Introduction: A flight controller with a builtin Serial ELRS receiver and 4IN1 BL_S 12A ESC specially developed for Digital HD FPV, which removes the analog OSD chip 7456, optimizes the PCB layout, and supports 1-2S Lipo / LiHV lithium batteries, very Suitable for Digital HD Tinywhoop / Cinewhoop / Toothpick and other small FPV drones. The flight controller uses the F405 chip, supports Betaflight/INAV firmware, has 3 sets of complete UARTs available, and integrates a BMP280 barometer and 8Mbp blackbox, which greatly enhances the playability of the flight controller. Specification: Brand: Happymodel Model: CrazyF405HD Item Name: F4 Flight Controller AIO 12A 4in1 ESC ELRS Receiver Mount size: 25.5x25.5mm Weight: 4.8g (without power lead wire) Flight ControllerMCU: STM32F405RGT6 (168MHZ, 1Mbyte FLASH) GYRO Sensor: BMI270 (SPI connection) Mount hole size: 25.5mm*25.5mm Power supply: 1-2S battery input (DC 2.9V-8.7V) Built-in 12A(each) Blheli_S 4in1 ESC Built-in Serial ExpressLRS 2.4G Built-in BMP280 Barometer Built-in 8MBp blackbox Built-in voltage meter sensor , voltage meter scale 110 Built-in current meter sensor , current meter scale 470 Onboard 4in1 ESC Power supply: 1-2S LiPo/LiPo HV Current: 12A continuous peak 15A (3 seconds) Support BLHeli_S Bluejay firmware Factory firmware: Bluejay ESC V0.19 Firmware target: Z-H-30 Default protocol: DSHOT300 When use 1s battery and high KV 0702/0802 motors, should set startup power to 1100/1200 Onboard UART ExpressLRS 2.4GHz Receiver Packet Rate option: 25Hz/50Hz/150Hz/250Hz/500Hz RF Frequency: 2.4GHz Antenna: enameled copper wire 31mm length Telemetry output Power: