External compass not detected?

I am setting up AC ver3.6.11 on a Pixhawk 2.4.8 FC. I have a GPS plus compass module connected, but when I have a look at the HW ID section of Mission Planner, only the internal compass (a LSM303D) is listed, as shown here:

My external compass is an AK8975 connected via I2C, which I understand is supported by ArduCopter.

I also notice that the HW ID list above does not mention the barometer that is within the Pixhawk FC?

Hmmm, this is interesting - I have another drone that I built (a hexacopter) that I have just noticed also does not recognise the external compass, according to Mission Planner.

In this case, the compass that is included with the M8N GPS module is supposed to be a HMC5983 chip, but when I open the clamshell housing for the GPS/compass, the compass chip is marked with A983. From what I could find on the internet, the A983 is a clone/copy of a HMC5983 …

How can I find a list of what compass chips are currently supported by ArduCopter?

With a bit more research and testing, I think I have answered my own queries.

I have a genuine HMC5883L on a little break-out board, so I connected it to the I2C bus and now it is recognised as an external compass:

I think that I also found a list of the currently supported magnetometer chips and they are:


It is interesting that the HMC5883 is not on that list, but I guess it is included in the HMC5843 group?

In which case, shouldn’t the AK8975 be included in the AK8963 supported group?