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.

  • frongt@lemmy.zip
    2·
    10 hours ago

    Actual serial, or that almost-serial that will shut down the UPS if you plug a serial cable in?

    • curbstickle@anarchist.nexusEnglish
      1·
      10 hours ago

      LOL actual serial

      I’ve replaced the battery in that sucker more than a few times

      Edit: its an old HP powerwise for the record, I think its 2 pins for serial, 6 for contact closure.