Replies to This Discussion

Permalink Reply by Scott VanFossen on June 19, 2012 at 2:34pm

Are you running it off another battery? Or directly from the main battery?

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Permalink Reply by Cody O. on June 19, 2012 at 8:57pm

I'm running everything from a single 7.2v battery.  Since I'm using a joystick, I don't have a receiver.  The ESC (w/ 6v BEC) powers all the servos through the APM2 output rail.  The lone BEC (5v) powers the APM2 through the input rail.

Permalink Reply by George on June 19, 2012 at 4:30pm

I agree Cody, having all the same problems as described here, I solved mine by using a LC filter on the supply to the input rail. So simple yet weeks of frustration.

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Permalink Reply by Jonathan M on June 19, 2012 at 8:03pm

I guess my problem is a bit different:  get sats but no 3dfix no matter how long I wait. 

Tried using my CC BEC on the output rail with no difference.  Still stumped :(  Think it may just be a hardware issue

Permalink Reply by Cody O. on June 19, 2012 at 8:59pm

George: Cool idea.  I've seen a lot of BECs come with chokes on the output lead.

Johnathan: Does it get a fix when is connected to just the USB?  Try removing the jumper from JP1 and powering the board through the input rail with your BEC.  Also, if you have other electronics on-board, try letting the GPS get a fix before you turn everything else on.

Permalink Reply by Jonathan M on June 19, 2012 at 9:34pm

Nope, nothing gets me a fix any more.  The strange thing is that I used to have no issue getting a fix.  Hence, why I think that the GPS is damaged somehow.   Just don't know how, especially since it's still see Sats.

My receiver is powered directly via the lipo.  So, nothing is drawing it's power from the APM currenlty

Permalink Reply by Cody O. on June 20, 2012 at 4:24am

Maybe if you could describe your setup and the steps you've taken to troubleshoot, it could give some idea of what's wrong.  Right now it sounds like bad power or some other interference.

Permalink Reply by Jonathan M on June 20, 2012 at 2:07pm

http://diydrones.com/forum/topics/apm-2-gps-not-getting-a-lock?xg_s...

You can see my discussion about this above.  Basically, I get a consistent blinking 3dfix, but never solid blue.  When connected via USB, same story but the MP reads sats and an hdop = 9999.

When running off of battery I have tried using a BEC at 5.1v to power the APM seperately.  No luck

As I mentioned, for about 4 months, I never had this problem.  No major changes to hardware that I can think of to cause this problem either.

Permalink Reply by Cody O. on June 20, 2012 at 4:10pm

"I was getting 5-7 sats consistently, but there was no lock.  9999hdp as well"

"I really am out of ideas. 1.5+ hrs of 6-7 sats with no 3Dfix."

Jonathan,

It could be your environment.  At my office I get 10-11 satellites, but the location dances wildly up to 100m.  My best guess is that all the nearby sheet metal covered buildings are playing havoc on the GPS signal.  At my rural testing grounds it's another story; I get a fix good enough to track a 1m width walking path.  Try taking your bare APM2 to a different location and see if you get a lock then.

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Permalink Reply by Jonathan M on June 20, 2012 at 6:03pm

Hmm.. could be, but then again, I would get lock no problem in the same environment prior to this issue.  I will try in an open area when I get a chance. Thanks for the tips

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Permalink Reply by Dr Mike Black on July 5, 2012 at 3:25am

Hi all,

Got a similar problem MTK does what it wants to do, and have tried all power configurations, with varying degrees of failure. (It will lock up sometimes.....sometimes!)

With the APM2  built in MTK , which is giving me nothing but problems, so want to shift the GPS to another port at 38400, having trouble getting the APM to switch GPS onto another UART to make the nightmare MTK redundant and use a known good GPS...(ublox)

It would be helpful if any of the community has/is/or trying to do exactly this, some input would be really great!

(complete noob on APM2 (many year exp on AP/APM1), only just got it up and running however, i have had problem after problem with the MTK units, either on their own, or in other applications over the last few years, IMHO they are too easy to blank/upset/annoy...never really experienced belligerence and or petulance in an inanimate object before : )  Perhaps dinner and flowers might be required to get them to put out for us!?   )

Personally, i have no issue if a unit is screwey, but it must be realiably screwey. so you can create a work-around...not what seams to be a completely random set of behaviours, based upon, whether you have black or grey underware on, which type of car is parked outside no.30 on a wednesday morning, and if planet X is having a solar eclipse..

MTK units have given me issues on AP (all 6 we have flying) APM1 (2 off) Remzibi OSD (3 off) drops out all the time, loses home....

I am wondering if the unit itself, has enviromental requirements, that MUST be met, but only work fro a portion of this community, location depending.

Either way i have 8 of these suckers....and not one, behaves in a predictable fashion, in relation to itself and the others.

Ublox.....every time....on the nail! No questions...no mucking about....

Another issue here in the UK is that there are no WAAS or similar so we cant grab extra data from other sources..

Anyway looking forward to anyones thoughts on tthis issue.

Kind regards,

Mike.

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Permalink Reply by Cody O. on July 31, 2012 at 2:36pm

There's guide floating around somewhere on this site that shows you how to disable the onboard MTK GPS.  I *think* you solder-jumper pins 2 and 3 on the GPS to disable it, then just connect the external GPS and you're ready to go.

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