Please note that Babyhawk Femto has a rear facing USB port, where as the standard Femto has the USB port is has a USB facing the side of the board orientation. 

Features

• STM32F303 CPU
• MPU9250 accelerometer/gyro/compass (connected via SPI)
• 2-6S LiPo battery
• Integrated 5V/3A BEC
• Dedicated Sbus and serial RX with 5v, Spektrum 1024/2048, SBUS, XBUS, SumD and SumH RX with built-in inverter
• 6Supports direct connection of 3.3v Spektrum Satellite receivers
• Telemetry support (FrSky telemetry, smart-port, and HoTT telemetry)
• Dedicated PPM receiver input
• Buzzer support
• Dedicated output for programmable LEDs - great for orientation, racing and night flying. (Currently mutually exclusive with the Transponder)
• BLHeli Passthrough ready?connect BLheli suite?
• 2.0 mm pin headers
• 80A Current tolerance (PDB)
• Integrated Battery monitoring
• Use all the features all the time; e.g. Connect your USB + SmartPort + SBus + LED Strip + Battery Monitoring + 4 motors - all at the same time!
• 20x20mm board
• Weight 2.2 grams
• UART3 ?RX3?
• Use for Spektrum Satellite RX, Spektrum 1024/2048, SBUS, XBUS, SumD and SumH RX, etc.
• UART2/PPM - Serial RX or PPM RX + Telemetry
• Use RX2 as PPM receiver. Use TX2 as telemetry output when using PPM.