PicoDSP

PicoDSP is a Minimoog-inspired virtual analog emulator running on the Raspberry Pi Pico 2 (RP2350). It leverages the power of the infinitedsp-core library to deliver a rich, low-latency audio experience directly from a microcontroller.

This project serves as a flagship implementation of infinitedsp-core in an embedded, no_std environment using the Embassy async framework.

Features

• Virtual Analog Engine: A Minimoog-inspired architecture with 3 antialiased Oscillators + Noise, Mixer, ZDF Ladder Filter, and Envelopes.
• Effects Chain: Built-in Delay (Stereo), Reverb (Mono), and Stereo Widener.
• USB Audio Class 1.0: Acts as a USB Microphone, streaming synthesized audio directly to your PC/Mac/Linux machine at 48kHz, 16-bit stereo. No DAC required for recording!
• USB MIDI: Full MIDI control over parameters (Cutoff, Resonance, Envelopes) and Note input.
• Dual Core Processing:
  • Core 0: Handles USB communication (Audio/MIDI/CDC) and system tasks.
  • Core 1: Dedicated DSP processing loop for maximum stability and low latency.
• Preset Management: Save and load presets to the Pico's internal Flash memory via MIDI SysEx.

Hardware Requirements

• Raspberry Pi Pico 2 (RP2350)
• Micro-USB cable

Note: No external DAC (Digital-to-Analog Converter) is strictly required as the audio is streamed via USB. However, there are plans to extend the code to support I2S DACs and DIN MIDI in the future.

Getting Started

Prerequisites

• Rust (stable)
• thumbv8m.main-none-eabihf target:

  rustup target add thumbv8m.main-none-eabihf

• picotool

Building

cargo build --release

Flashing

1. Hold the BOOTSEL button on your Pico 2 while plugging it in.
2. Run:

   cargo run --release

   (This uses picotool configured in .cargo/config.toml to load the ELF directly)

Or, if you prefer UF2:

picotool uf2 convert -t elf target/thumbv8m.main-none-eabihf/release/picodsp picodsp.uf2 --family rp2350-arm-s
# Then drag picodsp.uf2 to the RPI-RP2 drive

Usage

1. Connect the PicoDSP to your computer via USB.
2. It will appear as:
   • Audio Device: "PicoDSP (infinitedsp ...)" (Input device)
   • MIDI Device: "PicoDSP MIDI"
3. Open your DAW or standalone synth host.
4. Select "PicoDSP" as your Audio Input to hear the synth.
5. Route MIDI to "PicoDSP MIDI" to play notes.

MIDI CC Map

CC #	Parameter
1	Mod Wheel
5	Portamento Time
64	Sustain Pedal
71	Filter Resonance
74	Filter Cutoff
120	All Sound Off
123	All Notes Off

Architecture

The project is structured as follows:

• src/common: Shared constants and data structures.
• src/control: MIDI handling and parameter logic.
• src/data: Preset definitions and Flash storage management.
• src/dsp: DSP graph construction (Oscillators, Filters, Effects).
• src/tasks: The main tasks for Core 0 (System/USB) and Core 1 (Audio).
• src/usb: USB descriptors and device implementation.

License

This project is licensed under the MIT License - see the LICENSE file for details.