Hi, just read the wiki about external compass:
copter.ardupilot.com/wiki/common … rformance/
It says PX4 and Pixhawk is not compatible. And its due to the signal levels is 5v and those boards is 3.3V, although they are 5v tolerant it is not recommended.
The 3DR external board is based on hmc5883 and have a level converter.
There are newer chip available on ebay etc. which is HMC5983 and do not have the level converter and is therefore compatible with PX4/Pixhawk as stated in this thread:
diydrones.com/forum/topics/hmc59 … 2#comments
Maybe updating the wiki, that boards with HMC5983 is compatible with PX4/Pixhawk?
So some don’t have to buy a new GPS just to get the compass.
