User Manual

Input: Radio/OSD
The Radio/Minim OSD port follows the same pin-out as the GPS
Gnd Vcc Rx Tx
(Black, Red, Green, Yellow),
The supplied plug will go in the right way.
ie: TX goes to TX on the GPS, or Radio
This is labelled for the device you are using
Input: Compass
Gnd
Vcc (3.3v)
SCL
SDA
HK Compass
Make sure you cut the track between the two pads above the RESET label if using external compass
Warning: the SDA-trace for the external compass is extremely close to the pads, and also very easy to cut.
(Thanks Lars)
APM 2.5 Page 3