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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Cheers Wolke, my bodge seems to work after doing some testing, but will do it your way next time I look at it.

Confirmed - FVLSS works as normal, but I get no voltage readings from the APM PM. I do get current, but not voltage. Would love to know how to get voltage from the PM.

Why not use the FLVSS voltage (cells)? 

I can't read the APM volatage at the same time as current using a VR Ubrain, hence my using the FVLSS in the first place.

Because one of the advantages of this solution is the reduced weight, price and complexity it offers over buying genuine frsky components. It also means nothing to add to balance ports, which is an easy step to forget.

ah ok....I confused you with someone who replied to me before. Without FVLSS the defaulr 1.3 teensy code should show volts if you are using a pm. Are you getting Volts in your log files?


maybe some words to clear confusion with sensor SMART PORT ID's.

each SMART PORT Sensor acts with his own unique physical ID.

found this in frsky FLVSS sensor pdf

ID Set up
Each type of FrSky Smart Port enabled sensor has its unique physical ID. The default
physical ID for this sensor is 02. The ID number could be changed by FrSky Servo
Channel Changer.

the teensy emulate at least seven SMART PORT Sensors.

Defined SMARTPORT SENSORS for this Project.

#define SENSOR_ID_VARIO 0x00 // 0
#define SENSOR_ID_FLVSS 0xA1 // 1
#define SENSOR_ID_FAS 0x22 // 2
#define SENSOR_ID_GPS 0x83 // 3
#define SENSOR_ID_RPM 0xE4 // 4
#define SENSOR_ID_SP2UH 0x45 // 5
#define SENSOR_ID_SP2UR 0xC6 // 6

This mean it is not possible to use the Teensy together with for example an separate FLVSS Sensor, because in this case both sensors try to share one unique address.

Next is that most ports of this "MavLink to FrSky X8R S.Port converter" use FAS and FLVSS. FAS is used to transmit Voltage and Current. Both of this values are reported via mavlink from your APM or Pixhawk. This are the values from Voltage and Currentsensor inputs from Flight controller. Most people use the default 3dr power module or an Atto Pilot current sensor and so on.

FLVSS on teensy is mostly used to transmit cellvoltage. in most ports available here, this is simply the PM reported Voltage divided by cell count. my port https://github.com/wolkstein/MavLink_FrSkySPort also add real cell voltage to the Teensy like an FLVSS sensor because it use Teensy A0-A5 to read real cellvoltage connected via an resitor networt to battery balancer plug.

this mean, if you use the SMART PORT with other FrSky Smart Port sensors or directly connected to Flight Controller (PIXHAWK for example can do this) and at least with one of this "MavLink to FrSky X8R S.Port converter" powerd via teensy or other boards, it is important that you not share unique SMART PORT ID's on different sources connected to the same SMART PORT.

You can use the Teensy together with an for example FLVSS Sensor, bus in this case you must undefine FLVSS in teensy code. and you have to know that FAS will also send via teensy. and in this case you read APM PM values for FAS Voltage and Current. FLVSS only transmit cell voltage.



That all makes sense, but I'm using a default 1.3 install on the teensy and getting perfect data from the FLVSS, and only current from the APM feed (no voltage).

I'll need to go check my setup. I might be doing something wrong, but can't think what.

Do I need to set my voltage sensor on Taranis to FAS? It might be that.

Why would you want voltage from PM? You mean the 5V or 3.3V goin into the FC?

I'm using teensy and FLVSS without any problems. If I remember correctly I commented out the FLVSS related lines in the teensy code just to be sure. Could not be happier with the setup :)

perform all the steps and I can not see the screen with the lua script, still see the classic screen.

Hello Wolke, I use your S-C-L-V-RC (with lines 87 and 88 commented ;-)).

I't a very good job, all is working as it should : big thanks !

Just one more thing is missing to get the even : a second telemetry screen showing a ring buffer of  the XX last messages comming from the arducopter via mavlinkto frsky (status messages, warnings...)

Thanks again for your work !


This report would have more information with
"Show verbose output during compilation"
enabled in File > Preferences.
Arduino: 1.0.6 + Td: 1.20 (Windows 7), Board: "Teensy 3.1"
MavLink_FrSkySPort.ino:47:25: fatal error: GCS_MAVLink.h: No such file or directory
compilation terminated.
 Hi guys, I get this message, when trying to compile, ANy ideas what could be wrong.

I am trying to add some commands to the end of the script to make landing gear retracts lower when armed and under a certain altitude. 

What format is the baro altitude numbers in? (100cm or 1m)

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