Technical EPUB support
Tables with captions and colspan, image-based formulas, figures, headings, nested lists, blockquotes, emphasis, Greek symbols, and exact fragment targets.
- EPUB 2 + EPUB 3
- Four-tone images
- Inline formulas
Open-source firmware · Xteink X3
Technical books deserve better firmware.
Tables stay structured. Formulas stay legible. Books open before they finish decoding.
- Target
- ESP32-C3
- Memory
- 256 KB heap
- Panel
- 792 × 528
- Engine
- Async + cached
01 / TRY BEFORE FLASHING
Try the reader before you install it.
The emulator runs the same deterministic application state machine as the firmware. Browse a library, open a technical EPUB, and test the controls without touching your X3.
Launch live emulator ↗
ACTIVITY readerROTATION portraitREFRESH fast
02 / THE READING ENGINE
Built for the pages that break other firmware.
Ferris Reader treats technical material as first-class content—not an edge case.
528 px
792 px
03 / READER CAPABILITIES
Technical books are the baseline.
Concrete support across parsing, layout, navigation, display, and reopen.
Resume-first loading
The saved section becomes readable first. Nearby pages and the remaining book decode afterward in bounded background slices.
EPUB contents and targets
Nested chapters, breadcrumbs, page jumps, current-chapter feedback, and links to exact EPUB fragments.
SD-card library and cache
Folder browsing, recent books, per-book progress, missing-file cleanup, and cached reopen.
X3 e-ink rendering
Reading refreshes, periodic ghosting scrubs, four image tones, text smoothing, sleep/wake, clock, and battery status.
Fonts, keys, and refresh
Four font sizes, front-button remapping, refresh cadence, image tones, inactivity timeout, and boot orientation.
Emulator and device checks
The same deterministic Rust application core runs in the browser emulator and on the X3. UI snapshots cover rendered pixels; hardware benchmarks cover the device.
04 / MEASURED ON THE GLASS
No synthetic victory laps.
Same X3. Same SD card. Same technical EPUB. User-visible timings over repeated runs.
BENCHMARK PLAN / TTFRDeep-book resume → readable pixels
DATA PENDING
0time to readable page →MAX
Stock XteinkBenchmark
CrossPointBenchmark
Ferris ReaderBenchmark
Bars are layout placeholders—not performance claims. Final results will publish firmware versions, cache state, median, and range.
05 / ASYNC DECODE PIPELINE
Start reading now.
The rest catches up.
Work is split into bounded slices. The foreground stays responsive while Ferris builds a reusable SD-card cache behind it.
ONE CORE / ASYNC PIPELINEReadable first. Then decoding keeps advancing behind the page.
FOREGROUND ALWAYS GOES FIRST01OPEN BURSTforeground priority
OPENRead package→
RESUMESection 21 text→
TTFRReadable page
FOREGROUNDYou start reading
PAGE PRESENTED↓ BACKGROUND LOOP STARTS HERE ↓YIELDS ON INPUT
02 → ∞BACKGROUND LOOPkeeps advancing
05…
194204
212IMAGES
223233243↑ INPUT / YIELD253263
…END5
- 1 Saved section text → readable
- 2 Saved-page images
- 3 ~5 pages forward
- 4 ~2 pages back
- 5 Remaining book → SD cache
YOU KEEP READING WHILE THE LOOP ADVANCES. Input pauses the current slice, gets the foreground, then background decoding resumes where it stopped.
06 / ACTIVE DEVELOPMENT
Next on the drawing board.
Xteink X4
Emulator support exists. Physical-device validation and the grayscale driver are in progress.
Wi-Fi + Calibre
Wireless library syncing through a companion Calibre plugin is under development.
07 / WEB FLASHER
From browser to book
in one cable.
Connect an unlocked Xteink X3 over USB-C. The installer verifies compatibility before it writes anything.
Locked device?The installer refuses to flash. Ferris Reader does not yet provide a safe recovery path for USB-locked units.
FERRIS FLASH / WEB SERIALSECURE STATE: IDLE
01Browser checkWeb Serial availableREADY
02Connect X3USB-C data cable · device awakeWAITING
03Verify + installUnavailable until device check passesLOCKED