AZB-12 AN-08 · karatefc.notazizelse.xyz

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Application note AN-08 · U8

KarateFC

2026 · karatefc.notazizelse.xyz
ABSTRACT

My next flight controller, in the class of the SpeedyBee F405 V3: STM32F405, USB-C, Betaflight-compatible. It's for fast research drones that get destroyed on purpose at the end of each test.

That changes the whole design. Normal FPV boards are built to survive a crash and get repaired. Here the board dies anyway, so what matters is cost per unit, how fast I can build a batch, and that it stays reliable right up until impact.

Concept sketch of a 36 mm flight controller with an STM32F405 and a 30.5 mm hole pattern
Figure 1.Concept sketch: STM32F405, USB-C, 30.5 mm mounting. Not a real layout yet.

1Key Specifications

MCU
STM32F405
Firmware
Betaflight-compatible
For
Fast, single-use research drones
Tools
KiCad 10
Funding
Hack Club Forge (planned)
Started
22 September 2026

2Functional Block Diagram

  1. configUSB-C
  2. brainSTM32F405
  3. firmwareBetaflight
  4. powerESCs
  5. output4 motors
Figure 2.How KarateFC works, left to right

3First decision

A separate 4-in-1 ESC stack, or the ESCs on the flight controller (AIO)? For drones that get thrown away, fewer boards and fewer connectors usually wins. At Unique Dynamic I wrote a flight controller's firmware from zero. This time I'm using Betaflight so the effort goes into the hardware.

4Technical Documents

AN-08-D1Project planSpec, the design principle, the ESC decision, deadlines.Read →AN-08-D2ResourcesReference designs, datasheets and guides I'm using.Read →AN-08-D3JournalRead →

5Source