Dean Hall needed an
inexpensive GPS module that could interface with a
microcontroller for use on his outdoor robot project, named Argonaut. He started by
comparing the two least expensive USB GPS modules, the Holux
GR-213 and the EverMore
GM-R900, both of which use the SiRFstarIII chip.
Indoor reception, outdoor reception, and other details were compared
before selecting the GM-R900. Dean then offers photos
details of the GM-R900, revealing that the board itself
has a serial connection which goes through a serial to USB adapter in
contained in the cable. The serial interface uses standard NMEA protocol
and should be easy to connect to virtually any microcontroller. Dean has
written some Python code to communicate with the GM-R900.