Wednesday, March 25, 2015

Serial GPS device detected as "crazy" Serial Mouse

Windows will detect a Serial GPS device attached to a Com Port as a Serial Mouse and cause some "crazy" behavior.  Typically it will continually move the mouse to the top right corner of the screen every 1 second (the update interval of the GPS unit)

My particular application is a GPS unit plugged into a Toughbook CF-31 Docking station.

To resolve the problem, we can simply tell Windows not to enumerate any "Plug and Play" devices on the serial port.... or what it thinks are plug and play devices.

Here is a link to Microsoft KB283063 article.  But in case it disappears from Microsoft's site or gets moved.  Here are the details.
  1. Start Registry Editor (regedit.exe). 
  2. Navigate to the registry entry: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\ACPI\PNP0501\Port#\Device Parameters
    • Note that there is one Port# value for each port.
  3. Right click and Add Value, and then add the following registry value:
    • Value Name: SkipEnumerations
    • Data Type: REG_DWORD 
    • Radix: Hexidecimal 
    • Value: 0 through FFFFFFFE
    • Note: a value of zero (0) disables the feature and device detection can resume. Each time that Plug and Play does an enumeration, it counts down one, and when it counts down to zero, it re-enumerates the hardware and then starts counting down again from the registry value. When you reboot the computer, Plug and Play starts the count again at the value that you typed.
  4. Quit Registry Editor.
  5. Reboot the Computer and test.

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