Hello all,

I have naze32 rev5 board and FrSky XSR receiver. I am using CPPM and thus the UART2 port is free on my board.

I connected S.Port to RC3 pin on naze (UART2 TX pin).
After quite a lot of tries, I am still not able to make the telemetry running.

My question are:
It is possible to make the telemetry running on UART2 port? (Or shall I use SoftSerial?)
Is it necessary to short RC3 and RC4 pins? (Why is there RX necessary?)
Is it necessary to place between RC3 and RC4 diode or resistor? (I read that sometimes it helps.)

If someone make it running, could you please give here the picture with connection and with a setting used in BetaFlight / CleanFlight?

Hi,

1. Yes, not sure how you have setup serial port but under Port tab, telemetry, you should select "Smart port" and "auto", and  set select_telemetr_inversion = ON
2. Yes, the reason being SmartPort telemetry uses a single wire for both TX and RX. It’s a half-duplex protocol. You can emulate this using soft-serial by hooking TX and RX up to the same pin on the receiver
3. It's recommended to add a diode between TX and RX. Pete explained it very well in my SBUS and Smart port tutorial:

Quote:For telemetry to be guaranteed on the Smart-Port you will need a diode (a resistor of a few hundred ohms into the 10’s of K would probably work too) from TX on the flight controller (RC6 in this guide). This is mentioned in the comments as the diode tip. For some it will work without because of device tolerance, essentially without the diode or resistor, you’re driving logic 1 from the receiver to a logic 0 from the flight controller, whichever has the weaker current limit will loose. Logic transistions ideally should be 0 to 3V3, I was getting 0 to 1V when linking which doesn’t work as the RX on the flight controller does not ever see a logic one and hence no data requested is ever sent. Apart from that, this guide is golden.