INAV 2.0.0 RC2 doesn't work with XSR-M S.Port unless smartport_uart_unidir = ON

[teckel12]

Board and Version

Omnibus F4 Pro
INAV/OMNIBUSF4PRO 2.0.0 Jul 6 2018 / 09:28:45 (afc5602)
It's custom compiled, with the only inclusion being #3519, same result with downloaded release RC2

Behavior

No S.Port telemetry from INAV from FrSky XSR-M receiver (latest firmware). Downgraded to INAV 1.9.1 and S.Port telemetry worked again. Flashed back INAV 2.0.0 RC2 and it didn't work. Replaced XSR-M receiver with a backup and it still didn't work. Works fine on other quad running 2.0.0 RC2 (same build) and similar hardware except for different receiver X4R-SB.

Blackbox logs/Config (.ZIP) where problem occurs

https://pastebin.com/xp5iaxHC

[teckel12]

Got it working, but with a sacrifice. With 2.0.0 RC2 and the XSR-M/E you need to set smartport_uart_unidir = ON for S.Port telemetry to work. On a different quad with the same firmware, same FC, and almost exactly the same settings, but using an X4R-SB receiver I have smartport_uart_unidir = OFF. Both receivers are connected exactly the same way, to the SBUS port and S.Port connected to soft serial via the ch5/ch6 pads. With INAV 1.9.1 I had smartport_uart_unidir = OFF and bidirectional S.Port worked with the BetaFlight PID Lua Script.

I believe what this means is that with INAV 2.0.0 RC, the XSR-M/E (at least when using soft serial) can't do bidirectional S.Port as well as smartport_uart_unidir = ON being required.

[fiam]

@teckel12 I've just set up an XSR (note the different RX) with an OMNIBUSF4PRO and it works with S.Port over softwareserial with smartport_uart_unidir = OFF. Could you use DEBUG_TRACE() to figure out if the port is being open properly and if the S.Port driver is getting the requests from the RX?

[teckel12]

@fiam will do... Note that my X4R-SB also works fine with smartport_uart_unidir = OFF. Also note that I'm running S.Port via SS in all cases.

[teckel12]

@fiam Did a build with DEBUG=GDB and flashed but that's as far as I got. I was expecting more of log, but it seems that it uses a debugger of some kind? I've never needed to use a debugger so maybe this is where it's beyond my experience. I'm old, so I learned to program before we had debugging tools. I avoid writing bugs, so I've never needed a debugger, I guess till now.

Is this what's needed?: https://gnu-mcu-eclipse.github.io/debug/install/

If so, I could give it a go. But like I said, I've never used a debugger so my effectiveness would probably be low.

[fiam]

@teckel12 Don't worry, you don't need to set up a full-fledged debugger. Use https://github.com/fiam/msp-tool to connect to the FC and it will print debug messages. Then change the code to use DEBUG_TRACE() to print stuff.

[teckel12]

👍 Will give it a go.

[teckel12]

Now works fine with 2.0.0 on this quad with the smartport_uart_unidir = OFF, so closing...