Digital Synth VRA8-Q for Arduino Uno

Quadraphonic Synthesizer with Stereo Chorus Effector for Arduino Uno

• The 7th in the Digital Synth VRA8 series that pushes the limits of the Arduino Uno. It is a synthesizer (or MIDI sound module) that synthesizes sounds with a single 8-bit CPU, supports for playing 4-note chords, and has a built-in stereo chorus effector. The sketch is free, so you can make it with just an Arduino Uno, resistors, capacitors, and an audio jack. The sound quality can be improved by using an AC adapter and a MIDI shield. It can also be built into game consoles or musical instruments.
• https://github.com/risgk/digital-synth-vra8-q

Made by ISGK Instruments

• We are an electronic instrument making club based in Hamamatsu City, Shizuoka Prefecture, Japan. A few years ago, we started making electronic crafts to exhibit at Maker Faire, and before we knew it, we were building electronic instruments. By making synthesizers, we rediscovered the charm of synthesizers.
• https://risgk.github.io/

Features

• Serial MIDI In (38.4 kbps) or MIDI In (31.25 kbps)
• PWM Audio Out (Pin 6, Unipolar, Line Level), PWM Rate: 62.5 kHz
• Sampling Rate: 31.25 kHz, Bit Depth: 8 bits

Demo Sound

• Digital Synth VRA8-Q v3.2 Demo (Recording from Arduino Uno + Delay FX) - YouTube https://youtu.be/qLk1qMklZn4

VRA8 Series

• Digital Synth VRA8-N https://www.instructables.com/Digital-Synth-VRA8-N-for-Arduino-Uno/

Required Hardware

• A1: Arduino Uno Rev3
• U1: Audio jack (3.5 mm stereo mini)
• R1, R2: 220 ohm resistor
• C1, C2: 100 nF capacitor
• Wires

Wiring

• See the images

1. Download the sketch and extract it.
   • From https://github.com/risgk/digital-synth-vra8-q/releases/latest
2. Download Hairless MIDI<->Serial Bridge and extract it.
   • From https://projectgus.github.io/hairless-midiserial/
3. Download loopMIDI and install it.
   • From https://www.tobias-erichsen.de/software/loopmidi.html

Explanation for Windows

1. Write DigitalSynthVRA8Q.ino to Arduino Uno and quit Arduino IDE.
   • CAUTION: We strongly recommend Arduino AVR Boards core 1.8.3.
2. Start loopMIDI.
3. Start hairless-midiserial.exe (Hairless MIDI<->Serial Bridge).
   • Select Arduino Uno (COM*) on Serial Port.
   • Select loopMIDI Port on MIDI In.
   • Set [File] > [Preferences] > [Baud rate] to 38400 bps.
4. Open vra8-q-ctrl.html (VRA8-Q CTRL) with Google Chrome.
   • Select a MIDI controller on MIDI IN (if you have it).
   • Select loopMIDI Port on MIDI OUT.
5. Click (or touch) the Software Keyboard, and you can hear the sound.