These units have recently come on sale on eBay for £15 or less and consist of a Ublox NEO GPS and a HMC5883L compass chip. These purple pcb units are designed to attach to a APM 2.6 flight controller for quad copters etc. I purchased one recently from China and found there was little or no information about them. Probably the best information was on the first result on Google which had a labeled picture.
I found there seemed to be at least two variations, one had the connectors on either side of the board and was fitted with a Ublox NEO 4 GPS unit. The other had the two connectors side by side and was fitted with a Ublox NEO 6 GPS unit. Some had the Ceramic Active Aerial soldered to the board, others (the type with connectors either side of the board) had the Connector for the Active Aerial passed through a hole with a connector attaching it to the board.
My unit seemed a hybrid of the two, it has the connectors either side of the board, a hole for the aerial lead, but the Active Antenna is soldered to the board. The GPS unit, however, is a Ublox NEO 6.
The connections for the unit seem to be the same, the HM5883L is connected to a four pin female connector, this has Gnd, +ve, SDA and SCL connections. The GPS has a six pin female connector, 2 Gnd connections, +ve, Tx and Rx connections, one pin is unused. From my experience with the Ublox 6, the power supply should be 3.3 volts and the signal pins should be connected to a Logic Level Convertor, if it is to be used at 5 volts on an Arduino.
This connection diagram shows the connections for the unit with the connectors side by side.
The pin connections are shown for the version with the connectors either side of the board at the top of this post. I intend to start testing this board out over the next few days, once I have cut the plugs off the end of the connectors and soldered 0.1 in pitch pins to them.