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Hi Larry,

start with enable debug messages from the ardupilot ublox driver https://github.com/diydrones/ardupilot/blob/master/libraries/AP_GPS... .

Best regards

Mirko

Thanks Thomas.  Before connecting, I verified (or at least I thought I verified) that the GPS compass serial outputs were already at 3.3V.  I couldn't find a schematic of my unit, but assumed it has a regulator in there to step the 5 volts down to 3.3. Maybe I better go back and check those voltages...

Also, I have a sneaking suspicion that the GPS compass is finicky about its power supply.  That has been a key difference in how I've been testing at home.  When I switch over to the APM, the GPS compass is powered off of the USB port on the APM, but on the BBB it gets its power off the 5V power supply from the wall.  However, I just switched the BBB over to battery power, and the GPS still isn't working.  Power supply is at 5.2 volts, which should be good enough for the GPS. 

Great suggestion.  So I understand I want to set:  #define UBLOX_DEBUGGING 1

Dumb question...  it looks like the debugging code is sending the output via a "hal.console->printf".  Where does that send the text?  To the command line?  I have the code autostarting at BBB boot-up, so will probably need to kill it and restart.

Also, my compass is giving me headaches now.  EKF is complaining "Error Compass Variance" and "Bad AHRS", and heading is drifting all over the place.  It was working!  Still works when I plug in the APM, so something about this darned BBB setup is not liking my GPS or compass.  Maybe I need to try a different GPS/compass.

Nevermind about the compass problem!  I had forgotten to reconnect the I2C port, so it was grabbing the compass measurement from the MPU9250.  I haven't calibrated that yet.

That GPS, on the other hand, is still a problem...

I finally got my GPS working. It turned out to be a power supply issue, nothing to do with BBB. I can't say why this fix works, but I noticed that when the BBB is powered off of my 5v wall power supply or Lipo battery, the GPS did not work, while powered off of the USB power, it does. My wall supply isn't very precise and outputs 5.25V. My battery goes through an APM power module (from Hobbyking) and provides 5.5v, which gets knocked down to 5.2 after the Schottky diode I put in series. The USB puts out 5.0v. So I put together my own L7805cv voltage regulator to independently power the GPS, and viola, it works! The regulator outputs a steady 5.0v. I've checked several times to verify the problem reappears when power it the old way.

I can't understand why this would make any difference. I have a cheap GPS compass unit so am not surprised it isn't robust. The receiver is a NEO M8M powered by a 3.3v regulator inside the unit, so shouldn't care if the externally applied voltage is 5.0 or 5.2v. But it does. Anyway, as long as the BBB is working, I'm happy.

So my BBBMINI quadcopter is now all ready to fly... Wish me luck!

Great to hear that Larry!

It somehow sounds like my Neo7 GPS that does not want to play with one of my BBBmini's.

I will try to see if it is a similar thing again now :)

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