guinea-synth

an synthesizer made out of surplus Raspberry Pi

See demo video.

hardware list

• Raspberry Pi
• 16x2 LCD I2C display
• rotary encoder with switch
• USB MIDI controller
• some wires and LEGO to keep it together

you need to setup that display first - see https://github.com/the-raspberry-pi-guy/lcd

wiring diagram

Display	Raspberry Pi
GND	pin 6 (GND)
VCC	pin 4 (5V)
SDA	pin 3 (GPIO 2)
SCL	pin 5 (GPIO 3)

see https://pinout.xyz/#

Rotary encoder	Raspberry Pi
CLK	pin 19 (GPIO 9)
DT	pin 21 (GPIO 10)
SW	pin 22 (GPIO 25)
+	pin 17 (5V)
GND	pin 20

DT and CLK pins can be exchanged, it just switches knob direction.

software setup

install these things from apt:

• python2.7
• CSound
• python-csound

add this to your crontab -e:

@reboot /home/patch/guinea-synth/autostart.sh &

You have three synthesizers in one box:

• amateur.csd - sample-based morphing synth
• analog_nomad.csd - flexible polsynth (Juno-like)
• traveller.csd - monosynth for weird sounds

API

TODO - now only method signatures are documented.

• cls()
• echo(text, linenum=0)
• menu(obj)
• act_menu(), menu.add(item)
• act_select(label, params, callback)
• act_confirm(prev, question, callback)
• csd_param(prev, csd, param_name, label, preset=1, min=0, max=1, per_round=20.0)
• csd_select(prev, csd, param_name, label, preset=0, params=[])
• csd_checkbox(prev, csd, param_name, label, preset=0)

known bugs

• sometimes some notes are stuck when playing chords, you need to reset synth

ideas & todo

• sequencer
• loading & saving presets
• refactor python code

credits & thanks

• based on many opensource tools
• ctCsound by (C) 2016 Francois Pinot
• LCD driver by Ryanteck LTD
• uses Adventure Kid Single Cycle Waveforms
• used code from https://blog.amnuts.com/2017/01/11/rotary-volume-control-for-the-raspberry-pi/
• many thanks to Rory Walsh for introducing me to CSound