Disclaimer: I am not an expect in C, so I had Antigravity help me with the few changes I made. I only have an X3 device so I cannot confirm it works on other devices, but it should.
This is a personal fork of CrossInk which is based on CrossPoint Reader
Because I liked the changes from uxjulia, I mostly wanted to mess with the koreader sync engine. I admit it's pretty personal because I use Anx Reader for their cross-platform sync of reading, stats, highlights and annotations. I wanted to simplify my reading progress sync and Anx-Calibre-Manager has a koreader endpoint though it's API calls were different.
Before this modification, I had koreader app on my phone set to sync to both the official koreader sync endpoint and to my anx-calibre-manager koreader endpoint and I basically had to make sure it sycned to both whenever I switched devices and it got old fast. Anx-Calibre-Manager provides a koreader plugin you can install on devices that run it, but beccause these XTEINK devices are so underpowered they really just run the sync server and there was no way to load the plugin itself. And here we are. I don't plan to make any changes beyond this at this time, but for those of you that do use the same system feel free to take it and let me know if there are problems.
 Font: Bitter, Size: 12 pt, Margin: 15 |
 Reading Stats with custom front button mapping shown |
Note: This firmware is confirmed to be working on both the X3 and X4.
- New reader fonts: Lexend Deca and Bitter.
- Unicode emoji and miscellaneous symbols support (a limited subset).
- Adjusted font sizes: 8 pt, 9 pt, 10 pt, 12 pt, 14 pt, 16 pt, 18 pt, and 20 pt. See Font Build Variants for more details.
- Added
strikethroughsupport. - Made underlines thicker for better visibility.
- Added a custom
Minimaltheme and sleep screen option for the minimalists out there. - Added a custom
Dashboardtheme and sleep screen option for reading stats enthusiasts. - Added support for
<hr>section breaks. - Added support for "redaction" style rendering.
- Added improved support for tables with simple markup.
- Added ability to add bookmarks.
- Added ability to remap front buttons that only applies in the reader.
- Added Bionic Reading and Guide Dots as optional reader modes.
- Added Force Paragraph Indents for books that render as one giant wall of text.
- Added ability to pin a sleep image as a favorite. The favorited image will always be displayed when your sleep settings are set to
CustomorCover + Custom(when no cover is available). - Added more in-reader control remapping options for side buttons, short power button clicks, and long-press menu actions.
- Added ability to mark a book as finished from the in-book menu. A pop-up will also display once 99% of the book is reached. This status allows tracking of total books read.
- Added ability to move finished books to "Read" folder.
- In-book menu to quickly adjust reader options without having to exit the book.
- Reading stats: total books read, total reading time, number of sessions, pages turned, average session time, pages turned per minute. You can also set your reading stats as your sleep screen.
- All-time reading stats syncing between two CrossAnx devices.
- Reading progress sync between two CrossAnx devices.
- Added customizable Auto Page Turn Interval (anything between 5-120 seconds).
- Added ability to view Recent Books as a 3x3 grid view.
- To view a more detailed list for each version, visit the releases page to read release notes.
The default fonts have been replaced with Lexend Deca and Bitter. These fonts have been chosen specifically to improve reading fluency and e-ink performance. These 'sturdier' typefaces feature uniform stroke weights and open geometries, allowing the X4/X3 to render crisp, high-contrast text with font-aliasing on while significantly reducing ghosting and artifacts.
- Lexend Deca - A research-backed sans-serif typeface designed to improve reading fluency. Lexend was engineered based on the theory that reading issues are often a design problem (visual crowding) rather than a cognitive one.
- Bitter - A "contemporary" slab serif typeface for text, it is specially designed for comfortably reading on digital screens. The consistent stroke weight of Bitter helps it render particularly well on e-ink devices. The medium weight has been chosen specifically for improved rendering on the X4/X3.
The UI now uses Inter as the display font which has improved readability at smaller sizes.
- Support for a limited set of Unicode Emoticons and Miscellaneous Symbols using Noto Emoji and Noto Sans Symbols font.
There are 2 available build variants to choose from due to build size constraints: tiny, and xlarge.
See Font Build Variants for the full point-size and emoji-support matrix.
Reader Options, Bionic Reading, Guide Dots, Force Paragraph Indents, reading stats, and finished-book behavior are documented in Reader Features.
CrossAnx adds configurable button shortcuts.
See Controls for the full action list and defaults.
CrossAnx runs on an ESP32-C3 with limited RAM, so very large folders or complex EPUBs can be slower than they would be on a phone, tablet, or desktop app.
- Keep folders under about 200 files. For the smoothest browsing, aim for 50-100 files per folder.
- Having 1000+ books on the SD card is fine if they are split into smaller folders, such as by author, series, genre, or read/unread status.
- Avoid putting every book in the SD card root. The file browser has to scan and sort the current folder before it can show it.
- Text-first EPUBs are the best fit. Large image-heavy EPUBs, scanned books, comics, and omnibus files with thousands of sections may load slowly or fail under memory pressure.
- As a rough target, EPUBs under 20 MB tend to work the best. Files over 50 MB may still work, but they are more likely to be slow or memory-sensitive, especially if they contain many large images.
- If an EPUB is unusually slow, try optimizing it with the built-in web optimizer (via File Transfer) before copying it to the SD card: remove unused high-resolution images, split very large omnibus files, and avoid embedding multiple full font families when possible.
- Use a reliable SD card and leave some free space. CrossAnx stores settings, reading progress, cache files, stats, and generated book data on the card.
The device simulator renders the e-ink display in an SDL2 window so firmware changes can be sanity-checked without flashing hardware.
See Simulator for setup, platform notes, keyboard controls, and cache tips.
Download a firmware-*.bin from the releases page, then flash it with the web installer or command line.
See Installation for step-by-step flashing and revert instructions.
- User Guide
- Installation
- Font Build Variants
- Reader Features
- Controls
- Simulator
- Data Cache
- Web server usage
- Web server endpoints
- Common issues
- Project scope
- Contributing docs
CrossAnx uses PlatformIO for building and flashing firmware.
See Getting Started for prerequisites, clone setup, hooks, and validation commands.
Connect your Xteink X4 or X3 via USB-C and run:
pio run -e tiny --target uploadReplace tiny with another build variant if needed. See Font Build Variants.
See Testing and Debugging for serial logging, simulator checks, static analysis, and bug-report guidance.
The ESP32-C3 has about 380 KB of usable RAM, so CrossAnx stores reusable book and device data on the SD card instead of rebuilding everything in memory.
See Data Cache for the .crosspoint layout and File Formats for binary cache details.