Adafruit has taken their popular PN532 breakout board and turned it into a shield – the perfect tool for any 13.56MHz RFID or NFC application. The Adafruit NFC shield uses the PN532 chip-set (the most popular NFC chip on the market) and is what is embedded in pretty much every phone or device that does NFC. This chipset is very powerful, and can pretty much do it all, such as read and write to tags and cards, communicate with phones (say for payment processing), and even emulate NFC tags. While the controller has many capabilities, the Arduino library currently only supports reading & writing tags, and does not support phone-to-shield communication, tag emulation (which requires an external ‘secure element’ only available from NXP), or other more advanced features at this time.
The Adafruit shield was designed by RF engineers using the best test equipment to create a layout and antenna with 10cm (4 inch) range, the maximum range possible using the 13.56MHz technology. You can easily attach the shield behind a plastic plate with standoffs and still read cards through a (non-metal) barrier.
This shield is designed to use I2C or SPI communication protocols. I2C is the default, as it uses fewer pins: analog 4 and 5 are used for I2C (of course you can still connect other I2C devices to the bus). Digital #2 is used for “interrupt” notification. This means you don’t have to sit there and ‘poll’ the chip to ask if a target tag has been found, the pin will pull low when a card, phone, etc is within range. You can adjust which pin is used if you need to keep digital #2 for something else. It is also easy to change the shield over to SPI where you can use any 4 digital pins by shorting two solder jumpers on the top of the PCB. Compatible with any “classic” Arduino – NG, Diecimilla, Duemilanove, UNO – as well as Mega R3 or later. For using the I2C interface with Mega R2 or earlier, two wires must be soldered as the I2C pins are in a different location on earlier Megas.
Comes with: The Adafruit PN532 shield including a tuned 13.56MHz stripline antenna, 36-pin 0.1″ header for attaching the shield to an Arduino, and we also toss in a 13.56MHz RFID/NFC 1K card!