SERVO_BLH_PORT is documented as “This sets the telemetry port to use for blheli pass-thru”. I thought BlHeli pass-thru went over the signal line, not the telemetry line?
While testing BlHeli_32 pass-thru on a KakuteF7 running 3.7.0-dev I’ve found that if I set SERVO_BLH_PORT to the ESC telemetry port then pass-thru doesn’t work. It only works if this parameter is set to 0.
i think this is a alternate port for the pass thru to connect to, ie connecting blheli sweet on uart zero ie the usb, this means you have to disconnect from mission planner in order to connect blheil sweet. For debugging purposes it may be desirable to send the connection thru a second serial to usb adaptor so you can be connected with both mission planner and blheil sweet.