9

FORGE

NFC is a great medium for small amounts of data,
such as a simple message, a weblink, or a task trigger.
This was used in great effect in Matt Brailsford’s tape
deck, where he put an NFC tag in old cassettes to
trigger a task (hsmag.cc/JSpoXa). In this case, it was
triggering Spotify playlists. The code for such a thing
is pretty straightforward: you need the NFC reader to
scan for a tag, either constantly or on a button press,
and then do something with the data it reads.
This principle works for most tasks – you just have
to choose what item you put your NFC tag into, and
what to do with the data once you’ve read it! There is

a lovely tutorial by Tony Di Cola on the Adafruit website
about making paper Minecraft blocks and using them
to build blocks in the game. There was a recent
art exhibition in Sheffield where the artist, Caroline
Claisse, used NFC data tags in items for the audience
to interact with her exhibition, triggering animations
and lighting by bringing an object up to the artwork.
The exact code will depend on the hardware you’re
using. If you buy from a maker store, they should give
you details of how to use the appropriate libraries
for your parts. Roughly, your program should follow
this pseudo-code:

Look for a NFC card or sticker.

Read the data from the sticker.

Select the block of data that is useful to you.

Do something with it.

Write new data onto a block, or all of

the blocks.

With just those few examples, you’ll realise that

NFC can bring a level of interactivity to your projects

for a large number of people, and at a relatively

low cost. If you have a light display, you could have

a number of physical objects of different colours,

and as you bring them towards a reader, the colour

changes to that of the object. The tags are generally

rewritable and you can change what they store

pretty easily.

SHARE INFORMATION EASILY

Another use for the NFC tags isn’t just in the project

• why not use them to store a link to your build
  site for the project, so when you inevitably run out
  of cards at an event, people can bring up your site
  immediately on their phone? If you do this, be a little
  bit careful which NFC tags you buy, as not all are
  supported by modern phones. There’s a compatibility
  chart at hsmag.cc/OCcXOd.

WHAT TO STORE?

Most Mifare Classic NFC tags (the most common

kind) will store 1kB of data. As with data cards

YOU’LL NEED

PN532 breakout

with a Raspberry

Pi 3

Pimoroni NFC

data tags and the

coloured LED nail

stickers

NFC stickers

from ZipNFC (UK

based): zipnfc.com

Midas ‘Tiny’

NTAG213 for my

initial experiments

on thumbnails

NFC reader/writer

Check your phone’s

compatibility at

hsmag.cc/HbfDRT

For the coil

Single LED

Approx 40 cm

of wire

Two bits of

heat‑shrink

Solder

Soldering iron

Left

We use many parts of

the electromagnetic

(EM) spectrum

to transfer data

and energy in our

everyday activities.

NFC is part of the

radio waves section

DIY NFC COIL

To make your own, take a piece of wire and then

thread two pieces of heat-shrink tubing onto it. Coil

the wire up so it makes several loops, keeping the LED

connected. Solder each leg of a 5 mm LED to each end

of the wire. Pull the heat-shrink tubing up to cover the

solder joints, and shrink it. Hold the coils in an NFC

field and the LED should flash. See Figure 1 overleaf.

Radio

waves

LONG WAVELENGTH

NFC

SHORT WAVELENGTH

Micro-

waves

Visible

light

UV X-ray Gamma

ray

IR

NFC is a great medium for

small amounts of data,

such as a simple message,

a weblink, or a task trigger

”

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