Case study

CH899: reconstructing the clock's MM32–ESP exchange

CH899 firmware research reconstructs the UART exchange between the clock's MM32 movement controller and ESP8285 Wi-Fi module. It records wake, time and reset messages from stock behavior and implements replacement ESP firmware that adds Wi-Fi setup and timekeeping options while retaining the original movement controller.

Targets: Firmware · Protocol
Category: Independent reconstruction cases
Relationship: Independent reconstruction project
Sources reviewed: 2026-11-06
Evidence class: C1 partial scope or analysis entry

Stars: 3
Last commit: 2026-10-24
Language: C++
License (GitHub): GPL-3.0

GitHub data as of 2026-11-10

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Evidence

Demo screenshot from the project's public documentation

Observed: Download and demo observed; the case covers part of the target software.
Scope: Partial
Checked: 2026-11-08

How evidence classes are assigned

Requirements & limits

Prerequisites: The older CH899 clock board whose main chip is marked MM32.
Scope: Replacement applies to the ESP8285 Wi-Fi firmware; the MM32 movement firmware remains in place.
License: GPL-3.0-or-later license.

Cite

BibTeX

@misc{chouchin-ch899-firmware-case,
  title = {{CH899: reconstructing the clock's MM32–ESP exchange}},
  howpublished = {\url{https://github.com/maddenste/Chouchin-CH899-Firmware}},
  url = {https://github.com/maddenste/Chouchin-CH899-Firmware},
  urldate = {2026-11-06},
  note = {Awesome REA entry: \url{https://awesomerea.org/resources/chouchin-ch899-firmware-case/}}
}

Plain text

CH899: reconstructing the clock's MM32–ESP exchange. https://github.com/maddenste/Chouchin-CH899-Firmware (accessed 2026-11-06). Awesome REA entry: https://awesomerea.org/resources/chouchin-ch899-firmware-case/

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About this entry

The description was reviewed against primary sources.

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Primary sources

docs/PROTOCOL.md GitHub · maddenste/Chouchin-CH899-Firmware · Revision aaf6492
README.md GitHub · maddenste/Chouchin-CH899-Firmware · Revision aaf6492
docs/REVERSE_ENGINEERING.md GitHub · maddenste/Chouchin-CH899-Firmware · Revision aaf6492