• Robert, did you follow the sensor setup for airspeed and groundspeed  detailed in the wiki? You need to configure the sensors to be in knots, then on the LUA page you can choose the units of choice for display. In my setup the airspeed on the LUA page matches mission planner exactly - for ground and air speed.

    As for Angle of Attack mentioned yesterday - the data I described isn't accurately the AoA, but rather the pitch attitude, as to get the AoA, you need to know the angle of the wind flow onto the underside of the wing, but we don't have any way to measure this through any sensor, so I don't think this would be an easy job to calculate this accurately.

  • ok.  I got to fly the plane today and things turned out good with one issue.  It seems that the airspeed units of measure seem to be wrong.  I like to have everything in kts but it seems mission planner/arduplane have a hard time being consistent with the units.  Any how, I can see that my speed on taranis was half of what mission planner says I was going.  I tend to believe mission planner.  For instance, I did some stall testing and the stall speed according to the Taranis is about 9kts which is wrong.  The plane is a Telemaster and I know it flies slow but I am doubtful it is that slow.  I suspect 9 is a meter/second reading.  GS has me stalling around 18kts which is much more believable.  I tried changing the units on the sensors but that made the gap even wider.  Anyone notice this?  Is this a problem with the units that arduplane is feeding to the teeny?  Or is this a conversion problem in the Sketch code?  Or is this a unit issue in the Lua code?  I have my Lua script setup for KTs as well as my sensors.

    Thx for the help so far.


  • By AoA you mean the pitch angle? Or the glide angle? If pitch angle, then I imagine this could be calculated in LUA code from the pitch value displayed by A4 (too complex for a calculated sensor). I've never really paid attention to this sensor but I'm sure you could work it out from the info in the wiki and by experimenting to really understand those numbers.

    The wiki describes A4 as: Pitch angle from -Pi/2 to +Pi/2 radians, converted to a value between 0 and 1024. Now if I am translating this correctly, this suggests that a value of 0 would represent pitch down of 90deg, 512 would be level and 1024 would be pitch up of 90deg. 

  • Paul

    I got a lot more of it worked out.  I did a reload of the code on Teensy and now I get a single GPS that updates.

    I also see where there is a plane option on the lau script.

    I am running AP 3.8.2.

    Ii will do some testing on what I have now.  Is there a way to display AoA data on the screen?  Do I need to create a custom sensor with a calculation?

    Thank you for your time.


  • Robert, I'm still trying to figure out what you are doing wrong here. If you can please answer a few questions, this might help:

    1. Are you running a Taranis X9 radio? So Taranis X9D Plus for instance? This has been written specifically for this, although the telemetry sensors should be picked up by OpenTx 2.1 or newer (works fine on 2.2.0 for instance) on any radio to be honest running OpenTx 2.1 or newer (the LUA only works on the Original Taranis X9D or X9D+ though).
    2. On the Telemetry sensors page (at the bottom) be sure that 'Ignore Instances' is not checked before you do the discovery (in Companion this is called 'Disable multi sensor handling').
    3. Can I also please check that your "Telemetry type" is set to "FrSky S.PORT" at the top of the sensors page.
    4. Can you please explain your plane configuration - I.e. do you have only the teensy on the smart port connection, or do you have any other FrSky smartport sensors daisy chained? If so, what are they?
    5. You are running ArduPilot (and not PX4 flight stack)? What version of AP?

    Baud should be 57600

    The project is written for both Copter and Plane (assuming you're using the newer versions) the latest version in my repo here: includes the configuration page within the LUA script which allows you to choose between Copter/Plane - making the correct selection here ensures that the correct flight modes are displayed/called. This is all on the LUA side though (which is all about setting up your SD card contents), so lets try to concentrate on getting the Teensy/sensor part working first. I am running this on a plane running AP 3.71 (not tried 3.8 yet).

    Last thing, what does the Options section of the teensy code look like in your configuration? I'm referring to the Addons/Options section in MavLink_FrSkySPort.ino

    Cheers, Paul

    APM MavLink to FrSky S.Port converter. Contribute to athertop/MavLink_FrSkySPort development by creating an account on GitHub.
  • I see a host of other sensors such ast VSPD, VFAS Accx, AccY, AccZ, heading.  I even see GALT.  but no GPS sensor.  Even the mag works.  My groundstation seems to read the GPS fine.

    I deleted all sensors and tried again.  This time the GPS showed up twice but neither works.  One line has latitude while the has longditude.  They are under different IDs too.  

    I even tried changing the baud rate to 19 but that made all sensors double discover.

    I see the lua scripts seem to be more copter oriented.  Does someone have a script set for planes?


  • Robert, if you have followed the wiki then if you do a sensor discovery, you should see a sensor called simply GPS. You need to do this through a discovery (and not by adding manually into Taranis or through Companion - as neither will work).
  • I think I am missing the supporting LUA scripts.  I will have to work on that tonight and try again.

  • Paul

    Thx for the reply.  I got Teensy installed and Taranis configured but I cannot seem to locate the GPS as a sensor.  Is this something that the program is not designed to do?  I can see the accel x/y/z, galt, alt, current, etc but nothing reading from the GPS.  Any ideas on where to look for this?


  • I just placed an order for some DF13 cables.  Seems I can only find them in 20cm lengths.  Does anyone have them longer?  Maybe 24" so I can really relocate a gps?

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