No fix for UBlox6 GPS on Revo
« on: April 13, 2016, 11:15:21 pm »
Hi Guys!
I've got this strange looking issue. I have Revo (fw: next 20160314) with uBlox Neo6 (pretty standard) connected to Revo via Main Port. I can see up to 11 satellites, have a time and location read but can't get a fix. What is really strange, occasionally (once every 10-15 sec) I get 3D fix for about 1 sec and then it's gone again.

This is what I did:
1. First, I reconfigured uBlox according to this manual "How to configure a GPS for CC3D" - http://opwiki.readthedocs.org/en/latest/user_manual/cc3d/gps.html
At this point the GPS can read up to 10-11 satelites in UBX data format
2. I connected the GPS to my Revo using "GPS setup" manual (Main Port/GPS/57600/UBX)- https://librepilot.atlassian.net/wiki/display/LPDOC/GPS+setup
I checked electrical connections (GND, VCC) and Tx/Rx - works okay, I have a time and location reading in GCS (see the screenshot)

Now I have no idea where to start to locate the rootcause. GCS works okay, firmware works okay, and... GPS technically works too. Any ideas or maybe somebody found the same issue before? Appreciate any help:)

F

hwh

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Re: No fix for UBlox6 GPS on Revo
« Reply #1 on: April 13, 2016, 11:31:51 pm »
...I have Revo... I reconfigured uBlox according to this manual "How to configure a GPS for CC3D" -

Why did you configure the gps for a cc3d if you have a revo?

Go into the ublox software again and reset it to defaults.   In gcs hardware tab set the port to GPS/57600/UBX and save.  Power cycle the revo and the revo's autoconfig should configure the gps the way the revo wants it.

f5soh

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Re: No fix for UBlox6 GPS on Revo
« Reply #2 on: April 13, 2016, 11:40:23 pm »
Like Hank says, Revo board do not need manual config, this only applies to GPS connected to a CC3D.
According to your uav file, looks like your Revo try to find the GPS baudrate in cyclic way.

Try reverting GPS settings to default / factory settings



Be sure the external power/voltage is ok
You can monitor the autoconfig status:
https://librepilot.atlassian.net/wiki/display/LPDOC/GPS+setup#GPSsetup-Troubleshooting


Re: No fix for UBlox6 GPS on Revo
« Reply #3 on: April 14, 2016, 03:10:18 pm »
@hwh yes, I probably underestimated my Revo in terms of data protocols handling:) But thanks for your comment.
@f5soh you and Hank were right about the rootcause - the Autoconfig looks very unstable.

I followed your comments and reverted the GPS settings to def config. Then in GCS I setup everything according to the manual and... my GPS couldn't fix (the same behaviour). The quick-fix (temporary) was to change the UbxAutoconfig value to disable and adjust the baudrate to make the GPS work. So problem solved for the moment. But I still suspect two possible causes:
1. Hardware issue - this uBlox may be defective, but I don't have another GPS now to confirm this theory. I should have a brand new uBlox 8 in coming days. Further test required.
2. Software issue - this is a custom build (next), and maybe in very specific circumstances the board can't auto configure and try to find the GPS baudrate in cyclic way. This is beyond my skills to debug and try to confirm this theory:/

Now I feel more confident to trace possible rooctauses similar to this one. I will reopen the case if I find that even with a second GPS the flicking don't stop. Thanks again for your help!
F

f5soh

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Re: No fix for UBlox6 GPS on Revo
« Reply #4 on: April 14, 2016, 03:43:02 pm »
If after reset to factory settings (9600bauds) and next connected to Revo the GPS is running at 57600bauds the autoconfig works.
With the UBXAutoConfig you can keep the autoconfig and remove the AutoBaud part.

Re: No fix for UBlox6 GPS on Revo
« Reply #5 on: April 14, 2016, 07:54:42 pm »
@f5soh case closed:) I think I didn't reset the GPS properly. Now I have fully auto fix:)

f5soh

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Re: No fix for UBlox6 GPS on Revo
« Reply #6 on: April 14, 2016, 08:13:44 pm »
Nice  ;D