STM32F405 & AT32F435 Flight Controller for Betaflight firmware drones.

Yes, you can use any of those CPU with the same board. AT32 is more powerful and cheap but Betaflight support is in early stages.

The main idea of this project is to learn and play while designing a functional F4 Flight Controller compatible with Betaflight firmware.

Specs

• STM F405 or AT F435
• 6 UARTS
• MPU600 Gyro (also BMI and ICM)
• Blackbox, up to 128MB!
• 10v pad for DJI
• BMP280 Barometer
• OSD Support
• 3-6S voltage
• Buzzer pads
• SDA/SCL for GPS reconfiguring UART3

CURRENT STATUS (It works)

Version RC 1.1 is BEING TESTED.

• UART Inverter is disabled as the new RXs don't need it.
• Found wrong footprint size on the OSD capacitors.
  • They are too small for 47uF.
  • The 0402 pads are still ok for 0603 47uF.
  • Increased to 0603 in v.1.1.2
• AT32 chips hard to put into DFU mode.
  • Solved pulling dow BOOT1 pin (It was floating).
  • Ok for STM32.
  • Solved in v.1.1.2
• Reverse polarity protection circuit incomplete
  • R23 was not connected to ground.
  • Solved in v.1.1.2
• Upgraded 9v to 10v rails 

First test flight video

Already tested:

• Microprocesor
• Clock
• UARTS
• MPU600 Gyro
• 9/10v rail
• 5v rail
• 3.3v rail
• Flash memory
• Buzzer
• Baro chip
• OSD Chip

Pending to be tested:

• Alternative gyro to MPU6000

Known issues:

• UPDATE: On version 1.x 10v rails seems working fine with 4S and 6S lipo.

How to load betaflight

STM32F405 Chip

• Betaflight 4.5
  • Download Betaflight repo and compile the firmware for the next target file 
  • Acci FC - Target files (github.com)
• Betaflight < 4.5
  • Download Betaflight configurator 10.8 and flash the firmware version you prefer of the target STM32F405.
  • Once the firmware is loaded connect and enter cli to load the board configuration
  • Acci FC - Target files (github.com)

AT32F435 Chip

I have already succesfully build and run the design on a AT32F435 microcontroller with Betaflight 4.5. 

• Betaflight 4.5
  • Download Betaflight repo and compile the firmware for the next target file  
  • Acci FC - Target files (github.com)

All the targets can be found here: Acci FC - Target files (github.com)

Inspired in:

• https://oshwlab.com/Heinzeri/owl-f7-v1-fc (special thanks)
• https://oshwlab.com/mesh.drone/mesh-fc-v1-backup