■ FIGURE 2. The Wave Shield lets you play
standard WAV files using an Arduino Uno (or
compatible) as a controller. It has an onboard
amplifier, but you'll get a more impressive result if
you connect it to an external amplified speaker.
ghost, monster, mummy, zombie, whatever.
I’ve arranged for a small assortment of
professionally decorated t-shirts that fit the bill
(available online) in various sizes from adult
small to 4XL. Check the Sources box for
additional info. All are silkscreen printed, and
will withstand many washes. The bandages in
the Mummy design shown in Figure 1 use a
glow-in-the-dark paint that adds to the thrill
The only required alteration to the shirt is
poking a small hole in the center of each eye.
The holes allow the LEDs to pop through from
the back. Once cut, the shirt fabric may fray
over time around the hole. You can reduce or
eliminate that by applying a small dab of Dritz Fray Check
(available at any yardage or notions store) to the perimeter
of the hole.
Building the Electronics
At the heart of the electronics for this shirt is an
Arduino Uno (or compatible) microcontroller. Your
Arduino needs to use the Atmel ATmega328 chip and not
the less capable ATmega168 (this was the chip used in
older models of the Arduino).
Attached to the top of the Arduino is a Wave Shield
board from Adafruit Industries (see Figure 2). This low
cost ($22) kit adds the ability to play standard WAV sound
files through your Arduino. As its name implies, the Wave
Shield is a shield board that plugs directly over the
Arduino. All electrical connections between the two
are made automatically. The Wave Shield comes in
kit form, but is easy to assembly. Adafruit provides
excellent step-by-step build instructions.
Once the Wave Shield is constructed, double-check your wiring, and then sandwich the shield to
your Arduino. Make sure all the pins from the shield
are inserted into their correct corresponding
connections on the Arduino.
The Wave Shield is equipped with a standard
size SD card slot, digital-to-analog converter chip,
audio amplifier, and 1/8” jack for attaching to an
outboard speaker or amplifier. (I recommend a
compact capsule-style amplified speaker, as
detailed later.) To use the shield, you merely copy
one or more WAV sound files from your computer
to a compatible SD card, then slip the card into the
slot on the Wave Shield. More on this later.
Several connection points on the Wave Shield
are configurable. To complete the wiring of the shield, you
must add jumpers as indicated in the online
documentation. Unless you have a specific reason
otherwise, connect the jumpers to their respective
Arduino pins as shown in these docs. That way, you won’t
have to modify the sketch code. You can use ordinary
22 gauge solid or standard conductor insulated wire for
the jumpers. Cut to length to avoid excess.
■ FIGURE 3.
from a small
piece of PCB.
It serves as
September 2012 33