Ralsina.Me

ESP-Osito News for June 6, 2026

Roberto Alsina — Sat, 06 Jun 2026 15:00:00 GMT

OTA Updates in the Settings App

The Settings app now includes a System section with:

Current firmware version display
Update check action
Firmware update action

This will download the latest firmware and install it. Alternatively you can download a firmware to /system/firmware.bin in the SD card and reboot.

App Management

Also, there is now a "Apps" tag in the settings app. Currently you can only use it to uninstall apps, but more is planned.

Reader App

Better progress saves! More reliable and consistent.

ESP-Osito News for June 4, 2026

Roberto Alsina — Thu, 04 Jun 2026 15:00:00 GMT

Shell App: A Command Line for Esposito

The latest addition to the app roster is a shell — a simple command-line environment running in text mode on the 320x240 display. It supports ls, cd, cp, and mv as builtins, and any two-token command that isn't a builtin is treated as <app> <file>, launching Esposito apps directly from the command line.

It features inline line editing with cursor movement (Fn+A/D), history navigation (Fn+W/S), Ctrl+U to clear the line, and Ctrl+L to clear the screen. The current working directory is displayed in a status bar and persisted across sessions through the config API, along with up to 20 history entries.

The shell is deliberately barebones — no pipelines, no redirection, no tab completion, no variable expansion. What it does provide is the right foundation to add those things later.

Wireless Keyboards For All Your Projects

Roberto Alsina — Thu, 04 Jun 2026 14:55:38 GMT

When you are starting a new electronics project, you often need a bunch of controls to trigger things. Like, you want to have 4 or 6 or 10 buttons to do things.

This puts you in a complicated position because it means you need to build a thing before you know if the thing is worth building. Wiring 10 buttons is a lot of work! so let's not do that.

Using bt2i2c then anything that can talk I2C (and that is a very low bar!) can use a full wireless keyboard, as long as you connect three pins!

The basic concept is:

Get a Pico W
Get a Screen (optional, but useful)
Get a cheap BT keyboard (classic or BLE, both work)
Get the bt2i2c firmware onto the Pico W
Connect your project to the Pico W via I2C

Then, on your project side, use the client for the BBQ20 or BBQ10 keyboards from solder party.This is (supposed to be) 100% compatible!

And that's it, you get keys via I2C, and can control your new project at will.

The screen will show you when it's scanning, or connected, or if you need to type a PIN. If you don't have a screen, use the pico's USB serial port.

Dead World (Convergence Book 6)

Roberto Alsina — Thu, 04 Jun 2026 00:00:00 GMT

Author: Craig Alanson
Rating: ★ ★ ★
See in goodreads

Review:

I can't get over how Alanson is rewriting his skippy books as fantasy.

ESP-Osito News for May 31, 2026

Roberto Alsina — Sun, 31 May 2026 15:00:00 GMT

Peanut-GB: Game Boy Emulation on ESP32

Yes, really. The ESP32 CYD is now a Game Boy. Peanut-GB is a DMG emulator running as an Esposito app, achieving 40-60 FPS at 240MHz with no PSRAM.

ROMs are loaded from the SD card into flash memory and memory-mapped for fast access. The 160x144 Game Boy display is centered on the 320x240 screen with black borders, just like the real thing.

Controls

Action	Key
D-Pad	W/A/S/D
A Button	L
B Button	M
Select	O
Start	P
Save State	K
Load State	J
Exit	ESC

ROMs go in /sdcard/roms/ on the SD card. For legal homebrew Game Boy games, check out Homebrew Hub.

Sprite API and Flash ROM Loading

To make the emulator possible, the firmware gained two new systems:

Sprite API: Paletted sprites for efficient pixel-level rendering. The Game Boy display uses a 2bpp sprite (5.7KB on system heap instead of a 23KB RGB565 buffer), with one sprite_write_row call per scanline.
Flash ROM loading: ROMs are copied from SD card into the app_code flash partition and memory-mapped. This gives zero-overhead pointer dereference instead of slow SD card I/O during emulation.

Improved Event Handling

The OS event loop now drains all pending events instead of processing one per iteration. This eliminates the input lag that was especially noticeable in fast-paced apps like the emulator. The event queue was also doubled from 32 to 64 slots.

CPU at 240MHz

The CPU frequency was bumped from 160MHz to 240MHz, which — combined with compiler optimizations and bank 0 RAM caching — is what makes Game Boy emulation viable on this hardware.

Credits

The emulator core is Peanut-GB by Mahyar Koshkouei, a remarkably fast single-header C99 Game Boy DMG emulator library. Licensed under the MIT License.

ESP-Osito News for May 30, 2026

Roberto Alsina — Sat, 30 May 2026 15:00:00 GMT

Color Palettes!

Settings now has a Palette option that lets you cycle through four color themes: CGA (classic), CGA Light, Solarized Dark, and Solarized Light. The choice is saved and applied at boot, so your preferred look persists across restarts.

Also, all button labels are now bold bright white for better readability.

