Velxio is an open-source Arduino emulator that runs entirely in the browser.

The project allows users to write Arduino sketches, compile them using arduino-cli, and simulate microcontroller hardware using real CPU emulation.

The emulator currently supports:

• Arduino Uno (ATmega328p)
• Arduino Nano (ATmega328p)
• Arduino Mega (ATmega2560)
• Raspberry Pi Pico (RP2040)

Key features:

• AVR8 CPU emulation using avr8js
• RP2040 emulation using rp2040js
• 48+ interactive electronic components
• Monaco-based Arduino code editor
• Serial monitor with UART emulation
• Hardware peripheral simulation (GPIO, SPI, I2C, ADC, PWM)
• Arduino library manager
• Self-hosting via Docker

The goal of the project is to provide a fully open-source environment for experimenting with Arduino circuits and understanding how microcontroller emulation works internally.

Live demo:
https://velxio.dev

Source code:
https://github.com/davidmonterocrespo24/velxio