Initial commit of a toy analogue audio generator

Key components: - no_std core so it can be used bare metal on embedded systems - default implementation for RPi 2350, with midi input and I2s output using PIO - Visualiser for the web to play with on a dev system
2026-03-23 15:06:31 +00:00
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+# Sound — Analogue Synthesiser
+
+A modular analogue synthesiser written in Rust.
+
+- **`synth-core`** — `no_std` DSP library (oscillators, filters, envelopes, LFO, MIDI). Runs on microcontrollers and WASM.
+- **`synth-visualiser`** — browser-based visualiser (oscilloscope, spectrum analyser, patch bay) compiled to WebAssembly.
+
+## Prerequisites
+
+```sh
+# Rust toolchain (stable)
+curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
+
+# WASM target
+rustup target add wasm32-unknown-unknown
+
+# wasm-pack (builds and packages the WASM module)
+cargo install wasm-pack
+```
+
+## Build
+
+### synth-core (native — tests and development)
+
+```sh
+cargo build -p synth-core
+cargo test  -p synth-core
+```
+
+### synth-core (WASM — verify it cross-compiles)
+
+```sh
+cargo build -p synth-core --target wasm32-unknown-unknown
+```
+
+### synth-visualiser (browser)
+
+Run from the workspace root:
+
+```sh
+wasm-pack build crates/synth-visualiser --target web --out-dir ../../www/pkg
+```
+
+This generates `www/pkg/` containing the compiled `.wasm` binary and the JS glue module.
+
+## Run
+
+Serve the `www/` directory with any static HTTP server. A browser is required (the Web Audio API is not available over `file://`).
+
+```sh
+# Python (no install needed)
+python3 -m http.server --directory www 8080
+
+# Or with npx serve
+npx serve www
+```
+
+Then open [http://localhost:8080](http://localhost:8080).
+
+## Microcontroller deployment
+
+`synth-core` targets bare-metal Cortex-M out of the box. Add the relevant target and uncomment the linker flags in [`.cargo/config.toml`](.cargo/config.toml).
+
+```sh
+# Example: Daisy Seed / STM32H750 (Cortex-M7)
+rustup target add thumbv7em-none-eabihf
+cargo build -p synth-core --target thumbv7em-none-eabihf
+```
+
+A microcontroller runner crate (I²S output, UART MIDI) can be added as a new workspace member when needed.
+
+## Project structure
+
+```
+sound/
+├── crates/
+│   ├── synth-core/          # no_std DSP library
+│   │   └── src/
+│   │       ├── oscillator.rs    VCO — Sine, Saw, Square, Triangle, Pulse
+│   │       ├── filter.rs        SVF — LP / HP / BP / Notch
+│   │       ├── envelope.rs      ADSR envelope generator
+│   │       ├── vca.rs           Voltage-controlled amplifier
+│   │       ├── lfo.rs           Low-frequency oscillator
+│   │       ├── midi.rs          Byte-stream MIDI parser
+│   │       ├── patch.rs         Cable routing graph
+│   │       ├── math.rs          DSP utilities (lerp, dB, MIDI→Hz)
+│   │       └── config.rs        SampleRate type
+│   └── synth-visualiser/    # WASM browser front-end
+│       └── src/
+│           ├── engine.rs        AudioContext + AnalyserNode
+│           ├── oscilloscope.rs  Time-domain canvas view
+│           ├── spectrum.rs      FFT canvas view
+│           ├── patchbay.rs      Drag-and-drop patch cables
+│           └── params.rs        SynthParams (JSON serialisable)
+└── www/
+    ├── index.html           Browser UI
+    ├── bootstrap.js         WASM loader (ES module)
+    └── pkg/                 Generated by wasm-pack (git-ignored)
+```