Portrait Mode Fixes

The paint app and the Arduboy compatibility layer (used by the Numbers game) were both broken in portrait orientation. The graphics buffer was using the physical screen dimensions (320x240) instead of the rotated dimensions (240x320), causing garbled drawing, invisible palettes, and off-center rendering. All fixed now — everything works correctly in both landscape and portrait.

Screenshots of Graphics Apps

Pressing Fn+ESC to take a screenshot now works for graphics-mode apps (paint, Arduboy games). Previously only text-mode screenshots were captured, and graphics apps would produce all-black images.

ESP-Osito News for May 29, 2026

Roberto Alsina — Sat, 30 May 2026 02:29:42 GMT

Got published on Hackster and Hackaday!

Thanks to both sites for the nice words:

Hackaday
Hackster
I admit I posted this on reddit too

Dynamic Fonts!

Fonts are tricky in embedded platforms. There are many formats, some are monochrome, others are "smooth" because they support transparency, and you have to choose what characters the font includes.

You can embed the font in your binary, which is slightly annoying and means the font uses space in flash, which is limited.

Or you can ship multiple fonts and load them from somewhere, be it flash or the SD card. But normally that means you load it into RAM, which is even more limited!

Usually this means you ship one font.

Well, no. I want ESP-Osito to be good and user-friendly. It's already bad enough that we only support monospaced fonts!

So, I implemented a way to load sets of fonts called packs (for example: regular, bold, italic, bold-italic Hack 9pt) from the SD card, which is essentially infinite, to flash.

This uses a fixed amount of flash (larger than your larger font, maybe 400KB) but you can have as many fonts as you want as long as you only use one pack at a time!

So now ESP-Osito ships with:

Hack
IBM Plex Mono
Inconsolata
Ioskeley
Kode Mono
Nova

Toolbar Widget

I added a toolbar widget to the ui library. It automatically and tastefully arranges buttons in a row. Then I went to town with it, and used it everywhere. The on-screen-keyboard? Toolbars. The Calculator? Toolbars. Most screens in most apps? believe it or not, also toolbar!

This made apps simpler, more powerful, and more consistent

App Fix and Improvements

Too many to count, file manager is now touch friendly, all screens that would not run properly without a keyboard now should work fine with touch only.

Got a new 3d Printer!

So I am making improved versions of the cases. I will probably publish them on printables soon.

ESP-Osito News for May 27, 2026

Roberto Alsina — Wed, 27 May 2026 20:01:15 GMT

The ebook reader now has a bookstore

You can go to https://esposito.ralsina.me/books.html and pick any of 100 books. Plug your device via USB, open the ebook reader, click "get" in the book list, then click the download icon on the book. The book automatically downloads to the device!

This is mostly intended as a testbed for delivering "stuff" to the devices, like an app store or anything else. But in the meantime, hey, books to read!

Better Unicode Support

Previously most things were ASCII only. Now full unicode support is there. The limitation is that a full unicode font would not fit so I added all the normal latin characters, plus some symbols we can use for better UI, so we can show "▼" rather than write "DOWN" in a button.

Also, of course, this makes the ebook reader look a lot better with better quote characters, en or em-dash, accented characters and so on.

ESP-Osito: a useful operating system for the cheapest computer

Roberto Alsina — Mon, 25 May 2026 18:49:55 GMT

Moore's law says for the same money you get twice the computer every 18 months. That should also mean that you get the same computer for half the money. Sadly that is not true, and you need to wait around 40 months. But this means that at some point the worst computer you can buy is going to be fast.

I think that time has come. The cheapest computer you can buy is a $10 Cheap Yellow Display which is about as powerful as a "good" computer from 1992. And I decided I was going to treat it as a real computer and not as a toy. So I wrote ESP-Osito which tries to be a real operating system for it.

You can learn more about it at its own website of course but here's some highlights.

It has apps. It has settings. It has networking. It has THE game (snake). It has a text editor. It has an ebook reader. You can install apps. You can do things with it, because this is a real computer.

It's also hundreds of times slower than your cellphone, so it has limits, but if we write software for the hardware we have ... things happen. Like:

Apps start in milliseconds
The OS boots in under a second
Things are pretty snappy
Apps remember their state, so even without multitasking you just ... switch? And it works?
Apps have a simple API exposed to them, so they are not terribly hard to write
There are few resources but ... it's enough?

It honestly feels kinda retro, from a better, more fun era. It is sort of reminiscent of palm pilot (no multitasking, app checkpoints, touchscreen) and of 80s home computers (text and graphics modes) and of unix/linux (terminal mode)

And it's fun to think of hardware combinations. I can add a keyboard. Or not. I can control things via pins (this is a microcontroller!) Or not. It's cheap, in the way Raspberry Pis are not anymore, now that they are simply not-great PCs with pins.

Add a 3d printer and ... hey, that looks blackberry-ish!

Or like a Pebble!

Or ... something!

What I need now is people trying it. People making it work in other hardware. People writing apps. People just checking it out.

Hope I find some!

The Lost Bookshop

Roberto Alsina — Mon, 25 May 2026 00:00:00 GMT

Author: Evie Woods
Rating: ★ ★ ★ ★
See in goodreads