A mouse started typing when its adapter’s 72-minute counter wrapped
Big Mess o’ Wires’ firmware account traces a strange mouse failure to a 32-bit microsecond timer. Rollover looked like a reset, and device state was left half-rebuilt.
After an hour or so, a mouse began typing keys. That is a memorable way for an adapter to ask for a firmware update.
In the Wombat maker’s account, a 32-bit microsecond timer wrapped and broke a time comparison. The firmware interpreted it as an ADB reset, cleared device state and failed to reinitialize everything properly.
The interval has a rather precise explanation^32 microseconds divided by 1,000,000 and then 60 is about 71.58 minutes. The maker reports symptoms after 30–60 minutes, so the reports are not a stopwatch measurement of the rollover itself.
The repair effort also used descriptors collected from about 200 USB devices to simulate compatibility tests. That let the developer exercise awkward device descriptions without purchasing every keyboard and mouse that supplied one.
The next boundary to test may be much smaller: the same write-up found a USB event queue that silently discarded arrivals after just four pending events.