MRo Location One compass not working after upgrade

Hi All,

I have a two* MRo Location One units where the compass has stopped working after upgrading the firmware. They were previously on AP_Periph-1.2 and were upgraded to 1.4 then to 1.5. I am attempting to downgrade the units, but I have not been able to find an old ap_periph download and I have not been able to compile that version yet either.

Is there anyone else with a Location One on the latest version of AP_Periph? Does anyone have any suggestions for locating or compiling the old version of ap_periph to verify the issue is firmware related?

Example compass data from second unit:

Debug information from the second unit:

Node properties from second unit:

*These units were “new old stock”. The first unit I never confirmed the compass worked before upgrading. However I did confirm the compass was operating before updating the second unit.

@pkocmoud Do you have a download for the production version of the Location One firmware?

I believe I have confirmed the issue is firmware related. I was able to compile AP_Periph-1.2 and downgrade the unit. The compass is now functional again.

Node properties from second unit after downgrade:

Compass data from second unit after downgrade:

For reference:

AP_Periph M10070 v1.2.e6c71b56 with working compass (Compiled locally)
AP_Periph-M10070-v1.2.bin (155.0 KB)

AP_Periph M10070 v1.4.f183785c with not functioning compass (Downloaded from build server)
AP_Periph-M10070-v1.4.bin (163.3 KB)

Hi DroneWrangler,

Sorry for the late reply. I just tested what you posted and both firmwares are working fine, no issues with mRo Location One. Most likely RM3100 sensor is damaged and the readings don’t pass the AP_Periph checks on the newer versions.
I downloaded both files from, verified the readings using DroneCAN GUI Tool and did a compass calibration successfully using a mRo Pix Racer Pro.
Try to look for mechanical damage on your unit, perhaps one of the coils is broken.

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