Arduino, running the sketch you wrote

arduino-cli compiles it, an AVR8 core executes it instruction by instruction, and the LCD shows what the ATmega328P actually put on the bus. Uno, Nano, Mega and ATtiny85, no board on your desk.

Open the editor

Your firmware, on an emulated CPU

arduino-cli or ESP-IDF compiles the sketch, then AVR8, RP2040, RISC-V, Xtensa or ARM executes it instruction by instruction. What the OLED draws and what the serial monitor prints is what the chip actually did.

Open the editor

Analog that is solved, not faked

ngspice compiled to WebAssembly runs a full nodal analysis about 60 times a second. GPIO pins drive real nets, ADC inputs read solved node voltages, and probes report RMS, DC and current wherever you drop them.

SPICE simulator

Digital logic, gate by gate

Adders, comparators, decoders, flip-flops and a 1-bit ALU slice: no microcontroller anywhere, just gates, switches and LEDs solved as a real net. The classroom half of electronics, without the breadboard.

Digital examples

The partner boards, emulated for real

The M5Stack Cardputer with its keyboard, Seeed's round display keeping time, Pimoroni's Badger 2350 driving e-paper, and DFRobot's UNIHIKER M10 in the catalogue alongside them. Their makers sent the hardware so the emulation could be checked against the real thing.

See every board

rsetyo-widayanto on Velxio

Public circuit and Arduino simulations by rsetyo-widayanto. Open a project to edit the code, wire up components and run it free in your browser.

XIAO ESP32S3 NeoPixel Rainbow Ring — Xiao Esp32S3 Sense — NeoPixel rainbow animation on a 26-LED ring driven by XIAO ESP32S3 Sense via DIN on GPIO1.

Two RGB Rings and WS2813 Strip - Yellow Light — Xiao Esp32C6 — Project to light up two Grove RGB LED Rings and a Grove WS2813 LED Strip in yellow.

XIAO S3 Battery Gauge on Round Display — Xiao Esp32 S3 — Battery voltage gauge using Seeed Round Display with arc indicator on XIAO ESP32-S3.

ESP32 7x72 NeoPixel Matrix Display — ESP32 — A large 7x72 NeoPixel matrix display controlled by an ESP32.

NeoPixel Matrix Animation Debug — ESP32 — Merangkum alasan animasi tidak tampil pada matriks NeoPixel.

XIAO ESP32S3 Sense dengan LED Ring RGB — Xiao Esp32S3 Sense — XIAO ESP32S3 Sense dengan Seeed Round Display dan LED ring 26 pixel untuk efek running RGB

ESP32 Animation Switcher — ESP32 — An ESP32 project with an ILI9341 display and a button to switch animations.

Unicorn Matrix Animasi — ESP32 — ESP32 mengendalikan NeoPixel matrix 7x72 dengan tombol ganti animasi.

Mata Robot 72x7 Animasi — ESP32 — Matriks NeoPixel 72x7 menampilkan sepasang mata robot merah dengan animasi buka, melirik, kedip, dan strobo.

Animated Eyes on 72x7 Matrix — Esp32 Devkit C V4 — Two animated eyes on a 72x7 NeoPixel matrix driven by an ESP32, with a button to restart the animation cycle.

Arduino, ESP32 & Raspberry Pi.
Right in your browser.

Hardware partners

Real silicon. Real physics. One canvas.

Arduino, running the sketch you wrote

Your firmware, on an emulated CPU

Analog that is solved, not faked

Digital logic, gate by gate

The partner boards, emulated for real

Every architecture.
One tool.

Bring Velxio into your course.

Pro for every student

One predictable bill

The tools they will use at work

Free to run circuits. Pay for more boards, with or without AI.

Connect with the open source community

rsetyo-widayanto on Velxio