smolOS

Specialized Microcontroller-Oriented Lightweight Operating System

smolOS is a tiny (<20KB, <500LOC) and simple 🧪 research ⚙️ operating system ⌨️ written in 🐍 MicroPython for microcontrollers giving user a POSIX-like 📁 environment to play. It came with a set of 🧰 tools and 🪄 demos.

Background

What is an OS?

According to the Wikipedia: "An operating system (OS) is system software that manages computer hardware and software resources, and provides common services for computer programs.". In my own mind it's just an interface that helps user interacts with a computer. In that case smolOS is an operating system. In more precise definition it is a shell and a collection of scripts that works on top of MicroPython systems. Imagine command.com to the MS-DOS, bash to Linux. For the end user it really doesn't matter as long as it transforms a blank microcontroller into a working computer.

My first computer was 486 and a black and white CRT. I was using MS-DOS most of the time and get used to the command line interface. Now, some 25 years later I'm using Linux on all my computers and still prefer shell for basic stuff like editing, moving files or installing software. I wanted to keep that spirit in the smolOS.

Simplicity, Universality

Shell. It's not MS-DOS (command.com) nor bash equivalent, it's something in between. I wanted to keep all the commands user friendly. For example instead of UNIX ls and DOS dir I opted for list. From those three only the last says exactly what it does - lists files.

Files. Flat hierarchy. Microcontrollers have few MB of data at best. It's not a place to store documents it's a place to store few scripts to run our project. Having directories makes things more complicated, users get confused where they are and the whole ".." to go back was always strange. That's why there is no mkdir or cd.

System Overview

System should run on any MicroPython supported board but it's tested and developed on Seeed XIAO RP2040.

The whole system is in one file smolos.py. There are additional tools and demos that are optional.

Hardware Support

Real Life Use cases

smolOS Features

Additional Programs

All of those are for NeoPixel Grid 5x5 BFF:

Installation and Booting

Super Quick Guide

  1. Download latest sources from GitHub or smolOS-main.zip local mirror
  2. Put main system file smolos.py onto the board flash (that has latest MicroPython firmware)
  3. For auto-boot also copy main.py (optional but recommended)
  4. Restart device

Detailed Guides

Python firmware installation

System installation 

Connecting

$ picocom /dev/ttyACM0

Press ctrl+a+x to exit.

Running

First start. Or after flashing new main.py file. Restart the microcontroller:

>>> machine.soft_reset()

Automatic Boot (recommended)

If you copied the main.py after restart the device system should "boot" you into the smolOS. Like so:

Manual boot

If you put only smolos.py then you need to boot the system by hand.

In MicroPython REPL write:

>>> from smolos import smolOS
>>> os = smolOS()
>>> os.boot()

Using The OS

Help

Write help for quick reference.

List files

Edit a file

Simple text editor is build-in to the system.  

Forks

Articles

Tags

esp8266, micropython, os, operating-system, research-project, neopixels, xiao, micropython-esp8266, rp2040, seeeduino-xiao, seeed, esp