Case study

X-40 laser rangefinder: circuit and firmware reconstruction

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.

Targets: Firmware · Protocol
Category: Independent reconstruction cases
Relationship: Independent reconstruction project
Sources reviewed: 2026-11-08

Stars: 136
Last commit: 2025-07-22
Language: C
License (GitHub): MIT

GitHub data as of 2026-11-09

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Requirements & limits

Prerequisites: Requires a supported X-40 module; the README lists 512A, 701A, U85A/U85B and B2A families, while M88B is unsupported.
Prerequisites: The fast distance firmware requires zero-distance calibration on first start.
Testing evidence: The author reports accuracy varying from 1 to 10 mm with distance and surface type.
License: MIT License.

Cite

BibTeX

@misc{x40-laser-rangefinder-case,
  title = {{X-40 laser rangefinder: circuit and firmware reconstruction}},
  howpublished = {\url{https://github.com/iliasam/Laser_tape_reverse_engineering}},
  url = {https://github.com/iliasam/Laser_tape_reverse_engineering},
  urldate = {2026-11-08},
  note = {Awesome REA entry: \url{https://awesomerea.org/resources/x40-laser-rangefinder-case/}}
}

Plain text

X-40 laser rangefinder: circuit and firmware reconstruction. https://github.com/iliasam/Laser_tape_reverse_engineering (accessed 2026-11-08). Awesome REA entry: https://awesomerea.org/resources/x40-laser-rangefinder-case/

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About this entry

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Primary sources

README.md GitHub · iliasam/Laser_tape_reverse_engineering · Revision fd82961
PC_utility/Readme.md GitHub · iliasam/Laser_tape_reverse_engineering · Revision fd82961