{
  "added_at": "2026-11-09",
  "additional_evidence_urls": [
    "https://github.com/iliasam/Laser_tape_reverse_engineering/blob/fd829618ed7075ca104cbe742e6d5be4f7f31813/PC_utility/Readme.md"
  ],
  "category": "reconstruction-cases",
  "class": "hardware",
  "description_en": "The X-40 laser rangefinder study reconstructs the tape measure's circuit and replaces its firmware for DIY distance measurement. The author captured I2C packets with a logic analyzer, decoded modulation-frequency values and wrote firmware that processes signals with a Goertzel algorithm; PC utilities display captured data and results.",
  "description_zh": "X-40 激光测距研究重建了卷尺电路，并编写替代固件用于自行测距。作者使用逻辑分析仪抓取 I2C 数据包、解读激光调制频率值，并编写采用 Goertzel 算法处理信号的固件；PC 工具可显示采样数据和测量结果。",
  "entry_url": "https://awesomerea.org/resources/x40-laser-rangefinder-case/",
  "entry_url_zh": "https://awesomerea.org/zh/resources/x40-laser-rangefinder-case/",
  "evidence_url": "https://github.com/iliasam/Laser_tape_reverse_engineering/blob/fd829618ed7075ca104cbe742e6d5be4f7f31813/README.md",
  "group": "cases",
  "id": "x40-laser-rangefinder-case",
  "json_url": "https://awesomerea.org/resources/x40-laser-rangefinder-case/record.json",
  "kind": "case-study",
  "markdown_url": "https://awesomerea.org/resources/x40-laser-rangefinder-case/index.md",
  "markdown_url_zh": "https://awesomerea.org/zh/resources/x40-laser-rangefinder-case/index.md",
  "name": "X-40 laser rangefinder: circuit and firmware reconstruction",
  "name_zh": "X-40 激光测距模块：电路与固件重建",
  "record_type": "resource",
  "relationship": "independent-reconstruction",
  "requirement_facets": [
    "prerequisites",
    "prerequisites",
    "testing",
    "license"
  ],
  "requirements": [
    "Requires a supported X-40 module; the README lists 512A, 701A, U85A/U85B and B2A families, while M88B is unsupported.",
    "The fast distance firmware requires zero-distance calibration on first start.",
    "The author reports accuracy varying from 1 to 10 mm with distance and surface type.",
    "MIT License."
  ],
  "requirements_zh": [
    "需要受支持的 X-40 模块；文档列出 512A、701A、U85A/U85B 和 B2A 系列，M88B 不受支持。",
    "快速测距固件首次启动时需要进行零距离校准。",
    "作者报告精度随距离和表面类型变化，范围为 1 至 10 毫米。",
    "MIT 许可证。"
  ],
  "targets": [
    "firmware",
    "protocol"
  ],
  "url": "https://github.com/iliasam/Laser_tape_reverse_engineering",
  "verification": "source-reviewed",
  "verified_at": "2026-11-08"
}