A love letter to minimalism.

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EROS

A deliberately minimal Cover Flow firmware for the TrimUI Brick. One single row of cards - your game systems and a music app - and nothing in the way. No network, no scraping, no settings screens, no chrome. Turn it on. Play.

EROS was made for personal use. If you like it too, that's great, but thank you in advance for not opening PRs or Issues.

What it is

• Cover Flow launcher: a single perspective-tilted row with reflections. Pick a system, drill into its games, pick a game - it launches minarch with the right core and auto-resumes where you left off.

See browsing systems

See drilling into a system's games

• Muse: a built-in music player that slots in as a card. Browse albums as a Cover Flow, drill into tracks, focused now-playing screen. Playback runs in a small daemon, so the music keeps playing while you close the app and browse - and right on into a game: start one while music's playing and it launches silent, so the music carries straight through.

See Muse - albums, now playing, modes

• Made to disappear: a dark monochrome in-game menu - the one bit of chrome is a low-battery dot. It's meant to feel like hardware, not software.

Install

Copy the contents of the release (or out/sd/ if building from source) onto a FAT32 SD card, insert it into a stock Brick, and power on. On first boot EROS installs its boot hook and comes straight up.

Build

Needs Docker - the tg5040 cross-toolchain runs in a container.

make                          # -> build/eros.elf   (the launcher)
make -f apps/music/cross.mk   # -> build/muse       (the music player)
minarch/build.sh              # -> vendor/minarch.elf (EROS-restyled, from NextUI source)
mk/fetch-vendor.sh            # pull cores + libs from a NextUI release into vendor/
mk/payload.sh                 # assemble the installable SD payload under out/sd/

On the card

/mnt/SDCARD/                          ← FAT32 SD card root
│
├── eros/                             the firmware itself
│   ├── eros.elf  muse  minarch.elf   launch.sh
│   ├── systems.cfg  eros.cfg         ← the only "settings"
│   ├── icons/                        one PNG per card (named in systems.cfg)
│   ├── cores/  lib/                  libretro cores + runtime libs
│   └── EROS-boot.mp4  splash.png     boot animation + splash
│
├── Roms/
│   ├── NES/                          cartridge system → one file per game
│   │   ├── Contra (USA).zip
│   │   └── .media/
│   │       └── Contra (USA).png      ← box art; filename matches the ROM
│   │
│   └── PlayStation/                  disc system → one folder per game
│       ├── Crash Bandicoot/          single disc: just the disc files
│       │   ├── Crash Bandicoot.cue
│       │   └── Crash Bandicoot.bin
│       ├── Final Fantasy IX/         multi-disc: discs + an .m3u inside
│       │   ├── Final Fantasy IX (Disc 1).cue   (+ .bin)
│       │   ├── … Disc 2-4 …
│       │   └── Final Fantasy IX.m3u  ← lists the discs by bare name
│       └── .media/
│           ├── Crash Bandicoot.png   ← named after the folder
│           └── Final Fantasy IX.png
│
├── Music/
│   ├── <Artist>/<Album>/             one folder per album (tag-driven)
│   │   ├── 01 - Track.ogg            WAV / MP3 / FLAC / OGG
│   │   └── cover.png                 ← album art (or folder.jpg)
│   ├── Playlists/                    curated collections
│   │   └── Road Trip/                folder name = label, filename order
│   │       └── 01 first.mp3          cover.png optional; else a branded cover
│   └── loose-track.mp3               files loose in Music/ → a "Singles" bucket
│
├── Bios/                             only the few systems that need one
│   └── PlayStation/
│       └── scph5501.bin              ← you supply it if needed (copyrighted)
│
└── Saves/  .userdata/                save files + states (auto-created)

ROMs go in any folder you like - map each to a card in systems.cfg. Cartridge systems are one file per game; disc systems (PlayStation, and any future Saturn / Sega CD) are one folder per game, with an .m3u inside for multi-disc titles. BIOS is needed only for PlayStation (a real scph*.bin) and optionally GBA (gba_bios.bin) - every other system runs without one. See Artwork for box and album art.

Two tiny config files are the whole "settings" surface:

• systems.cfg - one line per card: kind|name|folder-or-exec|core|icon.
• eros.cfg - Bluetooth sink MAC, default volume/brightness, startup card.

WiFi is never brought up; Bluetooth audio auto-connects at boot if configured.

Artwork

All art is drop-in and warmed at load, so scrolling never hitches on a decode:

• Game box art - Roms/<system>/.media/<rom-name>.png, where <rom-name> is the ROM's filename without the extension, matched exactly. Multi-disc games use the folder name.
• Album art - cover.png (or folder.jpg) inside each Music/<artist>/<album>/ folder. Muse warms the whole album-cover cache on open.
• System icons - eros/icons/*.png, referenced by systems.cfg.

Sizes. The panel is 1024×768, so nothing ever draws larger than that - keep the longest side ≤ 768px. Bigger is invisible on-screen and only costs decode time and memory (it's the difference between a smooth scroll and a first-move stutter):

Asset	Recommended long side	Format
Box art / album covers	~512–768px (a card draws at ~365–515px)	PNG or JPG
System icons	768px	PNG, transparent background

Where to get it:

• Box art - libretro-thumbnails (repos/packs) are named to match No-Intro ROM names, so they drop straight into .media/. SteamGridDB has high-res custom covers; EmuMovies has curated sets.
• Album art - the Cover Art Archive (MusicBrainz), Discogs, or whatever's embedded in your files' tags.

The manual in its entirety

Cover Flow

• A in, B out
• Volume buttons - volume, any screen
• Function buttons - brightness, any screen
• Power - power off, any screen

That's the whole grammar - the rest is detail.

Muse

Albums are a Cover Flow of their own; a chosen album opens as a track list.

• X - jump to Now Playing whenever something's playing
• Now Playing:
  • A - play / pause
  • Left / Right - previous / next
  • L1 / R1 - seek -5s / +5s
  • X - cycle modes
  • Y - stop
• MENU - background Muse and return to Cover Flow

Bluetooth

Flip the side switch to BT. A known headset reconnects on its own; otherwise a pair screen takes over:

• X - scan
• A - pair and connect
• B - dismiss

It closes itself the moment a device connects. With the switch on BT, audio routes to the headset - both Muse and in-game audio (a game carries the usual Bluetooth latency; flipping back to the speaker is instant). Once paired, the headset's own buttons drive Muse: one press play/pause, two next track, three previous track.

In a game

EROS uses a slightly modified version of NextUI's minarch - MENU opens its in-game menu, and its button mapping lives in that menu's own settings, so you're on your own in there. Two EROS things hold everywhere: function buttons for brightness, and Power powers off (and saves your spot).

Code

src/ is a compact SDL2 app: coverflow.c (perspective cards + reflections), config.c (two small parsers), platform.c (tg5040 display / input / exec), main.c (screens + launch loop). apps/music/ is Muse (UI, library scan, and the audio daemon). It's 0BSD - do whatever you want with it.

Built with

• minarch and the libretro cores are built from NextUI source (GPLv3) and keep their own licenses - cores carry their individual terms (note: the bundled snes9x core is non-commercial).
• Muse's audio decoder dispatch is adapted from DiscoBoy (MIT, Utility Muffin Research Kitchen); decoding uses the public-domain single-header decoders dr_wav / dr_mp3 / dr_flac (mackron) and stb_vorbis (Sean Barrett).
• The menu/logo typeface is Josefin Sans (SIL Open Font License).