u/nilseuropa

A couple of months ago I stumbled across the Waveshare ESP32-S3-RLCD-4.2 board. The moment I saw it I knew I had to build something with it.

The display is fast, crisp, low-power, and actually readable in direct sunlight. It has that early-2000s PDA vibe that immediately appealed to me. Under the hood there's an ESP32-S3, stereo microphones, an audio DAC, PSRAM, and enough I/O to make it much more than just another dev board.

What I didn't want was yet another tiny Linux distribution struggling on limited hardware. The ESP32-S3 is a capable MCU, but it's still an MCU. Running a full Unix userspace just to launch a terminal felt like the wrong tradeoff. ( No offense, all my respect goes to whoever did that already on this metal. )

Instead, I wanted firmware that boots instantly, stays responsive, and does useful work without dragging around decades of operating system baggage. Like a true Pocket Computer from my childhood.

So I started writing Solar OS.

It's built on top of ESP-IDF and FreeRTOS, but the goal isn't "yet another RTOS application." The architecture is designed to grow into a real operating system while remaining lightweight enough for embedded hardware.

Some of the ideas behind it:

Modular services instead of a monolithic application.
A message-based architecture so components remain loosely coupled.
Native applications instead of web apps.
A shell that isn't an afterthought.
A graphics/UI stack designed for this hardware rather than ported from desktop systems.
Fast boot, deterministic performance, and low power consumption.

One design goal from the beginning was to make the system highly scriptable. Both Lua and Python are first-class citizens, and instead of exposing hardware directly, scripts communicate with system services. Whether it's drawing on the display, playing audio, accessing the filesystem, talking over Wi-Fi or Bluetooth, or using peripherals, everything goes through well-defined service APIs. That keeps applications portable, secure, and easy to extend while still allowing low-level native applications where performance matters.

The immediate goal is to cover the things I actually use every day: ssh client, chat, text reader, distraction free editor and a few developer tools.

Beyond that, I'd like it to evolve into the kind of computer we used to take for granted: turn it on, it boots under a second, everything is local, every application is native, and you can actually program the machine you're holding. Lua and Python make it easy to automate tasks, while native applications provide unrestricted access to the platform when performance matters.

Whether it ends up being an extendable pocket terminal, a development platform, or just an excuse to explore operating system design, I'm having a lot of fun building it.

The project is still in its early stages, but it's already becoming a fun experiment in operating system design.

One thing I could really use help with: I absolutely suck at 3D design. The enclosure I have works, but it's far from pretty. If anyone enjoys CAD or product design and would like to help create a nicer 3D-printable case, I'd love to collaborate.

Repository: https://github.com/nilseuropa/solar_os

I'd be interested in hearing what features people would actually want from a handheld embedded OS like this.

If you had one in your pocket, what would you expect it to do?

SolarOS 4.1.0

SolarOS