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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Hi Luis

             i am using APM 2.6  firmware  is the latest uploaded in mission planer

mision planer reports pitch/ roll ok.

I am sure that the problem is in the teensy sketch because if i substitute fixed values in the sketch  for pitch /roll then  the display is correct on taranis but static

as I said the condition for switch case  MAVLINK_MSG_ID_ATTITUDE:     //30

is never true  so values are not updated


You'll have to check the complete Mavlink stream to see what comes on 


i move the cell-min info functionality into a model script. now user can configure several parameter.

also it is possible to configure a alarm horn if critical voltage is reached.

configureable is
  • critical alarm level in mV. default 3400V
  • use Horn 0 - 3. 0 is no horn and 1-3 different horn samples. default 0
  • warn level in mV. default 3500mV
  • repeattime in seconds for warn level and critical alarm. default is 4seconds
  • info cel-min drop voltage in mV. this repeat info cell-min voltage each time cell drop this value. default 100mV

hopefully that this is also usefully for other "battery is empty paranoid people" like me:)



Hi Luis

           I understand all that you have said and thanks for the advise.

I did not get this  attitude debug section to work (all the other ones do work)

 I think this is because  msg.msgid is never 30 so case switch is not satisfied

msg.msgid numbers  received are 17,29,150,1,152,42,24,62,162,74,

does   this mean that my APM 2.6 is not sending attitude  (msg.msgid=30)  data ??

mission planer reports attitude correctly

any way ,the sun is out now going flying!!


I don't have a APM, but Christian has and he hasn't had issues with Attitude values.

Are you running ArduCopter 3.1.x or 3.2.x ??

H Luis

       I am running ArduCopter 3.1.5

Hi Luis


re flashed APM2.6 with an earlier firm 3.1.2. and pitch/roll is working!!?

your lua scrip is excellent

and teensy code is also working well

Thanks to All


Hi Luis

   This is getting weird!

   pitch roll is only transmitted to teensy after connecting and disconnecting

   to mission planer ??

so this is the situation now

APM2.6 v3.1.2,

usb unplugged flight battery boot up = no pitch/roll message  (other messages ok)

plug in usb  connect to mision planer= no  frsky telemtry data(same port?)

disconect from pc   all work fine   ??

My programing skills are very limited perhaps someone has the answer?




      seems like another code has to be sent to APM to  get it to output pitch and roll??


hi luis,

maybe i have a bug with opentx 2.0.12 by using the telem1.lua script. see https://github.com/opentx/opentx/issues/1834

my trani change logical switches after a long uptime by it self.

so i decide to remove all bmp files from telemetry screen by replacing against asci chars.

also i lower the use of garbage collector by removing string concat operations.

at least i move all variable initialisation from functions to script head. this is nothing i like, but i got this tip to reduce script problems.

if interested on this, my changed file is located here https://github.com/wolkstein/MavLink_FrSkySPort/blob/e2b1f67b0e350d...

info, in this script i also remove the engaged messages because i do not need them. but they are not the problem.



Hi Wolke

Thanks for the warning.

I really believe that something strange is happening on OpenTX 2.012 and even on later builds. I began having audio stuttering problems when an SD card had many files, and later I saw some reboots from the radio. Not sure how related the audio problems were (I could work around these by carefully copying the files to the SDCard) with the reboots.

I've opened also an issue on OpenTX 


I don't think that it is related with the concatenation issues or too many bmp's being used or even the variable initializations. No way to prove this but just a feeling.

Unfortunately these problems are not easy to reproduce, and I don't have a good way of debugging on the radio, because on the simulator things are not the same....

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