1. First of all, check the connection and setting by referring to
2. Make sure the firmware version of your flight controller is up to date.
- BetaFlight version 3.2.0 or above
- CleanFlight version 2.1.0 or above
3. Tx, Rx, GND should be well connected to a UART's Rx, Tx, GND of your Flight Controller:
4. Make sure your transmitter(Tx) is bounded well with the receiver(Rx). In other words, you can arm/disarm your quad.
5. Make sure you set the correct Receiver Mode
on your Flight Controller Configurator:
6. Make sure you enable the correct Serial Rx port on your Flight Controller Configurator:
7. Make sure Split's OSD MENU > GENERAL > Control Mode is Flight Control(not PWM):
8. The switches should be correctly assigned on your transmitter(Tx) and well configured in the flight controller configurator.
That is to say, you can view the change on the Mode page when you switch on the switches you configured.