Add SOFTSERIAL support on TX6 for OMNIBUSF4V3 target

[krzysztofmatula]

Based on #3033
Verified by using S.BUS on RX6 and LTM telemetry on TX6 (SOFTSERIAL1).
When the SOFTSERIAL1 is not assigned any function in the Ports tab, UART6 works normally, as a bi-directional HW port.

[krzysztofmatula]

Just a note that this change has been flight-tested and works well for me.

[leonard4]

Tried this lastnight with an R9 Slim, was unable to get it to work. Did you have to flip duplex or telemetry inversion with the S.Port signal? I enabled soft serial then set the sensor to "Smart Port" on SoftSerial1, was there anything else you had to change?

[krzysztofmatula]

@leonard4 I was actually testing LTM not S.Port. To make it work I just enabled the soft serial feature and assigned the "LTM" to SoftSerial1 and set it to 57600 baud. Nothing more.

On a related change for different board (#3033) S.Port is said to work, yet I'm not sure if additional inversion need to be set up or not. Maybe the author (David-VG) could say more.

[leonard4]

Gotcha, thanks for the response.

[fiam]

@krzysztofmatula It would be better if you defined SOFTSERIAL_1_RX_PIN to PC6 too. That way the soft serial port can also be used as an RX only port.

[krzysztofmatula]

@fiam Agree it could be useful. I'll verify and provide update shortly.

[littlbox]

Tried softserial on uart6 (tx6) with smartaudio and it's not working. Has anyone tested it?