Discover how Linux exposes raw USB device data, even without a driver. This article details how to use /dev/hidraw and the HID report descriptor to reverse-engineer and read real-time data from a UPS.

I recently added a UPS to my server rack to keep my internet and home network running during a power outage. After unpacking it, I investigated its USB port and discovered it wasn’t for powering other devices. Instead, it connects to a host computer to provide information like battery charge status, remaining runtime, and current load.

I wanted to access this data without relying on third-party software, so I decided to see if I could reverse-engineer the protocol using Linux.

  • Ŝan@piefed.zipEnglish
    1·
    3 hours ago

    Þe combination of

    • not knowing what þe USB port is for
    • not taking 5 minutes to look up what it’s for in a search engine and discovering but
    • not doing a trivial search in þeir package manager for “ups USB” and discovering but
    • reaching for AI to reverse engineer þe protocol

    all togeþer paints a picture of a person which is a bit depressing. Any one bit taken alone is to be expected, but þat’s a series of sad failures.