The Official Raspberry Pi Projects Book - Projects_Book_v4

Tutorial

raspberrypi.org/magpi The Official Raspberry Pi Projects Book 103

3V3

GP2

GP3

GP4

GND

GP17

GP27

GP22

3V3

GP10

GP09

GP11

GND

DNC

GP5

GP6

GP13

GP19

GP26

GND

5V

5V

GND

GP14

GP15

GP18

GND

GP23

GP24

GND

GP25

GP8

GP7

DNC

GND

GP12

GND

GP16

GP20

GP21

3V3

GP2

GP3

GP4

GND

GP17

GP27

GP22

3V3

GP10

GP09

GP11

GND

DNC

GP5

GP6

GP13

GP19

GP26

GND

5V

5V

GND

GP14

GP15

GP18

GND

GP23

GP24

GND

GP25

GP8

GP7

DNC

GND

GP12

GND

GP16

GP20

GP21

MAKE A WHOOPI CUSHION

Making the Whoopi cushion
Cut a circle from the cardboard to fit the centre of the
‘eating’ side of each paper plate. Tape or stick squares
of foil onto the cardboard. These are your contacts:
when they touch, they will complete a circuit. Using
some copper tape, connect the foil to the edge of the
plate. Chop the sponge up into cuboid chunks and
glue them around the foil on one of the plates: this
will stop the foil squares touching each other until
someone sits on the plate. It should look something
like Figure 1.
Put the two plates together so that the foil pieces
are on the inside and facing each other. Offset the
paper plates so that the copper tape sections are
not touching.
You now have a ‘cushion’ made of two plates. You
can tape the plates together, or you might choose to
use bulldog or paper clips so that you can test that
your cushion works correctly, and easily debug any
hardware problems.

Connect the Whoopi cushion to the Pi
Plug one header lead (it doesn’t matter which) onto
a ground (GND) pin on the Pi (refer to Figure 2). Plug
the other wire onto the GPIO 2 pin (Figure 3, overleaf)
and then clip a crocodile clip cable to one of the paper
plates’ copper tape sections. Connect the other end of
the crocodile clip cable to the male pin of one of the
connected jumper wires (Figure 4). Repeat these last
two steps to connect the other plate to your Raspberry
Pi. Your setup should look similar to Figure 5.

Test the sound

That’s the hardware complete. Now for the software!

We’re going to use Python. Don’t worry if you haven’t

used it before: just follow the instructions and you’ll

pick it up. You’ll be using the command line to enter

commands. To do this you’ll need to open a terminal

window by clicking on the terminal icon: it looks like a

computer screen, and is found three icons along from

the Menu button on your desktop.

Figure 1 It looks a bit

like some futuristic

tech. We’ll use it to

make farting sounds

Figure 2 If you have

an older Raspberry

Pi model you'll

only have 26 pins,

but they have the

same layout