Where did I seen this? Well, it's from the BrainFPV Helpdesk:
"The 3 wires from the S.Bus receiver need to be connected to the GND, 5V,
and RX pins (GND: 1, 5V: 2, RX: 4) of the MainPort. The S.Bus signal is
3.3V, so it won't blow up the Brain
. When setting it up, make sure that
the RxPort doesn't have a PWM or PPM mode selected; otherwise the S.Bus
receiver won't work."
And no, switching the receiver Port to pwm out, doesn't help that much, because you have one serial port blocked with the s.bus, and another one gone - that of the receiver port in PPM/UART/PWM-Out - Mode. I can conncet GPS with that still, but no external Compass (no I2C left) und no telemetry or bluetooth module.
I like the brain becaus of his OSD, but I used a Quanton before - much more space, much more (standard) pins... I learned to miss that on the brainFPV. Want to have a brainWithLotsOfPins...
I think' Ill use an s.bus to PPM conversion, but to be honest, that doesn't look like an elegant solution.