Hi all,

I just bought an FrSky Taranis for my quad copter and needed to get the Mavlink data up on the Taranis LCD telemetry display. So here is my solution using a Teensy3.1 as a converter between MavLink and the S.Port on FrSky X8R.

See attached file below...

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Teensy flashing slowly and not a steady light for some reason! =/

Does one have to enable something or change settings in APM for it to work?

  1. switch to telemetry screen before you power the model. than the occasional Telem1; script syntax error never happens. this is a workaround.
  2. in MavLink_FrSkySPort.ino line 224 "_MavLinkSerial.begin(57600);" baud-rate settings are default at 57600. is this corresponding with your flight controller mavlink baud-rate?
  3. did you connect teensy rx2&tx2. if you use for example also an 3dr radio, it make more sense not connecting teensy tx2.
  4. did you setup your taranis correctly. in model-setup internal rf mode must be "D16"

all should be setup correctly. Using a CX-20 with apm in it, but telemetry works with it so this should work. Is it serial baudrate 1 or 2 that needs to be 57600 btw?

Other than that, no extra radio etc. TX/RX 2 connected, D16 mode on taranis etc.

APM-planner says Serial baudrate 1 = 57600 and serial baudrate 2 cant be changed from 1600.  But the port available should be the 1.

As seen on this Picture, no odd pins, just the ones needed. So this is a mystery, plenty using this for regular telemetry, so it should work. Anything else that can cause issues?  Slowly flashing led on the teensy so something there is odd?


I am running the teensy with the lua script and will be adding landing gear retracts to my hexacopter on channel 9, i am trying to work out a good way to command the retracts up and down.

I am thinking that the script may be a good way to tell the retracts to go up (when the altitude is higher than 1meter) and lower the retracts when altitude is less than 1 meter or when flight mode is RTL or Land.

Would this work?

if the teensy led is flashing slowly no mavlink data is received. please only connect the telemetry TX pin from your flieghtcontroller to the RX2 pin on teensy. and do not connect the teensy TX2 to the flightcontroller telemetry RX pin. this is not needed because you only receive mavlink with the teensy.

Finally got all working, had to make some smaller "mods" since the OEM-APM I have doesnt work as original APM :)

But to the issues, HDOP is very odd, fluctuating between some values far from correct. APM says 1.5 and taranis goes between 7-8 :)

Great job !

I have installed it on my taranis, but I would remove the single_cell fonctions as I will not make the teensy mod whith the resistors : will it be enough to comment the line 87 in MavLink_FrSkySPort.ino :


And I don't understand how to get the battery capacity in Wh ? I have a lipo 4S 5000 mAH...how many Wh sould it deliver ?

Last question : in the teensy mod schematic it is write "not connect the lipo-balancer gnd-line to the teensy board directly", but it's also write "this both GND must be the same" : so they must be connected ?



Apologies for not reasing 69 pages, this may already be answered somewhere

Do I need to use all three lines on the telemetry end? I already have XBee which I would like to maintain, but use this in parallel sniffing the data from arducopter, and would also like to only use teensy without plugging/unplugging the xbee side for when I don't want to take xbees and tablets etc. Will this work? I duess if there is some two way comms on mavlink it will not?



ok, this answers my question I already posted :)

should have read the thread

too late to edit, spotted the answer in the thead...only page 2 too...shame on me for not reading :)

I have a proposed feature which should be easy to implement: 

Landing gear trigger based on mavlink altitude, RTL, failsafe and error messages. 

OK so I have had a very quick look at the code, its been a while since I did any code and I wasn't very good at it when I did :).

What I would like is as I said above to use with xbee, but sometimes I won't use the xbee, so they won't be there to send the mavlink requests.

So I am wondering....if the code detects if mavlink messages are being received before it requests them. I see there is a section that checks and counts heart beat messages. I could probably get my head around updating to do the above eventually, but before I start hacking...is there an easy way to make the serial output high impedance so that it doesn't affect the xbee tx output if it is being used. I guess I need to make the TX2 output an input. Are these the 



parts or are these for other IO?

Any pointers would be appreciated.



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