Dynon needs your help: 5.4 GPS Nav Source Dropouts

dynonsupport

Dynon Technical Support
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If you have an EFIS-D10A, EFIS-D100, a FlightDEK-D180, a Dynon Autopilot, and a GPS (probably but not definitely a Garmin portable) that constantly drops from NAV and TRK mode to HDG mode, we want your help.

We're having difficulty reproducing the root cause of the issue here, and so the best way for us to see what you're seeing is to get data from your GPS device as the dropout occurs. If you're a bit technically-minded, here's what you need to do:

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What's necessary is to tap the TX wire from the GPS to the EFIS.
Bring the TX wire to pin 2 on a female D9, and bring signal ground out to pin5.

If you are using the programming port on your system as the GPS input, a Y-harness can be inserted between the GPS and the EFIS.

The D9 can then be connected to a serial port on a laptop and the data recorded. The laptop you use to upgrade your system will work fine.

A terminal program such as TeraTerm can be used to log the data; be sure to set it to the baud rate you use for your GPS.

Note the time you saw NAVSRC LOST and send us the data log and we'll do the rest.
 

dynonsupport

Dynon Technical Support
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We have an update on this issue, and a solution for you to try out:

To recap, some customers have been experiencing momentary GPS data dropouts from 3rd party GPS devices that can feed a D10/D100 series-based autopilot. When this happens, and the autopilot is following the GPS through either the NAV or TRK modes, the autopilot decides that the GPS has gone away. This, in turn causes the autopilot to revert to heading mode. Some customers experience this routinely, as often as every few minutes.

We've had a hard time characterizing the exact nature of the problem, and getting a smoking gun of the problem happening in action is pretty difficult for affected customers to do. So, while we aren't 100% sure that this attempted fix will work, we're fairly confident in it.

Below is a "beta" version of D10/D100 series firmware that is exactly the same as 5.4.3, except for that it includes an attempt to fix the above undesirable behavior. It has no new features, and it does not fix any other problems. This software is not considered an official release. Though it is considered stable, it has not received the full set of release testing that would normally be performed on a firmware release.

PLEASE tell us if this firmware fixes the dropout issue for you. We'd love to get both positive and negative confirmations from everyone that installs it. A post here or an email to support at dynonavionics dot com are the best ways to let us know how it works for you.


Download Link: D10/D100 series beta firmware
 

JR

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May 15, 2007
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Ran new software today, 3 hrs in flight, only a small margin improvement.
Previously I would see every 5 minutes a dropout now, it was approx 15 times over the trip
Did get a strange problem on shutdown where "hold to power down" text flashed and wouldnt shut down, moved fwd then backward a few screens - text still flickering - then held button and shut down as normal
 

dynonsupport

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Bummer, but thanks for the report! Anyone else have a chance to fly it?
 

redmark

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Aug 3, 2010
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I also update my RV-12's D180 and made a test flight this weekend. *Maybe* there was a small improvement it's hard for me to say. I typically found that I could fly for 20 min. then drops would start occurring... this weekend I was only up for 1.6 hr. with 3 drops.

-Ron
 

juhee

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Do SLSA DYNON systems driven by Garman GPS's have this problem?
 

dynonsupport

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If it has SkyView, as most Dynon-equipped S-LSAs are coming with these days, this is not a problem.

This issue affects some D10/D100-series units, when paired with some Garmin handhelds and the autopilot. Not all customers experience this issue, which is one reason it's been so hard to diagnose and fix it.
 

juhee

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Jan 22, 2012
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I've D100, AP74, Garman GDU375 w/updated system softward. I believe it is on par with a Garman 696 now. Is one of the Garman problem GPS the 696?

Are you at a stand still on issue resolution?

Thanks!
 

dynonsupport

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We think it is, though the data on which of the Garmin units are have issues isn't entirely clear. Does your 375-basd setup drop out when you have the AP on NAV mode following the Garmin's guidance?
 

juhee

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Jan 22, 2012
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Will verify and report. Thanks. Garmin 696 install manual indicates it and now the 375 with software upgrade are setting out the correct series of instructions.
 

juhee

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Jan 22, 2012
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Same, loses NAV Source several times in 30 min flight. This is pretty darn frustrating. Its seems as though it couples in NAV mode and wants to work but then goes lame searching 90 degrees either side of course. Even after being on course it will just start meandering around in all modes, including heading. Then there are times it works a few minutes. Or is it really working? Please explain what the roll servo slipping indication looks like and where. How can I tell if I have SV52s by looking on the screen. Is it possible slippage is the problem even with 52s? Maybe I need to arm variant and linkage hole. The airplane is a RANS S-19 ELSA.. Sorry for all the questions, I just searching for a clue.
 

rich1

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Feb 29, 2012
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I noticed even before I added the auto pilot software and servos on my 10A, my HSI page DATA (magenta via 396) would drop out for 1 second at times. So it been a problem before the auto pilot was installed.
 

Brantel

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Apr 2, 2007
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For the long term NAV source lost issue:

Let me be clear. I do not think the issue is with the Garmin GPS's or the Garmin NMEA data stream. I personally think the issue is in Dynon's code.

Reasons I think this:

•No other user of Garmin's NMEA data stream have reported an issue.
•People with other brands of GPS's have reported the same issue.
•I have spend hours and hours logging NMEA data from my Garmin GPS's and have never found an error in the data stream
 

Foxflier

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Dec 3, 2010
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After flying this weekend with the V6.1 696 update and finding my AP has returned to the normal lost source every half hr or so I started looking to capture the NMEA data.  I have a D100 and D120 and I use the Aux Serial receive line via the EMS as the serial input to the EFIS instead of using the EFIS serial input.

Has Dynon been looking at the potential for the dropout issue if the NMEA is being received by the EMS serial input? I've never tried using the EFIS serial in line to see if it makes any difference...
 

dynonsupport

Dynon Technical Support
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It doesn't make a difference, as far as we know, but we'd need some more field reports to be more sure of that.

Any of you experiencing the issue: What Garmin product, and what serial port is the GPS connected to?
 

TimJBennett

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Jul 25, 2009
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D100 D120 AP74 in RV7a. Used to have a Lowrance 2000C. Occasional loss of GPS data. Now with Garmin 696. Frequent loss of GPS data, Dynon changes magenta to yellow. Recently seemed worse flying South after having flown North. LIvermore to Auburn & back.
 

N436JR

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Sep 7, 2012
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My TruTrak ADI Pilot II does not drop Nav when connected to the Garmin unit from my Sep. 7th post .
 

dynonsupport

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An update here - we're going to be taking another crack at a fix for this issue. I'm not quite sure when we'll have a version posted. It's at least a few weeks away, but there will be more to come.
 
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