incomingData == false)
        Serial.println("Receiving data from server...");
        incomingData = true;
      char c =;

    // Clean up the connection

    if (incomingData == true) {
      incomingData = false;

    // Reset RFID code
    completeRFIDCode = "";

    lastConnected = client.connected();
  else {
    Serial.println("*** ERROR: Failed connection ***");

void printWifiStatus() {
  // Print the SSID of the network you're attached to:
  Serial.println("WiFi Status...");
  Serial.print("SSID: ");

  // Print your WiFi shield's IP address:
  IPAddress ip = WiFi.localIP();
  Serial.print("IP Address: ");

  // Print the received signal strength:
  long rssi = WiFi.RSSI();
  Serial.print("Signal Strength (RSSI):");
  Serial.println(" dBm");

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