Name: f4 nano flight controller size: 27*27mm • mounting holes: 20*20mm firmware version: omnibusf4sd • bec: 5v@1a • bb+, bb-: pins for connecting the “positive/+” & “negative/-” of the external buzzer. Led-strip: the fc outputs “control signals” to control the ws2812b led strip. (note: for the fcs with firmware from version 3. 17, you need to key in “resource led_strip a8” first and then save on the cli of the betaflight software and then press the “enter” button on the keyboard if you want to use the led function. ) vbat+: battery voltage output port. • video-in/out: video input/output port of the onboard osd microchip stm32 f405 mcu allows the fc to run the pid looptime and gyro with higher frequency. Spi sensor mpu6000 includes an accelerometer and a gyro. Onboard osd microchip which supports the dma mode allows users to adjust its parameters via the betaflight software. (note: the osd is controlled by the f4 mcu. ) the fc which supports betaflight firmware & allows parameter adjustment via betaflight software is more applicable to fpv race. Tf-card which can record and save more flight/black box data allows users to adjust the setup of their aircraft easily. Compatible with various receivers like sbus, sumh, sumd, spektrum1024/2048, xbus, ppm and etc. Led strip signal output port allows users to adjust the color & flash mode of the led strip via the fc. Volt/amp monitoring port allows users to check the battery voltage ( vbat+ port ) and current ( crt port ) (extra current meter is needed). Buzzer output port allows users to connect external buzzer(s) to the fc for warning or informing the flight status of the aircraft. Micro usb port allows users to connect the fc to a pc to flash firmware and adjust parameters. (hw31001001)