I have a Speedybee f405 wing using ardupilot. Ive used tx4 for FRsky pass through telemetry to my R9sx 900mhz sbus and sport Rx. So sbus is on rx2 ( Tx2 is no good for my sport telemetry hence using tx4) . Serial 3 is GPS. Serial 5 vtx and serial 6 wireless board. Hence I’ve kind of run out of parts and I want to use a UART to switch on and off my runcam split 4 recording remotely. So I am wondering can I use serial 1 which is where an elrs Rx would normally connect? I’ve tried setting it to runcam protocol and assigned a tx channel. Any ideas please?