Betaflight ports: MSP, serial RX, GPS and the other UART jobs

A UART has two wires, TX and RX, and it can only speak one serial stream at a time. The groups stop you assigning two jobs that would both need that stream. MSP can share the port in the way the firmware allows, which is why it is its own switch. Serial RX is its own switch too, and only on a hardware UART. USB is kept for the configurator.

The choice is stored as bits on the port. Picking a new function in a group clears the other functions in that group first, then sets the one you picked. Disabled clears the group. Baud is stored separately for MSP, GPS-class sensors, telemetry and peripherals, and the row appears only when a function in that group is active.

Turning on serial RX reserves the UART for the receiver. It does not choose CRSF, SBUS, iBus or the other protocols. Those are on the Receiver tab, and they have to match the receiver you actually soldered. ExpressLRS and Crossfire use a serial protocol, usually CRSF, on this UART. The binding phrase for a UART ExpressLRS receiver is not on the Ports tab. It is the ExpressLRS tool, over the receiver's Wi-Fi, in the phone app.

If the stick bars on the Receiver tab stay still, check this switch first, then the protocol, then the physical TX-to-RX crossing: the receiver's TX pad goes to the flight controller's RX pad.

GPS is a sensor-input choice. After you save it, open the GPS tab and turn the GPS feature on, then pick the protocol and baud behaviour there. The Ports baud and the GPS tab baud have to agree with the module. ESC sensor is the serial RPM wire some ESCs use instead of bidirectional DShot. Benewake LiDAR is the rangefinder choice on Betaflight.

Telemetry is the stream back to the radio: SmartPort, CRSF is not in this list because CRSF rides the serial RX port, and the radio protocols here are FrSky, HoTT, LTM, SmartPort, MAVLink and iBus. Pick the one your radio's receiver actually speaks. A second telemetry wire on a different UART is a different card.

SmartAudio, IRC Tramp and MSP plus DisplayPort are peripherals. The VTX tab uses that UART once it is assigned. Putting SmartAudio on the wrong UART is why a video transmitter stays at the default channel. RunCam device control and FrSky OSD are the other peripheral choices on Betaflight.

Blackbox as a peripheral is an external logger on a UART, not the onboard flash chip. Onboard logging is the Blackbox tab. Do not assign the Blackbox peripheral unless you have that logger.

INAV's telemetry list adds a SIM text function and SmartPort master. Sensors add a rangefinder and optical flow. Peripherals add MSP DisplayPort, DJI FPV, ESC telemetry, SBUS output, a gimbal, a head tracker and a log function. The card layout is the same: one choice per group, baud when the function needs it, MSP kept on for USB.

INAV 8 drops some older function bits. FlySpark hides those bits on INAV 8 so you are not offered a function the firmware removed. If a device from an older guide is missing, it is because this firmware does not have that function, not because the port is broken.

Save the ports, then reboot when the save bar asks. A UART change often does not apply to the running firmware until that reboot, and the configurator may disconnect if you changed the port you were using. Come back on USB, open the Receiver tab, and move the sticks before you solder anything else. A Bluetooth module or a Wi-Fi MSP bridge also needs MSP enabled on the UART it is wired to, at a baud both ends share. USB itself does not need that, because its MSP switch cannot be turned off.