Current setup:

APM2.5 w/ ArduCopter V2.7.3 Quad

3DR GPS uBlox LEA-6 w/ stock configuration from the diydrones store


Power via USB only

On the GPS board, the red power light is on constant and the blue fix flight is flashing.  So no GPS fix right?


but the AMP2.5 has a solid blue light indicating GPS fix and when connected to the mission planner via USB, I see that I have a 3D fix with 12 satellites and gpstatus=3.  Also it appears that the location is within a reasonable range of where I actually am.

When the quad is powered via the 4.7V coming off of the esc bec's I still get the flashing blue fix light on the GPS.

So do I really have a GPS fix or what is going on.

Should the light on the 3DR GPS uBlox LEA-6 go to solid blue?

Any insight would be appreciated,


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I think that may be the distinction in the quality of the fix, with the APM LED accepting a lower quality fix (number of sats, etc). At any rate, as long as you're seeing 3D Fix in the MP, you should be good to go. 

12 satellites not enough for a fix?  Who knows what the GPS is thinking

I was looking into updating the firmware on the Ublox LEA6H, but I wasn't sure what version to use.  There are four options,   Which one am I looking for?


I am getting the same thing as you, so not yet comfortable to try auto flights...just wrote a question on this as well before seeing this one. Let me know if anything change son your side.

I've used loiter mode and it appears that the GPS does have a lock.  I haven't been brave enough to do an auto flight either, but maybe this weekend!

Hello totgether,


I'm getting in trouble with the original connector on the 3DR GPS uBlox LEA-6, on the back side there are 4 copperpoints where i can connect Power + Gnd also the Tx and Rx signal. the question that i have is the following, can someone support me on the Ardupilot 2.5 to figure out which pin (out of the 8 i think) must be connected to the GPS Module (without using the original connector on the GPS Module).


many thank in advance


Yep, I think must be wrong description in the Wiki saying that it must be fixed blue led in the gps unit as a flew a bit yesterday in Loiter as well and it seems to hold however I don't think I have all the right PIDs set yet since sometimes it starts to drift away to one side and does not seem to come back without my input on the stick. It could be the wind as well.

I will try auto when I get a chance to get to a wider flight area and do only 2 points to start...

Hi all,

I think that I have solved the mystery of the flashing blue LED on the uBlox pwb that says "fix". After reviewing the GPS schematic, I found that the "fix" LED is hooked to the "TIMEPLUSE" output of the uBlox chip. The literature states that it is programmable from .25 Hz to 1kHz. I would assume that once the GPS has acquired sufficient satellites and has a time lock, it will pulse the "TIMPLUSE" line causing the "fix" LED to blink at whatever rate it has been programmed. Therefore, the "fix" LED is an indication of GPS lock and will probably flash as long as there are sufficient (how many?) satellites for a lock, but will never go solid.



Thank you very much!  Hopefully this will get documented somewhere

Thomas, you are correct. The blue LED will blink at 1Hz when the GPS has a 3D fix, and will stay off during acquisition / cold start.


Just a guess, but the confusion may be that on the APM 2.0, the GPS lock is indicated by a solid blue LED on the GPS board.

Yes, it actually depends on the how each chipset indicates a fix. The Mediatek will blink when acquiring and stay solid when fixed, the uBlox will stay off while acquiring and blink when fixed. The APM itself will always blink the blue LED when acquiring and stay solid when fixed, regardless of which GPS is connected. I believe the APM's behavior was carried over from when the Mediatek was the more widely used GPS so they decided to replicate the MTK's LED behavior. The previous uBlox that 3DR sold (LEA-5 with a helical antenna) didn't have any LEDs, so there was no confusion.


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