FrSky XM+ receiver soldered to the SBUS per the diagram. FC is a Diatone Mamba F405 Mk2.

I have UART1 set to serial Rx, the config tab is set for serial-based Rx (SBUS) and I'm having no luck. It is bound properly, wired properly and configured properly. I ordered a new XM+ and swapped it in today and still no dice. 

As far as I know this board has an inverter circuit, otherwise it wouldn't advertise SBUS. Had no issues with my old Fireworks F4 board. 

Here is the wiring. It isn't pretty because I've had to remove it so many times. 




Here is my Betaflight dump: https://pastebin.com/5y1NkRL6

Any ideas? I've been grounded for weeks. Last week it was a broken ESC on an AIO board.

So you have solid green light on the XM+.

Try this.

set serialrx_halfduplex = ON
Save

No dice. The light is more of a fast flickering green than solid, but it is a brand new Rx.

That is interesting. This is happening on both receiver with the green light?

Can you try different combinations of

set serialrx_halfduplex and
set serialrx_inverted

Both receivers, yes. Inverter was off by default, switching variations of those settings had no change

I ended up just bypassing the inverter circuit on the receiver and tied it into uart6. Works now. Super annoying.

https://www.getfpv.com/learn/fpv-diy-rep...receivers/

That is what I was going to suggest next. I wonder if SBUS will work with hack signal.

Works great! Finally got to put the top plate on after 2 weeks haha. Thank you for all your help.

There must be something wrong with UART1 (or the inverter on UART1) on your particular FC because we've had other people on here successfully using the SBUS pad on the Mamba F405 flight controllers for FrSky receivers with no such issues.

That's been my best guess. This is the second time I've had to bypass the signal pad on an XM+ due to damaged flight controllers.

On the plus side I now have 2 spare receivers. Just happy to have it done, this thing rips!

Is it possible UART1 is mapped to something else?

(29-May-2020, 12:16 AM)Herp Derpula Wrote: Is it possible UART1 is mapped to something else?

It is not remap somewhere else.

(28-May-2020, 11:42 PM)SnowLeopardFPV Wrote: There must be something wrong with UART1 (or the inverter on UART1) on your particular FC because we've had other people on here successfully using the SBUS pad on the Mamba F405 flight controllers for FrSky receivers with no such issues.

My Mamba SBUS works well. Even the Inverter switch works.

Hardware issues happen. Just last week my 30A iFlight AIO lost an ESC on the second flight for no obvious reason. I have a pile of dead parts, a lot of which were DOA. It happens.