Custom firmware for the Xteink X4 e-paper device. Turns a $70 e-ink reader into a smart device with wireless tools, security features, communication, games, and utilities — while keeping full e-reader functionality.

Forked from CrossPoint Reader. All core reading functionality comes from CrossPoint. Biscuit builds on top of it.

Biscuit treats the Xteink X4 as a general-purpose smart device, not just an e-reader. The home screen is a tile-based dashboard with live system info (battery, heap, uptime, WiFi status). Reading is one of eight categories, not the main focus.

The 4.26" e-ink display is readable in direct sunlight, retains its image without power, and gives the device days of battery life. Seven physical buttons provide navigation without a touchscreen. WiFi and BLE 5.0 enable wireless tools. A MicroSD card stores everything.

The home screen is a dashboard of eight tiles. Everything lives under one of them.

All apps in Recon are read-only — they listen but never transmit.

Offense opens a 2×2 sub-menu grouped into four phases. A disclaimer must be acknowledged before first use.

Scan — target discovery

Profile — target analysis

Attack — broadcast and testing tools

Capture — review and export

Ghost Mode is the headline entry — it rotates MAC, kills radios, and cleans up state in one action (replacing the old standalone MAC Changer and RF Silence apps).

A single tile that merges the old Network section with crypto, productivity, tracking, and creative apps.

Security & crypto

Network

Productivity

Tracking & logging

Creative

Casino (slots, blackjack, roulette, coin flip, higher/lower, loot box), Minesweeper, Sudoku, Chess (with bot), Snake, Tetris, Maze, Dice Roller, Game of Life, Voronoi, Matrix Rain.

Full EPUB 2/3 rendering, KOReader Sync, and Calibre wireless transfer are inherited from CrossPoint.

Promoted to a top-level tile from the old System section.

Three UI themes, selectable in Settings:

• Classic — original CrossPoint style
• Lyra — rounded elements, modern feel (default)
• Military — inverted headers, sharp corners, dashed separators, uppercase labels

/biscuit/
  portals/        # HTML templates for captive portal
  ducky/          # DuckyScript files for HID keyboard
  pcap/           # Packet captures
  scans/          # Network scan results
  logs/           # WiFi/BLE scan logs, AP history, event logs
  drawings/       # Etch-A-Sketch saved BMPs
  trails/         # Breadcrumb trail data
  snapshots/      # Network change snapshots
  flashcards/     # Flashcard decks (CSV)
  creds.csv       # Captured portal credentials
  medical.dat     # Medical card info
  totp.dat        # TOTP authenticator secrets (encrypted)
  casino.dat      # Casino credits
  habits.dat      # Habit tracker data
  security.dat    # PIN hashes
  automation.dat  # Automation rules
  oui.txt         # IEEE OUI vendor database (user-provided)

1. Connect your Xteink X4 via USB-C data cable (not charge-only)
2. Wake the device by pressing Power
3. Go to https://xteink.dve.al/ and flash the firmware

To revert to stock firmware, use the same site or press "Swap boot partition" at https://xteink.dve.al/debug.

git clone --recursive https://github.com/yattsu/biscuit
cd biscuit
pio run --target upload

• PlatformIO Core or VS Code + PlatformIO IDE
• Python 3.8+
• USB-C data cable
• Xteink X4

# Windows PowerShell
$env:PYTHONUTF8=1
pio run -j 16

# Linux / macOS
pio run -j 16

Translations live in lib/I18n/translations/. Each language is a YAML file. Add or edit strings, then regenerate:

python3 scripts/gen_i18n.py lib/I18n/translations lib/I18n/

See i18n docs for details.

python3 -m pip install pyserial colorama matplotlib
python3 scripts/debugging_monitor.py

The debug monitor shows color-coded logs and a real-time memory graph.

The firmware uses an activity-based UI architecture. Every screen is an Activity subclass with onEnter(), loop(), render(), and onExit(). Activities are managed by ActivityManager (push/pop/replace). WiFi and BLE share one radio, arbitrated by RadioManager.

See architecture docs for the full overview.

Biscuit tracks CrossPoint Reader as upstream. To sync:

git remote add upstream https://github.com/crosspoint-reader/crosspoint-reader.git
git fetch upstream
git merge upstream/master

Built on CrossPoint Reader by the CrossPoint contributors. CrossPoint was inspired by diy-esp32-epub-reader by atomic14.

MIT