Kakute F7 AIO S.Port Telemetry

Trying to get telemetry (GPS, Batt voltage, etc.) back to my 9XR Pro via s.port. Works ok in other models, and return RSSI data ok, so I know the radio config is ok. Data being returned to MP via USB, so that’s ok.

I’ve connected s.port to T4, set baud to 57,600 and serial 4 to Frsky pass through (10), but no luck.

Anyone else successfully using s.port on the Kakute F7?

What have I got wrong?



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I don’t have a Kakute F7, and my F7-based Holybro Pixhawk 4 is somewhere on a ship transiting the Indian Ocean atm, I think. But I bet the solution is this :slight_smile:

arducopter code needs added support to control uart inversion. i am trying to convince @tridge to add it for quite a while but it is a bit of work.

for now all you can do to make it work is to use a hardware inverter to feed s.port of your receiver from the uart. response above is what can be done now, but i hope with some time it will work as it does with betaflight - it is a code issue of missing uart control functionality.
ask for it in this thread: https://gitter.im/ArduPilot/ChibiOS

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Why not solder wire to uninverted SPort?

it does not work reliably, with kakute for me it did not work at all. you can try if you have a kakute f7.

plus this univerted r-xsr port pad is tiny and comes of board with a minimal effort. ask @tridge to adjust uart code, there is no reason for arducopter not to be able to do all the same that betafligght does. it is just a matter to control uart to switch inversion and activate half-duplex protocol.

relaistically, with osd showing telemetry it is not critical. but, would be nice indeed to have it working on taranis - to see voltage and other stats, plus yaapu telemetry is very nicely done.

I was also hoping that the telemetry would work as it did in Betaflight but at least understand why it isn’t from Paul’s explanation. I would really like to use FlightDeck as I did with another drone and it would be great to be able to avoid having to get another inverter cable.

Just an update, I decided to get the soldering iron out and used the direct connections as described here…

I connected both ‘A’ and ‘B’ on my X4R-SB, i.e. both RX & TX, and I now have telemetry, including GPS position, on my 9XR Pro. (Serial port 4, option 10)

HTH someone at some point!

Be good to get the inversion in the code, though. Seems such a waste to have a capable board, but then resort to hacks!

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At least the new FrSky R9 MM receiver have the Inverted S.Port… It’s almost impossible to solder this small R9 Slim or R9 Mini, that are the ones I’m using.

Hi, everyone.
I’m trying to use the new parameter SERIAL4_OPTIONS to get inverted serial to get telemetry in Taranis but I did not figured out if it is possible to do it. I’ve setted the parameter to 1 (InvertTx) and telemetry still does not work. Any tip? Does anyone made it work? Thanks.

Hi, download and install ardupilot code from “latest” folder. Use option 10 - to set inversion and half duplex protocol. Solder s.port wire to the tx pin on the usart port you used. Load yaapu7 or yaapu9 script on your taranis. It should work.
It works for sure on kakute f7 but should also work on any f7 FC. F4 FCs only will work if they have hardware inverters and will require custom hwdef configuration.

Hi, Paul. This was my first try and didn’t work. Later I saw this new parameter. Did you change the parameter SERIAL4_OPTIONS (or other number) or no?

Hi, u set that options param to value … Hmm… 7 i think
I am not by computer now

here is the PR with the code change for that feature:

Paul… I didn’t understand… I got this link from Holybro support:

But in the link you passed me, the author said I can use one wire to connect to FrSky Receiver. I’m using R9 Slim and R9 Mini receivers (Some R9 MM on the way). So, I don’t have to connect the SBUS OUT on receiver to RX6 on Kakute? I did not understand this wiring scheme… :frowning:

Can you please tell me all your wiring connections? Thanks again!

Best regards!

Weird info. My “smaller board” (non-AIO) Kakute F7 definitely has an OSD onboard. It’s the regular 7456 used everywhere.

Ok, i am not sure what is a F7 with no osd. I
A usual f7 kakute is set for atducopter having betaflight in mind.
Rx pin on uart6 is set for sbus in. Radio in.
Using last code you xan use uart6 tx also, set inversion option to 7, protocol option to 10 and that will do frsky passthrough telemetry link with taranis radio. You need to load yaapu lua script into radio. Google it for details. I use r-xsr, its s.port pin is inverted, so it needs option 7.

So, one wire is used for radio in - sbus to rx pin on uart6. S.port pin for telemetry goes to tx pin of uart6, and needs uart6 switched to half-duplex inverted.

Man, my setup is exactly as yours, but my receiver is R9 Slim. Maybe this receiver have something different. I already have telemetry working on Pixracer R14 and Navio2, but with Navio2 I don’t use Yaapu yet. I think Holybro docs are wrong. They should put “without pdb”, not osd. I will try with a X series receiver. Thanks again… :+1:

It should not be receiver dependent. You only need tx pin set to half-duplex and protocol 10 for pass-through.

I’ve just tried with a X4R receiver and did now work too… Paul, are you using Taranis with OpenTX 2.2.2 and Yaapu 9? Are you using UART Tx6 for telemetry, as Holybro recommends, or are using another port number?

Can u pls explain connections u made and post your parameters file?
Yes, my setup is same.

I recorded a video showing my connections:

The params file can be downloaded in the link:


Let me know if you need any other information.