This is a JavaScript library that implementats the AVR 8-bit architecture.
It's the heart- but not the whole body- of the Arduino simulator at https://wokwi.com.
- Wokwi Arduino Simulator - Arduino simulator with a choice of hardware that can be wired up dynamically in your browser!
- avr8js-electron playground - a Downloadable Electron Arduino simulator app
- AVR8js-Falstad - combining the Falstad circuit simulator with AVR8js!
- The Engineering Physics Department of Dawson College's Arduino Course - an introduction to Arduino with a focus on robotics
This library only implements the AVR CPU core. You have to supply it pre-compiled machine code to run, and implement functional simulations of any external hardware. You will probably also want to add audio/visual representations of external hardware being simulated.
A rough conceptual diagram:
Pre-Compiled machine code --> AVR8js <--> Glue code <--> external hardware functional simulation <--> simulation state display for the user
You may be interested in exploring the wokwi-elements collection of web-components for visual representations of many common hardware components. (Note: these are visual only elements- you will need to add the appropriate functional simulation and glue code.)
A step-by-step video tutorial showing how to build a simple Arduino simulator using AVR8js and React:
And a related blog post.
These examples show working examples of using avr8js in an application. Many of them also demonstrate how to use the wokwi-elements and include working examples of functional simulations of the components, and how to hook them up to avr8js.
- Minimal Example
- 6 LEDs
- LED PWM
- Serial Monitor
- NeoPixel Matrix
- Arduino MEGA NeoPixel Matrix
- Simon Game - with pushbuttons and sound
- XMAS LEDs
- Assembly Code
- EEPROM persistence
Note: they are all hosted outside of this repo.
The demo project allows you to edit Arduino code, compile it, and run it in the simulator. It also simulates 2 LEDs connected to pins 12 and 13 (PB4 and PB5).
To run the demo project, check out this repository, run npm install and then npm start.
The library focuses on simulating the ATmega328p, which is the MCU used by the Arduino Uno.
However, the code is built in a modular way, and is highly configurable, making it possible to simulate many chips from the AVR8 family, such as the ATmega2560 and the ATtiny series:
Check out issue 67 and issue 73 for more information.
Run the tests once:
npm test
Run the tests of the files you modified since last commit (watch mode):
npm run test:watch
For more information, please check the Contributing Guide.
Copyright (C) 2019-2025 Uri Shaked. The code is released under the terms of the MIT license.