SpeedyBee F405 Mini BLS 35A 20×20 Stack

The SpeedyBee F405 Mini BLS 35A 20x20 Stack pairs an STM32F405 flight controller with a 35A BLHeli_S 4-in-1 ESC. Engineered with a compact 20x20mm mounting footprint, this stack is specifically built for 2-inch to 4-inch sub-250g quadcopters, lightweight 5-inch toothpick builds, and cinewhoop frames running on 3S to 6S LiPo power.

Key features

• Wireless configuration: Built-in Bluetooth connectivity allows flight controller and ESC parameter configuration directly from your smartphone using the SpeedyBee mobile app (iOS and Android); firmware flashing and Blackbox analysis still need a PC.

• HD and analog compatibility: Connects to the DJI O3 Air Unit, RunCam Link, Caddx Vista and DJI Air Unit V1 by soldering directly to dedicated pads (9V, G, T1, R1, G, SBUS), alongside standard solder pads for analog video transmitters.

• Dual BEC power outputs: Integrated voltage regulators deliver a steady 5V/2A for receivers, GPS, and LEDs, plus a dedicated 9V/3A rail to cleanly power high-definition VTX modules.

• 35A 4-in-1 ESC: Delivers 35A continuous current per channel with a 45A 10-second burst rating. Runs on BLHeli_S firmware and supports BlueJay out of the box to enable bi-directional DShot and RPM filtering.

• Comprehensive hardware connectivity: Equipped with 6 full hardware UART sets, an I2C port for GPS/compass integration, a built-in barometer, and 8MB of onboard flash storage for Blackbox flight data logging.

Specifications

• MCU: STM32F405RGT6

• Gyro / IMU: ICM42688P

• Input Voltage: 3-6S LiPo

• ESC Continuous / Burst Current: 35A x 4 / 45A (10s)

• ESC Firmware: BLHeli_S (BlueJay compatible)

• BEC Outputs: 5V 2A, 9V 3A

• Extra outputs: 3.3V (500mA), 4.5V (1A, live on USB power for receiver and GPS)

• OSD: AT7456E

• Hardware UARTs: 6

• Blackbox Storage: 8MB Onboard Flash

• Mounting Size: 20x20mm (M2 / M3 compatible via grommets)

• Dimensions: 32 x 35 x 14.2 mm

• Supported Firmware: Betaflight, INAV

• Total Stack Weight: 13.5g

This stack is ideal for builders seeking the advanced feature set of full-sized 30.5x30.5mm flight controllers—such as native Bluetooth app tuning and direct HD VTX wiring—condensed into a space-saving 20x20mm form factor.