Curing GPS-Induced Random Mouse Movements

Especially during the testing, I've noticed that when I plug my GPS into the computer (via a USB to RS-232 adapter), that the cursor on my Windows 7 PC will randomly bounce around the screen, occasionally clicking on things. This of course is less-than-desireable, especially during a chase.

To reproduce this issue, the sequence of events is as follows:

  1. Plug the USB to RS-232 adapter into the computer and load the device drivers as normal.
  2. Verify the proper operation of the adapter.
  3. Unplug the adapter from the PC.
  4. Turn on the GPS.  I've experienced the problem when running 4800 baud NMEA strings.
  5. Plug the GPS into the adapter.
  6. Plug the adapter into the PC.

The key seems to be having lots of random data flowing in when the USB adapter is plugged into the PC.  If you have the GPS turned off when you insert the adapter, there is no problem.

Bruce Coates (VE5BNC) came up with a good solution, assuming that you don't ever run the old serial-style mice on the PC.  Basically, there is a hidden system service that handles all serial mice.  If you don't need this functionality, you can simply disable the service by using the Registry Editor.

  • Click on Start  - Run
  • Type 'regedit' and click OK.
  • Drill down to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SerMouse
  • On the right side of the window, double click on the value named Start.
  • Change the value from 3 to 4.
  • Click OK
  • Close Regedit
  • Reboot Windows