Posted by dmcrespo 11 hours ago
A free, open-source emulator for 19 embedded boards: Arduino, ESP32, Raspberry Pi, RISC-V , running real compiled code in your browser.
The best part: it's fully local.
No cloud dependency. No student accounts. No data leaving your network. Self-hostable with a single Docker container.
Universities and bootcamps can deploy it on their own servers and give every student access to a complete embedded development environment, for free.
I've been working on this for over a year, and just shipped v2.0 with ESP32 emulation (via QEMU), a custom RISC-V core, and Raspberry Pi 3 support that runs real Python
Does your editor do this? I tried the example but didn't see e.g. LEDs blinking
It also provides a more visual and interactive environment (editor, peripherals, simulation controls), which is especially useful for teaching and for beginners.
The Docker image is there so you can easily install it on your own machine if you want to run it locally or work on development
Anyway, seems like a pretty cool project - congrats!
I used a little AI to create the graphical interface since I focused heavily on emulation, testing, and refining and optimizing the circuit editor. But now I have plans to improve the UI and make it faster and more intuitive
Still a lot to improve there, but glad it’s useful already
A lot of simulators stop at simple sketches, but the goal with Velxio is to support more realistic workflows , multiple boards interacting, real toolchains, and more complex setups
Still early, but definitely moving in that direction
What's new in v2:
- 19 boards across 5 CPU architectures (AVR8, Xtensa, RISC-V, ARM Cortex-M0+, ARM Cortex-A53) - ESP32 emulation via QEMU (lcgamboa fork) — real flash images, ROM function emulation, GPIO/ADC/timers - ESP32-C3 and CH32V003 run on a custom RISC-V core written in TypeScript, entirely in the browser - Raspberry Pi 3B via QEMU raspi3b — boots real Pi OS, runs Python - Realistic sensor simulation: DHT22 (40-bit protocol timing), HC-SR04 (trigger/echo), WS2812B NeoPixel (GRB decoding) - 48+ electronic components from wokwi-elements
Architecture:
- AVR, RP2040, and RISC-V emulation runs client-side (avr8js, rp2040js, custom TS core) - ESP32 Xtensa and Pi 3 run on backend QEMU - Compilation via real arduino-cli - React + Vite frontend, FastAPI backend - Self-hostable via Docker, no account needed
Source: https://github.com/davidmonterocrespo24/velxio (AGPLv3)
Happy to discuss the emulation architecture — particularly the trade-offs between in-browser vs. backend QEMU emulation
I look forward to trying this out though, great project!
If anyone still has issues accessing velxio.dev, let me know
Really awesome project, it runs well on my old android phone, the fact that I can use a tool like this on my phone is pretty wild, you have done well with the UI in that regard. The oscilloscope is a really nice feature too.
And glad you liked the oscilloscope, that was a fun one to build.You can select the motherboard and ping you want to monitor.
Things are more stable now, but still tuning performance under load
If anyone finds it useful, the source is here: https://github.com/davidmonterocrespo24/velxio
Always happy to get feedback or contributions.
Can this project help me in any way during dev stage before uploading the code to device just to see it doesn’t work ? Eg could I use this to somehow compile&run those esphome yamls via this emulator?
It’s still exploratory, but it could definitely go in that direction
I tried to make it as close to zero-setup as possible so people can just jump in and experiment
I also integrated a couple of existing open-source emulators, like the Raspberry Pi Pico and Arduino ones. And I even reached out to the creator of Wokwi to share the project.
In terms of differences, one of the biggest ones is that Velxio supports multiple heterogeneous boards in the same circuit: for example, two Arduinos connected over SPI or serial, ESP32 with Arduino, Raspberry Pi 3 with a Pico, etc.
Another major difference is the focus on full emulation, including ESP32 (via QEMU) and a Raspberry Pi 3 running Linux (still in beta).
There are also quite a few other differences, but those are probably the most notable ones
One suggestion: The main splash screen image is nearly 8MB big. It takes a noticeable time to download on my connection. I'm not sure what bandwidth costs these days, but seems like that could be something to optimize.