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FrSky FPort support - testers wanted

post a tlog or onboard log (*.bin file) and also tell us what uart pin you are connected on. I’ll check your parameters

I have it fixed the Telemetry.

R9 Slim +
R9M 2019
X9D +
F765 Wing
AP 4.1.0


And der F-port to TX6-Pin

Can confirm the same thing - 765 wing.

RC_OPTIONS,8 - No telemetry, only control
RC_OPTION,0 - Its all working… very cool :slight_smile:

I can confirm the following working (RC and Telemetry using Yaapu9 Lua on Taranis) :

Pixhawk4 + Frsky RXSR (ACCESS - F.port firmware)
The RXSR is straight wired from S.port pin to Tx on Serial4 (no juggling around with non-inversion pins on receiver). SerialX_OPTIONS=7 does the trick here.


I still have the problem that Telemetry does not recover after RSSI reaching low value (not determined the threshold yet). When signal strength recovered, only the receiver based telemetry (RSSI and RxBT) are coming back up. This was also the case in S.Bus + Frsky passtrhough, not related to this F.port implementation.

Let’s have it ! One wire less !


So does the fport work on pixhawk? I do not, I am very surprised at who works, share details

Hi Ilya,
Details of my setup provided in my post. Pixhawk4.
Let me know what more dtails you´d like.

It does not work for me. I connected the wire from Sport to serial 4. Plus and minus set the settings. Is this enough?

no control no telemetry.
I checked betaflight everything works.

Hi Ilya,
I do not know about the R9 and the inverted/non inverted of the Fport. Your wiring seems ok.

My RXSR: flashed with ACCESS Fport firmware. Pixhawk4 with Arducopter 4.0.2.
S.port now being F.port connected straight to Tx on the UART. Settings of the several parameters as in my earlier post. Where Serialx Options set to 7 does the trick of making it a half duplex line, and the right signal inversions. Just plugged it all in, and have full telemetry and RC control.

Yes, I tried it. But it doesn’t work. i tried telemetry 2. on no

Hi Ilya,
you wire fport in 2 ways:

  • RC control only (no telemetry) by using the RCIN port, this is a “softserial” so no adapters required
  • RC + telemetry by using a serial port, in this configuration you need and inverter/ttl adapter such as this one

how to do this? what settings? how to connect to r9mm?

management works if you connect sbas to rcin, but it looks like it is not fport

earned !!! it was necessary to update the firmware to the latest 403. but there is no telemetry! only management
set RC_OPTIONS to 0 and it worked !!!

Thanks a lot.

presuming you mean plane 4.0.3, then you are not using fport. Plane 4.0.3 does not have fport support. You are probably using SBUS.
To test fport you need to use a ‘latest’ (also known as ‘master’) firmware

Tested on Pixhawk 4mini and R9 Slim+. S.port from receiver connected directly to RC_IN (2pin) on FC.
ArduCopter V4.0.4-dev.


Work ok with telemetry. Sometimes when I do range check RSSI displayed in Mission Planer drop immediately but when set normal power back RSSI rise on MP after few seconds. When on Yaapu telemetry RSSI is 100 on MP is 39.

Tried FPort on my old Omnibus F4 pro copter with ArduCopter V4.0.4-dev (0f7de04d) with R9MM receiver and it randomly reboots with the same watchdog data, but only when I bind it in 8 channel mode with telemetry enabled. If i bind the receiver in 8 channel mode with no telemetry the FC doesn’t reboot and control works fine over FPort. The first two reboots caught me mid air :smile:
Here’s the data from the ones that happened when flying (they’re identical):

Task 4 FL 101 FT 3 FA 3758157112 FP 180 ICSR 4196355

my parameters:

Connected the SBUS wire back and switched to SERIAL1_PROTOCOL=10, no more reboots since then.

Any telemetry or dataflash logs available?

Can your reproduce on the bench?


as Peter says, we’d really like the logs

Yes, happens on the bench as well. I tried putting ferrite choke on the receiver wires, unplugged the GPS/compass, powered via USB or main battery, turned VTX off, even changed the receiver antenna, still reboots.

I’ve uploaded logs of a reboot during indoor hover, let me know if you need more logs.

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Great, thanks! We’re investigating here ATM.

Could we ask you to try disabling various bits and pieces to see if they
cause the problem to go away, please? Just to help us narrow down where
the problem might be.

So, for example

  • disable the OSD
  • disable battery monitoring

Poking me on skype (peterjdbarker) might help shorten the loop.


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