Using Navspark as the primary GPS for APM


Hi guys,

I bought this little (cheap) GPS module months ago from an indigogo project. I have since received my GPS and was having troubles interfacing it to my APM 2.5.2. I was simply trying to output the serial data into the APM, not porting APM to the skytraq chip.

Here is where I posted my question, The guys here are very helpful with the info I needed.

It seems that all I needed to do was connect the TXD1 pin (navspark) to the RX pin on the GPS socket (APM) GND to GND and Battery (in) to the 5v output from the GPS socket. Then change the output of the Navspark to 5hz.

I don't know if there is any benefit to running a Navspark over a Ublox, or weather the APM is geared to accept the Beidou sat signals. 

If I have provided any wrong information or if you could provide further info, please let me know in comments below.


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  • Does anyone have or know of the whereabouts of an interface/adapter mentioned by Chris,above, for the Ublox Lea-5h GPS?

    I have been looking to buy one, new or used, for a long while without any luck, hence this cry into the wild.


    Joe Homer
  • when the GLONASS function is enabled.

    And that is the point. Thomas your great results with the LEA-6H are well known, but in our place in Central Europe, results comparining GPS only LEA 6H (3DR V1.1,V1.2) with  NEO M8N and even Max M8Q using GLONASS and GPS, are very well reflected by Peter, who published his results @ drones-discuss. Right now,the CSG with the big 35mm patch is my reference, I won´t go for less @ my setups anymore (except for trial purposes.) According to VR, Roberto, his NEO8 BOB is great as well, but I already had my CSG at that time.

  • Admin

    Hi All,

    I am using a 3DR GPS/compass module as my primary GPS and a uBlox M8Q as the secondary GPS and a review of the data logs indicates, when both GPSs are programmed with the latest 3DR configuration file, the M8Q is not much better than the LEA-6H. The M8Q is only much better when the GLONASS function is enabled.



  • I wonder if the 3DR auto configuration is only for those other receivers. All I thought it did was change the settings we have already set up. Baud, power, talker, etc.

  • @gervais: Interesting about only showing primary GPS, guess that should be logged as a bug and fixed - can't be a good idea to be seeing incorrect flight data when flying!

    My indicated (!!) HDOP is usually around 0.6-0.8.  What I meant is that when first booting everything up, when using the 3dr gps I usually wait until the HDOP is <2.50 (I often can't get below 2.0) and it seems to fly OK, whereas if I start flying with the Navspark above 2.0 it clearly isn't good enough for loiter - there's obvious movement.  I find below 1.8 is OK.  But I find the -GL gets a decent HDOP very quickly so I just wait until it gets down below 1.5 before flying.  Also I tend to run it off a dedicated battery rather than the telemetry port power as it doesn't have an onboard battery and thus loses lock every time you change the main battery.  A tiny 1s lipo will power the navspark for many hours and weighs less than 10g so I figure a good tradeoff, as it keeps lock for you all day and you can then change main batteries and get flying again very quickly.

    Off the top of my head the only thing I needed to set was the update rate to 5hz and the talker ID - everything else was A OK.  I think the baud rate is 57600? (I'm using pixhawk, if that matters).  the -GL only exposes tx on the primary UART so yes only connect that (and ground, if using battery).  The second UART exposes rx/tx on the pins so I imagine that could be used if apm/pixhawk wanted to update the GPS setup automatically.

  • @DOM, Well my indicated (!) HDOP @ MP (see the previous page) are well below 1.2 ;-) Never seen 1.8 so far. But that doesn´t help with the G2M1@PX

    Btw. one of your posts @ drones-discuss led me to buy the NavSpark GL as well. You just set airborne 4G, 5Hz Position update rate, 38.400 , GP NMEA talker, GLONASS and GPS,  and used just TXD1 (no Rx) ?

    Or what else did you change / compile ?

    PS: Thats right, the telemetry or flight data always show the GPS being used as primary, only the logs reveal presence of the secondary.

  • i use the Navspark-GL as primary GPS and it works great in 3.1 and 3.2, except that I've learnt that the HDOP figures are overly-optimistic compared to the ublox units.  I generally wait until I have an HDOP < 1.8 before flying.

    Oddly I couldn't get it to work as a secondary, at least even when hooked up as secondary the telemetry data doesn't indicate that it's being used, the higher primary ublox HDOP/satellite data comes through all the time.  Haven't look at the logs yet.

  • John, as I have the impression,the MP (flight data screen/logs) doesn´t tell the truth for the G2M1 NMEA output, at least at my setup. (Set to GP messages with the Venus viewer and to NMEA (5) @ MP). It looks great @ the logs being used as secondary, but its not usable as primary or stand alone. Maybe, AC3.2-rcx isn´t able to overwrite its NMEA settings as it does with .ubx setups.

  • Gervais, I haven't used it as primary, but am curious and will try tomorrow. Observing later or long side by side in mission loaner logs shows that there is very little difference in the position solution in my rig, although the hdop difference could be a whole 2 numbers different.
  • @John, here is my G2M1 test setup..

    vfoyeae5.jpgUsing it as 2nd GPS, (GP Talker set,NMEA @ MissionPlanner) it provides outstanding results @ the logs, even better than my reference CSG NEO8


    But as a primary or stand alone...its producing GPS errors and doesn´t work well with AC3.2-rcx. Too bad, it seems that the NMEA output either misses sth. or just doesn´t work with Arducopter.

    Did it work for you as primary ?

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