Problem connecting Pixhawk and Futaba receiver


Two of my customers have trouble setting up the Pixhawk - I myself have a Pixhawk, but don't use a Futaba receiver, thereby I can't replicate the problem (I would like to find out if the problem is connected to the receiver they use, or something else).

Both use a Futaba R7008SB receiver.
Both managed to upload the Firmware to their Pixhawks - but they are not able to do the radio calibration (the Pixhawk doesn't "see" the receivers, the bars in the calibration are all grey).

They have nothing else connected to the Pixhawk, except receiver (connected to the right port / RC), buzzer, safety switch and USB cable.

The Pixhawk signals via the big LED "pre-arm check failed" (which makes sense ;)

They power the Pixhawk via USB and at the same time with a LiPo (via the Power Module).

The receiver is "found" by the remote, the LEDs are on, the setting of receiver and remote (regarding the use of the SBUS) seems to be right. They use the right port of the receiver to connect to the Pixhawk.

I am happy about any suggestions ...

Thanks a lot in advance


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                • Developer

                  @Tristan: see my latest post here, thanks!

                • Very interesting!  This sbus_decode send back wrong variables?

                • I think this is not only sbus.c problem because all in this file seems like good.(Logic sniffer detected s.bus frame, same speed, same data size in ms, non standard endbyte detected but not used )

                  In s.bus.c file minimum size frame 7ms but in 12CH mode this is only 3.3ms. Maybe ppmsum and dsm check more  than 3.3ms?

                  • This is my sbus.c file.

                    Just check at line 217, here are the changes.



  • On my trial of S-Bus connection to Pixhawk.

    1) Futaba R6303SB:         Good

    2) FrSky  TFR8SB:           Good

    3) Futaba R3008SB:         Fail (S-Bus nor S-Bus2)

    4) FrSky TFR4B               Good

                         *FrSky TFR4B is actually not a S-Bus receiver.

    • Compatibility List of Futaba receiver and Pixhawk


  • I know those who are in the "know",mare claiming the ability to utilize their 7008sb sbus receivers in conjunction with pixhawk via simply connecting ch8/sbus directly to RCIN of pixhawk, but when I try that no signals whatsoever are getting recognized by the radio calibration page and I am beginning to become frustrated. Is there some secret step that I'm accidentally omitting to make this pair of high quality electronics jive with one another? If so, please do tell...
  • Developer


    Please - S.BUS2 is supported by Pixhawk. Here is the line that does decode S.BUS1 or S.BUS2.


    I can only recommend to get in touch with the APM developers (e.g. via the drones-discuss Google group) to check what the status is on a release incorporating this. You could compile the code yourself today and have S.BUS2 going.


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