Yapuu telemetry - Arducopter serial ports configuration not clear


This post is about configuring the Yapuu passthrough telemetry on Arducopter with Pixhawk and a Frsky X4R receiver, on a radiomaster TX16S transmitter.

On the Arducopter configuration side, the documentation page is out of date as it says to configure “serial#_protocol” to the value of 10 (for passthrough). My problem is that there are new undocumented “Serial” parameters in Arducopter : see screenshot below

There are these “Serial_pass1” and “Serial_pass2” parameters which seem to have a purpose for passthrough but no explanation on how to configure these two parameters to have passthrough telemetry from my FrSky X4R (Sbus) ?
Also, what Serial# (0, 1 2, …) port has to be configured with Serial#_protocol" to 10 for a X4R receiver connected with SBUS on pixhawk (it is not connected to a serial port)

If anyone has done it succesfully, please help !


You do nothing with the SERIAL_PASSx parameters. They have nothing to do with telemetry passthru. For Yapuu you must use protocol 10. The serial port depends on which one you have connected the Rx to…

Also with a Pixhawk you will need a hardware inverter between the Rx and the FC.

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Thanks Dave for this info. I’m using a X4R (Frsky) receiver which is connected to SBUS (not to a serial port) which is RCIn on the PIxhawk servo pins. To what serial port corresponds RC In/Sbus on a Pixhawk ?

It doesn’t work that way. Unless you have an Fport version flashed to the receiver RC and telemetry are on are 2 different ports. RC out of the Sbus port and Telemetry in to the Sport. Fport on the discontinued X4R is Beta and I believe unreliable so you will want to use the Sport route. So as is shown in the 1st graphic in the link above get yourself a bi-directional inverter and connect it between the Sport and a serial port.

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If I swap my old pixhawk with a H7 cpu based flight controller, I guess I will not need the cable, right ?

Right. H7’s have software configurable ports with respect to inversion/duplex.

ok that is what I will then do. That is also a good excuse to purchase more gear :slight_smile: