ArduPilot latest firmware has supported MSP protocol since Sep.02
SERIALn_PROTOCOL = 32, “n” is serial number of UART in ArduPilot hwdef, not the FC UART number. On some flight controllers, serial1 is not equal to UART1, Pls checkout FC manual to get corresponding serial number for each UART.
SERIAL_BAUD = 115
RNGFND_TYPE = 32
FLOW_TYPE = 7
Communication between 3901-L0X module and Flight controller via UART MSP V2 protocol supported by INAV and ArduPilot.
There is no detailed datasheet of MSP V2 protocol.