F405 HD ELRS AI0 flight controller with for integrated UART 2.4 GHz Express SLRS receiver and 20A BIheli_s ESC (pre-installed firmware) can support 3-4 batteries Bigger Mosfet can support up to 20A, which be better for 3-4S Toothpick drones or long-range FPV drones. 6-pin socket is reserved for HD devices to plug and play. This is a great solution for building a high-definition digital FPV drone. Binding steps: 1. Power the flight controller via USB plug and unplug. When the red LED on the flight controller turns off, disconnect the power immediately and repeat the above steps again. When the FC is powered on for the third time, the red LED starts to flash twice, indicating that the onboard receiver has entered binding mode 2. Make sure your ExpressLRS tx high-frequency head module firmware is v3.x.x. Then go to ExpressLRS.lua from the "Tools" menu of the radio transmitter. Then click [Bind] to bind with the onboard ExpressLRS receiver. The red LED should flash slowly and then stay on, indicating that the binding is successful. If the red indicator flashes three times after binding, please change the value of the Model Matching tab from "Off" to "On" or from "On" to "Off" Receiver LED status meaning: The red LED is always on to indicate successful binding or RC link establishment; the red LED double flashes to indicate entering binding mode; the red LED flashes slowly to indicate that the TX module has no RC signal input; the red LED flashes and continuously to indicate that the ExpressLRS wifi is enabled; the red LED flashes three times to indicate that the model does not match and the model matching needs to be modified in ExpressLRS.lua Serial port description: The ELRS receiver is connected to UART2 by default when it leaves the factory. Usually UART1 is used for MSPOSD of high-definition image transmission such as DJl//HDZERO UART6 can be used for GPS or other serial devices. IRX6 is an inverted serial RX6 for SBUS input. IRX6 and /RX6 cannot be used at the same time. Due to different batches, there may be differences in product appearance, color, and printed text, which not affect the use. Color: As Shown Material: PCB+Plastic Package Contents: 1 * Flight Controller Kit Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.