To let the flight controller know which serial port your receiver or VTx is connected to, you need to configure these ports in the Ports / Serial Interface tab. Let’s start from the left and work our way to the right.
Configuration / MSP
In the Configuration/MSP column, you set the ports that communicate with the FC via MSP. This includes the USB port, which is why the first row is locked. If you turned this slider to Off, you wouldn’t be able to communicate with the FC through the configurator anymore.
But which other sliders need to be turned on? That depends on your FC and the devices connected to it. On FCs with a Bluetooth module, MSP is often enabled on UART4—for the same reason it’s enabled for USB VCP.
If you have a digital VTx in your build and want to use OSD, you must enable MSP for the UART your DJI, Walksnail, or HDZero VTx is connected to, and also select VTX (MSP + Display Port) in the Peripherals dropdown.
Serial Receiver
As the name suggests, here you set which UART your radio receiver is connected to. If it’s soldered to Rx2 and Tx2, activate the slider for UART2. If you used a connector and aren’t sure which one… [text cuts off, probably “activate the correct UART”].
Telemetry Output
If you use telemetry, for example via ELRS or MavLink, the FC also needs to know this. Activate the corresponding telemetry protocol and set the correct baud rate.
Sensor Input
If you have a GPS installed, or if your ESC communicates via a Tx pin with the FC, you need to configure it here. As before, enable the function in the row of the corresponding UART.
Peripherals
All other devices are configured in this column. This is especially important for analog VTx with Smart Audio or IRC-Tramp protocols connected to a Tx pin of the FC, so the OSD can change transmitter settings. For digital VTx, just set MSP + Display Port.
90% of peripherals can run without adjusting the baud rate. If it still doesn’t work, check the device manual to see if a different baud rate is required.
Example:
On this flight controller, the following devices are connected: