How to connect a HJ – GPS/Compass to APM 2.5?

Bought a “kit” that included a APM 2.5. And in the “kit”, also got a HJ – GPS/Compass in it.

It doesn’t have the usual 5 pin white micro GPS connector, but it does 4 loose wire/pin connectors.
The colors on the wires are red, white, blue, and black.

Can’t find docs how to connect this oddball GPS/Compass to the APM 2.5 .
Can anyone help ?

Thanks, Jack


After looking at the APM schematic for the GPS connection, you will need a five pin DF13 connector with some pigtails attached to it.
The connector is wired as follows:
The red wire is +5vdc
The next wire is TX out
The next wire is RX in
The next wire is NC
The last wire is RTN

Your GPS wires are probably
Red +5vdc
Black Rtn
Blue and White are TX and RX, but no way to tell. You have a 50% chance of hooking the TX and RX right the first time. If there is no GPS connection, but the red led is on, then reverse the TX and RX wires.

Thank you ! I understand your suggestion.

Guess my hesitation before starting to cut & splice wires is that this is marked as a GPS & Compass.

The suggestion may resolve the GPS connection… but what about the compass connection ?

Google says that this device supports I2C communication (of course no wiring diagrams).
Does APM support I2C - GPS & Compass connections?
(Just thinking out-loud.)

Surely I can’t be the first to connect this GPS/Compass to an APM ???

Thanks, Jack

Since your GPS module is really a GPS/Compass module with just a four wire connection, I suspect that it is strictly a I2C module which means that both the GPS and Compass communicate over the I2C bus.
I do not believe that the APM is setup for a I2C GPS, but you might research that angle to see if it can accept an I2C GPS.