On my APM2 when powering via LiPo, GPS-Lock is sometimes present after about 30 Minutes, and sometimes never.
I can get GPS-Lock (in about 2 Minutes) only when USB is connected. This is even working when connected via LiPo and USB together. I have tried many powering possibilities: UBEC in output with jumper set - BEC from ESC in output with JP1 set - UBEC in input and BEC in output with jumper on and off, nothing helped. Both blue LEDs are blinking.
I can´t use my APM anymore without GPS. It is only two weeks old, without any crash or something. On one day it is not working anymore.
Maybe my GPS is defective?
I am very grateful for any help.
Greetings from Germany
Just going on a limb here but the 433mhz 3DR radios had a problem with USB noise, so it's not entirely impossible that noise from your particular computer is blocking the GPS signal and that would go a long way in the explanation since this seems to occur anytime USB is plugged in. Try one of those ferrite beads on the USB cable or maybe a different machine?
First you should clear the memory and flash the firmware again. It could have become corrupted. If you have telemetry or any other optional sensors you should disconnect that until you get the GPS working correctly.
Thank you all very much for your suggestions. But last night I found what the problem is but without a solution.
The problem is a defective out1-Pin. As soon as I connect a S-cable from any ESC to pin 1, no GPS-Lock can be established. When I additionally connect the USB, I got GPS-Lock. This cenario is reproducable, I checked it a dozen times. Of course I reflashed firmware with prior erase. And of course I cut the red and black ESC-cables. Powering is via UBEC on the out rail with JP1 set.
Anything else works great, flys perfect stable, but no GPS when pin out1 is connected.
What options do I have now?
- send it back and get a new one ( it´s only two weeks old), than I´m maybe without a copter for weeks, I´m from Germany
- solder pin out1 new (do I loose warrenty than?)
- modify firmware to get the signals from pin1 to pin7 (I fly a hexa+) But than I can never fly a octo with this APM
Any other suggestions? What can I do now?
Are you absolutely sure that the problem is specific to pin 1? For example, do you get a GPS lock when your ESC BEC is connected to any other pin?
I think your problem sounds more like a noisy power supply (the BEC integrated in your ESC). I had a similar problem (as a few other people in the forum) and since I power the APM, GPS, etc. from a separate supply these have disappeared. Just an idea..
To prevent such problems I use this UBEC.
(see my next post)
This GPS-Lock-Problem drives me crazy.
Today I tested it again and placed the APM 4" outside the middle of the copter and now I get GPS-Lock even with out1 pin connected. I have nothing connected but power from UBEC on out-rail and the white cable from ESC 1. Placing it in the middle, over the power distribution board, Iget no GPS-Lock.
So I think Mike is right, it is an interfearence.
What con I do now? Can I shield it in any way?
I had exactly the same problem as yours : GPS lock when the APM 2 is USB powered and no lock when it is powered by the ESC. I had some results with an external ubec (the same as yours) + putting my receiver on one of my quad's arms + putting 1 ferrite coil on the cable powering my rx from the APM. It's still not optimal : sometimes I get a lock in 1 or 2 minutes, sometimes in 10 minutes and sometimes I don't get any lock. I ordered some thin coaxial cable and I will try to make every cable shielded + a shield below the APM with some coppered epoxy. I hope it will help...
If I knew the GPS is so sentitive I'd certainly ordered my APM with an external GPS...
In my case there were interferences with the power supply board directly under the APM. Maybe shielding with a CFK-Plate is also the solution for you.
And yes, a GPS which is not so sensitive would be great.
How thick is your CFK plate ? I'll try with a plain printed circuit board I already have first.
Thanks for your answer.
My CFK-Plate is 2 mm thick and on all 4 sides 2" larger than the APM. Maybe it also works with the circuit board. Good luck.
I placed a CFK-Plate between power distribution board and the APM. Now I Have GPS-Lock after 2-3 min.
Thank you very much for your help.