Holybro Kakute F4 Mini

../_images/holybro-kakutef4-mini.jpg

above image and some content courtesy of Holybro

Specifications

  • Processor
    • STM32F405RGT6 32-bit processor
    • MAX7456 OSD chip
  • Sensors
    • MPU6000 IMU (accel, gyro)
    • BMP280 barometer
  • Power
    • 7V ~ 42V input power directly from battery
  • Interfaces
    • 5x PWM outputs
    • 1x RC input PWM/PPM
    • 5x UARTs/serial for GPS and other peripherals
    • 1x I2C port for external compass
    • micro USB port
    • Camera and Video TX
  • Logging
    • 128Mb flash for logging

Where to Buy

Pinout

../_images/kakutef4-mini-pinout.png

UART Mapping

The UARTs are marked Rn and Tn in the above pinouts. The Rn pin is the receive pin for UARTn. The Tn pin is the transmit pin for UARTn.

The pin labeled Rx on each corner of the board is a common pin for ESC telemetry input.

  • SERIAL0 -> USB
  • SERIAL1 -> USART1 (TX only for Frsky Telem, no ext inverter needed)
  • SERIAL3 -> USART3 (RC Input protocols by default. PPM not supported)
  • SERIAL4 -> UART4 (GPS/Telem1)
  • SERIAL5 -> UART5 (RX only, ESC Telemetry protocol by default)
  • SERIAL6 -> USART6 (GPS2/Telem2)

RC Input

RC input is configured on the R6 (UART3_RX) pin. It supports all RC protocols except PPM.

ESC Telemetry

The SERIAL5 port (UART5) is for ESC telemetry. It is connected through the motor connector and works out of the box with the Tekko32 F3 Mini which is commonly paired with this flight controller.

FrSky Telemetry

FrSky Telemetry is supported using the SmartPort pad (UART1). You need to set the following parameters to enable support for FrSky S.PORT. It has built-in inverters and a diode to allow for operation from a single pin with no special adapters.

OSD Support

The KakuteF4 supports OSD using OSD_TYPE 1 (MAX7456 driver).

PWM Output

The KakuteF4 supports up to 5 PWM outputs. The pads for motor output M1 to M5 on the above diagram are for the 5 outputs. M1-4 outputs support DShot and Bi-Directional DShot, as well as all PWM types. The M5 is defaulted to support serial LEDs instead of PWM but can be changed by changing its default function using SERVO5_FUNCTION.

The PWM is in 2 groups:

  • PWM 1 and 2 in group 1
  • PWM 3 and 4 in group 2
  • PWM 5 in group 3

Channels within the same group need to use the same output rate, whether PWM or Dshot. If any channel in a group uses DShot then all channels in the group need to use DShot.

Battery Monitoring

The board has a built-in voltage and current sensor. The voltage sensor can handle up to 6S LiPo batteries.

The correct battery setting parameters are:

Compass

The KakuteF4 Mini does not have a built-in compass, but you can attach an external compass using I2C on the SDA and SCL pads.

Logging

The KakuteF4 supports on-board data flash logging. Use LOG_BACKEND_TYPE = 2)

Loading ArduPilot onto the board

Initial firmware load can be done with DFU by plugging in USB with the bootloader button pressed. Then you should load the “with_bl.hex” firmware, using your favourite DFU loading tool. See Loading Firmware onto boards without existing ArduPilot firmware

Once the initial firmware is loaded you can update the firmware using any ArduPilot ground station software. Updates should be done with the KakuteF4Mini firmware files. See Loading Firmware.