Happymodel CrazyF411 AIO F4 2-4S Flight Controller w/ Frsky Receiver & Built-in 20A BL_S ESC for RC FPV Racing Drone Toothpick   Specification:   Brand Name: Happymodel   Model: CrazyF411 AIO   Item Name: F4 Flight Controller Built-in 20A BL_S ESC & Frsky Receiver      F4 Flight Controller   MCU:STM32F411CEU6 (100MHZ, 512K FLASH) Sensor: MPU-6000(SPI connection) Board size: 28.5 * 28.5MM Power supply: 2-4S battery input (DC 8V-17V) Built-in 20A(each) Blheli_S 4in1 ESC Dshot600 ready Built-in Frsky D8/D16 SPI receiverBuilt-in 2.4G Power Amplification Built-in Betaflight OSD(SPI Control) Built-in Current meter Built-in 5V 1.5A BEC Built-in voltage detection Firmware target: MATEKF411RX Yaw Degrees should set to “-90 degree” to match the flight direction      Onboard 20A ESC   MCU upgraded to EFM8BB21 Power supply: 2-4S LiPo/LiPo HV (7v/17v) Current: 20A continuous peak 25A (5 seconds) Support BLHeliSuite programmable Factory firmware: F_H_40_REV16_7.HEX Default protocol: DSHOT600      Internal Frsky NON-EU receiver Version   SPI BUS receiver Frsky D8/D16 compatibleCompatible Non EU transmitter both D8 mode and D16 mode Channels: 8ch/16chDual antenna Failsafe support No ground interference ( Transmitter and receiver 1 m from the ground): 400m      Features:   25.5x25.5mm Flight Controller AIO ESC board for toothpick .   Most powerful for whoop / toothpick style flight   Supports 2-4s battery input and provides 20A to the motors.   Also Integrated SPI Frsky receiver working with D8/D16 protocols.   This integrated receiver has PA/LNA power amplifier and the diversity antenna.   This should give more control range for this flight controller.      Bind procedure:   Make the on board receiver get into bind mode: For 4.0.x version firmware Plug USB and then connect betaflight configurator and then move to CLI tab , type “bind_rx_spi” ,the Red LED on the top of the flight controller will getting to be solid , the onboard receiver is in bind mode; For 4.1.x or 4.2.x the bind code is “bind_rx”      Make your transmitter get into bind mode . If bind is successful the red led will starting to blink. The red LED wouldn’t blinking when binding with some new ACCESS firmware frsky radio , but the bind is actual successful , need to go to CLI command and type “save” to finish the binding .      SPI Receiver option:   Frsky_D compatible with Frsky D8 protocol   Frsky_X compatible with Frsky non-eu D16 protocol   Frsky_X_LBT compatible with Frsky EU-LBT D16 protocol (4.0.