Using an Uno configured with an Adafruit RFID-NFC shield to send the UID values to a desktop game I am building.

Works fine. However, in addition to just the UID, I need to send 1 additional value, lets call it 'game choice'. This can be one of 3 values. This is just the relevant code. Can any experts suggest how I might modify the following to send this additional value?

#include <Wire.h>
#include <Adafruit_NFCShield_I2C.h>

#define IRQ   (2)
#define RESET (3)  // Not connected by default on the NFC Shield

Adafruit_NFCShield_I2C nfc(IRQ, RESET);

void setup(void) {


  uint32_t versiondata = nfc.getFirmwareVersion();
  if (! versiondata) {
    Serial.print("Didn't find PN53x board");
    while (1); // halt
  // Got ok data, print it out!
  Serial.print("Found chip PN5"); Serial.println((versiondata>>24) & 0xFF, HEX); 
  Serial.print("Firmware ver. "); Serial.print((versiondata>>16) & 0xFF, DEC); 
  Serial.print('.'); Serial.println((versiondata>>8) & 0xFF, DEC);

  // configure board to read RFID tags

void loop(void) {
  uint8_t success;
  uint8_t uid[] = { 0, 0, 0, 0, 0, 0, 0 };  // Buffer to store the returned UID
  uint8_t uidLength;                        // Length of the UID (4 or 7 bytes depending on ISO14443A card type)
  int nfcDEC;  
  success = nfc.readPassiveTargetID(PN532_MIFARE_ISO14443A, uid, &uidLength);

  if (success) {

   nfc.PrintHex(uid, uidLength );
  • Could you elaborate on what you want to send, from where and to whom? Its not entirely clear.
    – asheeshr
    Commented Apr 3, 2014 at 14:01
  • The message is sent obviously whenever a user scans their tag over 1 of 3 possible scan targets(game choices). This 'game choice' value would be hardcoded. The receiving end is a desktop Adobe AIR application. Using the ArduinoConnector native Extension code.google.com/p/as3-arduino-connector
    – Bachalo
    Commented Apr 3, 2014 at 14:32
  • so 3 arduinos+3 shields, 1 used for each choice and COM port
    – Bachalo
    Commented Apr 3, 2014 at 14:41

1 Answer 1


had to simply modify PrintHex in Adafruit_NFCShield_I2C.h

to accept an additional argument

  • 4
    Could you explain a bit more on what you changed (show relevant code)? The answer in its current form isn't very useful to others having the same issue.
    – sachleen
    Commented Apr 4, 2014 at 20:08

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