Using a GPS mouse as primary or backup GPS with the Brookhouse NMEA multiplexer.

It is now possible to plug a low-cost PS2 GPS mouse directly into the Brookhouse multiplexer as a primary or backup GPS. In combination with the automatic backup switching feature of the brookhouse mux, this is a great way of ensuring uninterrupted lat/lon fixes in case the primary GPS fails, at very affordable cost. Of course the GPS mouse can also be used as the primary GPS.

The PS2 connector is available as a low-cost option for all Brookhouse multiplexer models.

GPS mice are small, selfcontained GPS receivers incl. antenna, without any switches, buttons or display. They have a fixed cable, for output of GPS NMEA sentences. The same cable is used to supply power. GPS mice are designed primarily for use with a laptop, PDA or vehicle navigation system.

Common models are:

1. The GPS USB mouse.
2. The GPS PS2 mouse.
   
   

The same unit is often available with different connectors or with adapter cables. Adapter cables can sometimes be purchased separately.

The problem with all GPS mice in marine navigation systems is that they receive their power (5V) via the same cable as they output NMEA. It is therefore not possible to simply cut off the connector and insert the wires in the NMEA IN terminals of a multiplexer or other NMEA listener. It is also necessary to make a provision for the 5V power supply. This made the use of these wonderful small and affordable GPS units often impractical in integrated marine navigation systems.

The GPS USB mouse receives its power via the USB connector and can only be directly plugged into a (laptop) computer.

The GPS RS232 serial mouse comes with a 9-pin female D-sub connector. A standard 9-pin RS232 connector does not have a provision for power supply, therefore a second connector (USB) is often used for the power supply. As there are no longer many laptops with a 9-pin RS232 connector, GPS mice with 9-pin plug have become less common.

The GPS PS2 mouse is a serial GPS RS232 mouse, with a PS2 connector. The name GPS PS2 mouse may be confusing. It has nothing to do with PS2 mice or keyboards, it just happens to have the same connector, but with a different pin-out. A more correct name would be “mini-DIN” connector. (DIN= Deutsche Industrie Norm). Adapter cables are usually available to turn a GPS PS2 mouse into a GPS USB mouse or GPS serial mouse with 9-pin plug.

The Brookhouse NMEA multiplexer can now be supplied with a female PS2 (mini-Din) connector which allows the GPS PS2 mouse to be directly plugged in. The multiplexer supplies the 5V to power it via this connector. The GPS mouse is internally connected to NMEA input port 3 of the multiplexer. The user can decide if the GPS mouse will be used as a backup GPS, by activation of the automatic backup switching feature in the setup menu, or as the primary GPS. If a GPS mouse is plugged in, the external NMEA IN connector for port 3 should remain empty.

This provides a neat, clean and above all a very affordable GPS solution. The standard connector does not need to be cut off, no adapter cable is required, power supply is taken care of by the multiplexer. If a multiplexer with LCD is used, the lat/lon and other GPS data can be displayed, also if no computer is connected.