Start here
Duet is early-alpha firmware for the Xteink X3 and X4. The current tester release is v0.1.0-alpha.7. Start by identifying your device, backing up the complete SD card, and keeping a known-good firmware BIN available for recovery. X3 and X4 firmware files are not interchangeable.
First Duet installation
- Read the current alpha notes and known issues.
- Back up the complete SD card, including hidden folders.
- Download the X3 firmware BIN or X4 firmware BIN. The complete alpha.7 release page also provides the combined firmware ZIP and SHA-256 checksums.
- Wake and unlock the reader, connect it by USB-C, and open the CrossPoint web installer.
- Choose the correct device, select Custom .bin, and flash the Duet BIN.
- After the restart, open Settings > System and confirm the displayed Duet version.
- Keep the backup and rollback BIN until the reader has passed sleep, wake, book-open, and page-turn checks.
The full installation guide includes command-line flashing and recovery details.
Updating an existing Duet installation
- Back up the complete SD card and keep the currently working BIN.
- Put exactly one new Duet BIN at the SD-card root.
- On the reader, open Settings > System > SD Firmware Update.
- Confirm the model and version, then allow the reader to restart.
- Verify the new version in Settings > System before removing the rollback copy from your computer.
Duet writes new state under /.duet and imports inherited CrossPoint/CrossInk state without deleting it. Do not manually move, rename, or delete /.duet, /.crossink, /.crosspoint, or /.crossink-stats-backup while upgrading; the legacy folders remain recovery sources.
Loading books and building the library
Copy supported books to the SD card in the folder structure you want to browse. Duet reads EPUB, XTC, XTCH, TXT, and Markdown files. The User Guide covers the reader, library views, search, More Info, bookmarks, clippings, statistics, sleep modes, and settings.
After copying from macOS, check the card’s book folders for AppleDouble metadata sidecars named ._*. A file such as ._Book.epub is not a second book, but its .epub suffix can make it look like one to a scanner. Remove only confirmed ._ sidecars, then verify the real EPUB count.
For large or multiply organized libraries, run Desktop Cover Prefill after loading books. It creates the exact X3/X4 grid and carousel thumbnails Duet requests, which avoids making the reader generate every cover during first browsing. The complete ready-to-paste prompt for Codex, Claude CoWork, Perplexity Computer, or another local assistant is included directly on that page and also available as a standalone prompt.
Plain EPUBs read normally, but true visible WPM and reference-page statistics require Duet word-location metadata. Run EPUB WPM Preparation once after adding new EPUBs, ideally on the source library before copying it to both readers. The combined AI Library Prep Prompt tells a local computer assistant to dry-run and back up the enrichment first, then run the correct X3/X4 cover prefill.
More Info descriptions and library categories use an optional Calibre-generated /.duet/state/library_catalog.tsv. Copying an EPUB to the SD card does not generate a description automatically; books remain readable without the catalog, but More Info shows only the metadata Duet can resolve locally. Spice/heat level is also optional personal metadata: leave it blank or omit it and Duet hides that field, removes its Reading Taste card, and leaves its achievements inactive. Fonts go under /fonts or /.fonts; StarDict dictionaries go under /dictionaries/<Name>/. Download the complete 123-family Duet font pack, install selected families through Settings > Reader > Font Options > Manage Fonts, or follow the upstream sources in the pack manifest. See Fonts for all options. For offline lookup, download the ready-to-copy WordNet 3.0 release asset and follow Dictionary Setup. Reader Features and the User Guide cover the rest of the library and reader structure.
Using an X3 and X4 together
Run the same Duet release on both devices. Nearby Position Sync compares the current book position and moves only after confirmation. Nearby Reading Stats Sync exchanges reading totals, per-book statistics, sessions, journals, dates, achievement milestones, and retained device snapshots. Protocol v6 requires a v6-capable build on both readers and does not pair with Alpha.7’s protocol v5 implementation. KOReader Sync remains available for remote book-position synchronization.
Position sync requires the same book identity on both readers. Achievement progress merges by highest milestone rather than replaying old popup notifications, so the ledgers can converge without both devices showing the same unlock alert at the same moment.
Testing the alpha
Use the short Alpha.7 Acceptance Quickstart for an ordered physical-device pass. The broader Alpha Testing guide lists known issues, high-value test areas, useful logs, privacy rules, and a copy-ready report format.
Use Alpha Test Report for a successful or mixed test session and Alpha Bug Report for one reproducible defect. Do not upload ebooks, full SD-card archives, credentials, personal catalogs, contact files, or raw reading history. Review logs before posting because book paths and filenames may be personal.
Recovery
If an update causes a boot loop, prevents books from opening, or breaks sleep/wake, remove the SD card and boot once. If the problem continues, flash the last known-good BIN through the web installer’s Custom .bin option. Do not delete /.duet, /.crossink, /.crosspoint, or statistics folders while diagnosing; they contain both recoverable state and useful evidence.
The Troubleshooting guide covers firmware recovery, SD-card filesystem checks, slow or missing covers, networking, and file transfer.
Where to go next
| What you need | Guide |
|---|---|
| Every user-facing feature | Complete Feature Tour |
| Source-verified feature counts and lineage | Feature and Lineage Catalog |
| Everyday controls and settings | User Guide |
| Installation and recovery | Installation and Troubleshooting |
| Current alpha risks and test targets | Alpha Testing |
| Preparing EPUBs for true WPM | EPUB WPM Preparation |
| Large-library cover preparation | Desktop Cover Prefill |
| Preparing EPUB metadata and covers with a computer assistant | AI Library Prep Prompt |
| Installing and using a dictionary | Dictionary Setup |
| Installing or converting fonts | SD-card fonts |
| All current screenshots | Alpha.7 Media Gallery |
| Contributing code or documentation | Contributing to Duet |
| Complete credit and audited upstream revisions | Third-Party Notices |