CC Usage Elink

cc-usage-elink

Display your Claude Code usage on a BLE tri-color e-ink screen — always visible, zero screen time.

Hardware

Required: 蓝签 (LANCOS) 4.2-inch tri-color e-ink display, model EDP-42000DDF

- Resolution: 400 × 300 px, tri-color (black / white / red)
- Interface: Bluetooth BLE
- Protocol: 蓝牙BLE通讯协议 V2.1 (LANCOS proprietary)
This tool uses the LANCOS BLE V2.1 protocol. It is only compatible with the
蓝签 EDP-42000DDF (and same-protocol variants). Other e-ink displays will not work.

Requirements

- macOS (Bluetooth + Keychain APIs used)
- Python 3.13+
- uv — dependencies install automatically on first run
- Claude Code OAuth token with user:profile + user:inference scopes

Quick Start

elink.py is a single-file script — no installation needed, just uv.

After setup:

Commands

OAuth Token

You need a Claude OAuth token with usage-reading scopes. Three ways to provide it:

Option 1 — Via claude CLI (recommended)

Option 2 — Manual paste

Option 3 — Keychain (auto-detected)

Token lookup priority: ~/.config/elink/config.json → Keychain usage-elink-oauth → Keychain Claude Code-credentials

Config File

Stored at ~/.config/elink/config.json:

BLE Protocol Notes

The LANCOS BLE V2.1 protocol sends full-screen image data in two passes (black channel + red channel). Key timings that prevent display artifacts:

- 3 s delay after start packet (device init)
- 1 s per packet for first 10 packets
- 0.6 s per packet thereafter
- Write Without Response only (response=False)

Total transfer time: ~100 seconds per full refresh.

Known Issues

License

MIT