raspberrypi.org/magpi The Official Raspberry Pi Projects Book 81
FM TOUCH SYNTH Projects
>STEP-01
Making a case
The wooden case was Toby’s first project using
his new CNC machine. It houses the components,
including the matrix of RGB LEDs that sit under the
touchscreen overlay.>STEP-02
Teensy bit of help
Eight rotary knobs and the touchscreen overlay are
wired up to a Teensy 3.6, which sends control data
to the Pi Zero and also handles audio output.>STEP-03
Pure Data programming
All the synthesiser sounds are processed on the Pi
Zero using Pure Data, a visual programming language
in which objects can be created and linked together.BUILD A
TOUCHSCREEN
SYNTH
Above Toby is pleased with the case,
crafted using his new CNC machine:
“I think all my future projects will have
wooden cases”Rather than displaying
information on a regular
touchscreen, Toby opted to use LEDs
for everything, including menus.
“It’s a bit more archaic and cryptic.
I like to make instruments that you
really have to learn to use, and aren’t
immediately super-accessible. Sort
of like the old hand-held video
games I grew up with.”
One drawback is that the
resistive overlay can only handle
one touch at a time, although a
workaround involves sustaining
notes. “I added the sustain feature
close to the end of the project
because I wanted polyphony. The
synth just sounds so massive when
you play it polyphonically. Perhaps
in the future I’ll upgrade the screen
to allow multitouch.”
Live project
Toby has already used the FM
Touch Synth in live performances.
“It’s working out great! I’ve
been doing a lot of ambient jam
sessions with it, turning the delay
way up and feeding into my Pi
Looper. It’s been a lot of fun.”
Toby would really like to make
the synth available commercially,
which is why he hasn’t released
the code yet, but he’s already
working on another Pi Zero
project: “a looper in which
you can manipulate the pitch
and speed of the loop in four
different slots.”The menus are a
bit hard to fathom
at first sight, but
they include
presets, sound
parameters,
vertical position
effects, and a
voice level mixer