Gately

Browser-based digital logic simulation with an experimental Arduino I/O bridge.

Live Demo · Documentation

Overview

Gately is an experimental web-based logic simulator for learning and testing digital circuits before building them on a physical breadboard. It lets you build circuits visually in the browser, run them through a custom logic engine, and inspect signal behavior in real time.

A key part of the project is Arduino integration: an Arduino UNO can act as a physical input/output bridge through a local Node.js agent.

What Works Today

Build and edit circuits

The current element library is split into three groups:

• basic logic gates (Buffer, AND, OR, NOT, NAND, NOR, XOR, XNOR)
• signal generators (Toggle, True Constant, False Constant)
• output/display elements (Lamp, 7-segment display)

Circuits are built by placing elements, connecting ports, and editing wires directly on the canvas.

Read signal states

Gately supports four signal states:

• True / 1 - green.
• False / 0 - gray.
• Z / Hi-Z - blue, used for disconnected inputs.
• X / error - pink, used when an output value is unknown or invalid.

Run the simulation

Simulation can run instantly or step by step with a delay. The logic engine runs in the background through a Web Worker, so circuit computation does not block the browser UI, even with cyclic connections such as triggers or oscillated NOR.

Try the Arduino bridge

The Arduino integration is an early MVP. It is rough and experimental, but tests show the core idea works: physical pin changes can drive virtual circuit signals, and selected virtual signals can be written back to Arduino pins.

Architecture & Project Layout

Gately is a pnpm/Turborepo monorepo with two applications and a set of shared packages:

• apps/web is the browser app, built with SolidJS, TypeScript, and Vite. It contains the user interface and the visual editor.
• The visual editor inside apps/web is built on top of AntV X6. It handles the graph canvas, nodes, ports, wires, and visual signal states.
• The logic computation happens on the client, but it is separated from the UI through a Web Worker. The main engine API lives in packages/engine, the worker bridge lives in packages/engine-worker, and supporting model/simulation code is split across packages such as packages/schema and packages/simulation.
• apps/arduino-agent is a local Node.js app. It talks to the web app through WebSocket and talks to Arduino UNO through Johnny-Five and FirmataStandard protocol.

Run Locally

For the web app, use a modern Node.js version supported by Vite. The project was tested with Node.js 24.11.1.

git clone https://github.com/markbrosalin/Gately.git
cd Gately
pnpm install
pnpm --filter web dev

Arduino is optional. The agent was tested with Node.js 18.20.8, because Johnny-Five has not kept pace with newer Node.js releases. Upload StandardFirmata to your Arduino UNO, connect the board, set ARDUINO_PORT if auto-detection is not enough, and start the local agent:

pnpm --filter arduino-agent dev

The default agent URL is ws://localhost:8787. Full setup guides live in the documentation.

Current Limitations

• No project persistence.
• No import/export workflow.
• No copy/paste workflow.
• No tab renaming.
• No editable element names or properties.
• Arduino integration is experimental.
• Not intended for production hardware control.

Documentation & License

Read the full guides in the Gately web-documentation.

Gately is released under the MIT License.