APM 2 GPS not getting a lock?

I have been sitting here trying to get a lock with my GPS while outside for about 10 mins.  No luck.  I generally get a lock between 30-60s when outside.  My GPS has worked fine previously.

Other than the CLI test (which only works if I have lock anyway), is there a way to check GPS function?

If my GPS unit turns out to be no longer functioning, what options do I have with the APM2?  Since my GPS is soldered directly to the board, is it possible to get another and use an extension?  I don't trust my soldering abilities enough to remove and replace the current unit

Thanks

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Replies to This Discussion

Permalink Reply by Michael Müller on July 5, 2012 at 2:02pm

Has anybody tested it with an older firmware than 2.6? Maybe it´s a software issue.

Permalink Reply by Owen Booth on July 7, 2012 at 12:35am

Yep, I'm the same. 2.6 FW, no lock when self-powered, but full lock fairly quickly when fed by USB. What the??????

I see Andreas posted:

"Comment 9 by  project member  andreas@antonopoulos.com, Jun 4, 2012

Problem indicated solved. Not software related "
But I've no idea how to find this resolution. Anyone?
Permalink Reply by Daniel Portillo on July 10, 2012 at 12:46pm

I have the same problem, I have two APM2 and one APM1 all with mediatek GPS, and powered with CES.

  • APM1 work fine.
  • A APM2 didn't lock GPS  (30min) and I thought this was because the power wires and canopy block the signal, therefore I cut a path of integrated GPS for canceled it, and I conect a external gps. With this, all worked fine.
  • The other APM2, I have installed in a clear place in the plane and the gps no lock (30 min).


I'm going to try power by the USB.

I think this is a serious issue, because our boards are garbage if don't lock the GPS.

Permalink Reply by Owen Booth on July 10, 2012 at 1:13pm

Mine did work fine with the 2.5 FW, only 2.6 that I have issues with. Anyone from 3DR want to pipe up and give us some guidance?

Permalink Reply by Owen Booth on July 11, 2012 at 1:47am

Oooh, just did a quick test

Interesting results. If I power from the ESC BEC I get 4.93v going into the APM, and just 4.63v feeding the GPS module, and no lock.

But if I feed it directly with a ni-cad pack of 6xAA's, I get 5.2 v into the APM, and 4.84v at the GPS module and a rapid lock (sub 2 mins)

 

So a dedicated BEC might be the answer?

Permalink Reply by Michael Müller on July 11, 2012 at 2:40am

Have you powered the rest of your onboard equipment with the Lipo, while testing with the ni-cad pack? Otherwise you have no possible interferences with ESCs or other and this is the raeson for the quick lock.

Permalink Reply by Owen Booth on July 11, 2012 at 3:37am

Yep, ran APM on the NiCad pack, and powered up ESC's etc with Lipo, and still got a lock.

Ordered a separate 5V BEC (turnigy), so I'll keep you posted ;)

Permalink Reply by Michael Müller on July 11, 2012 at 3:51am

I use this 5V Turnigy UBEC. It outputs 5.22V. It is working great with APM ouside the copter. But when I put it in place and power up the ESCs -> most times no lock.

Permalink Reply by Daniel Portillo on July 11, 2012 at 4:11am

Do you want to say when you plug the UBEC to AMP2 input rail the GPS don't lock?

Permalink Reply by Michael Müller on July 11, 2012 at 4:48am

No.

No matter from which side (inpu or output rail) I power the APM, I get no lock, when I put the APM in its place in the middle of the copter. Outside the copter, the APM laying on the table, GPS-Lock is ok.

But now I have installed a backup battery on the GPS and lock time is ok now. But GPS accuracy is quite poor. I discribed it here.

Permalink Reply by Daniel Portillo on July 11, 2012 at 3:36am

I read this in the manual:

"Alternative ways to power your board

The board comes from the factory setup up to be powered by your RC system, with RC input and output power shared. On the bench, you'll probably be powering the board via your USB cable while you set it up and test it. But in your aircraft, you'll need to power it with your onboard power system, which is usually your LiPo battery going through an ESC.

It's also possible to power APM 2 from two seperate sources, one powering the RC system on the input side, and the other powering the output side (servos or ESCs). This is determined by a jumper on the JP1 pins (see below). If the jumper is on, which is the factory default, the board is powered from the Output rail. If the jumper is off, the board is powered from the Input rail, but the Output rail will need its own power source. This configuration is used if you want to have two seperate power sources in your aircraft, one powering the servos and the other powering the electronics.

The APM2 is designed to properly operate from a clean, well filtered power source. Be aware that the voltage specifications are different depending on which connectors are used. The reason for this is there is a schottky diode (diode D1) that prevents the USB port, when connected, from sending power to the APM2's PWM Output connector and damaging something. Consequently, when the USB is not powered and power is connected via the PWM Output connecter there is small voltage drop across this diode in normal operation and a higher input voltage is required to compensate. Therefore, power requirements are as follows: 5.0VDC +/- 0.5V supplied into the PWM input connector, jumper JP-1 removed. 5.37VDC +/- 0.5v supplied into the PWM output connector, jumper JP-1 in place"


I think that the issue can coming from drop of voltage diode D1. I'm going to try connect in parallel a ubec (5A and 5V http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=...) with the esc ubec (2A and 5V http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=...) for more constant voltage.
I'd like can connect the APM2 to a separate battery with ubec, but like I have instaled all wires  in the airframe, I can't acces to wires to modify it.

 

Permalink Reply by Owen Booth on July 11, 2012 at 3:41am

LOL, "if in doubt, read the manual" ;)

I'll be sure to post once my new 5v BEC is installed, see if having full 5V helps.

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