PlantsSystem-PRA32-U

video upload by plantssystem

"Build your own digital synth with PRA32-U × Raspberry Pi Pico!

ISGK Instruments' PRA32-U is a digital synthesizer that uses Raspberry Pi Pico.
The Pico and various circuits can be arranged smartly, making prototyping and modification a lot of fun, and allowing you to quickly put your ideas into shape.
This time I put together everything from MIDI input to sound generation and output, and it was extremely easy to use as the foundation for a homemade synth, and it was a very fun experience to build it."

https://risgk.github.io

Overview

4 Voice Polyphonic/Paraphonic Synthesizer for Raspberry Pi Pico 2/RP2350

Built-in Chorus and Delay FX

Controlled by MIDI -- PRA32-U2 is a MIDI sound module

Having the function of writing the parameters to the user programs and the flash

Modifiable with Arduino IDE and Arduino-Pico (by Earle F. Philhower, III)

An I2S DAC hardware (e.g. Pimoroni Pico Audio Pack) is required

PWM Audio can also be used instead of I2S (PWM Audio does not require an I2S DAC hardware)

Prebuilt UF2 files ("bin")

"Digital-Synth-PRA32-U2-Pimoroni-Pico-Audio-Pack.uf2" is for Raspberry Pi Pico and Pimoroni Pico Audio Pack

"Digital-Synth-PRA32-U2-PWM-Audio.uf2" is for Raspberry Pi Pico and PWM Audio

Bottom pic with control panel.


Demos by the maker Ryo Ishigaki:

MIDI Controller PRMC-1 (type-0) Demo (2025/04/13)

video upload by Ryo Ishigaki

Digital Synth PRA32-U with Panel Prototype 2 Audio Demo (2024/09/11 v2.5.1)

video upload by Ryo Ishigaki

Picophonica — A Raspberry Pi Pico synth for a toy keyboard, with instrument presets and Midi out

video upload by Turi Scandurra

"A friend gifted me a cheap toy musical keyboard. The sound quality was atrocious, and it could only play one note at a time. So I removed its circuitry while keeping its enclosure, speaker, and keybed, and with some tinkering and a Raspberry Pi Pico I turned it into something usable.

I integrated a software synthesizer into the Pico. It's pico_synth_ex by Ryo Ishigaki - ISGK Instruments. The new engine boasts two oscillators, featuring descending sawtooth and square waveforms, a customizable filter with resonance control, cutoff modulation, a Decay-Sustain amp envelope, and an LFO for added modulation possibilities.

This video shows the makeover. The soundtrack is entirely played on the Picophonica, recorded one instrument at a time through the new audio out port.

Source code: https://github.com/TuriSc/Picophonica
Blog post: https://turiscandurra.com/picophonica/"