Custom fc rat

Custom Flight Controller PCB

A custom-designed flight controller PCB developed for embedded flight-control applications, integrating a high-performance STM32 MCU, multiple inertial and pressure sensors, CAN communication, external flash memory, power management, and dedicated FMU/IO interfaces.

The PCB and schematic were designed using KiCad 9.0.7.

📌 Project Overview

This project focuses on the design and development of a custom flight controller PCB with dedicated interfaces for sensors, communication peripherals, power, debugging, telemetry, PWM outputs, and RC input/output.

The design is divided into multiple functional sections:

• Main Flight Management Unit (FMU)
• IO controller
• IMU and pressure sensing
• CAN communication
• USB connectivity
• External SPI flash memory
• Power regulation
• Telemetry interfaces
• PWM and RC interfaces
• Debug/programming interfaces

✨ Key Features

• Custom PCB designed from schematic to board layout
• STM32F765VITx main flight controller MCU
• STM32F103CBTx dedicated IO controller
• Multiple onboard sensors
• CAN communication interface
• USB OTG interface
• External SPI flash memory
• Multiple UART interfaces
• I2C and SPI interfaces
• PWM output interface
• SBUS and PPM interfaces
• Debug/programming interface
• Dedicated GPS and telemetry connectors
• Onboard status/safety LEDs
• 3.3 V and 5 V power domains
• Multi-layer PCB layout
• Manufacturing-ready Gerber and drill files

🧠 Hardware Architecture

Main Flight Controller

The primary processing unit is an STM32F765VITx.

The MCU provides the main processing and peripheral interfaces for the flight-control system, including:

• SPI
• I2C
• UART
• CAN
• Timer/PWM channels
• SWD debugging
• External GPIO

IO Controller

A dedicated STM32F103CBTx is used for the IO section of the design.

The IO controller provides interfaces for:

• SBUS
• PPM
• PWM
• RC input/output
• Safety signals
• Status LEDs
• Debugging
• Additional UART interfaces

📡 Sensors

The design incorporates multiple sensors:

ICM-42688-P

6-axis inertial measurement sensor connected through SPI.

BMI270

6-axis inertial sensor with dedicated interrupt and SPI connections.

ICP-20100

Pressure sensor connected through the I2C interface.

BMM150

Magnetic sensor connected through the I2C interface.

🔌 Communication Interfaces

CAN

CAN communication is implemented using the SN65HVD230 transceiver with dedicated CANH and CANL connections and protection circuitry.

USB

A USB OTG interface is provided along with USB ESD protection using USBLC6-2P6.

UART / Telemetry

Dedicated connectors are provided for:

• TELEM1
• TELEM2
• TELEM3
• UART/I2C interface
• GPS
• FMU communication

I2C

Multiple I2C buses are available for sensor and peripheral communication.

SPI

Multiple SPI buses are routed to sensors, flash memory, and external interfaces.

💾 External Flash Memory

The board includes external SPI flash memory:

W25Q128JVS

The flash device is connected to the main MCU through SPI with a dedicated chip-select signal.

⚡ Power Management

The PCB contains dedicated power regulation and filtering circuitry for the different system power domains.

The design includes:

• 5 V input
• 3.3 V regulation
• USB 5 V input
• External 3.3 V supply
• Decoupling capacitors
• Ferrite filtering
• Power indication circuitry

The schematic includes regulators such as:

• LM1117DT-3.3
• TLV75733PDBVR

🎛️ Interfaces & Connectors

🖥️ PCB Design

3D View – Top

3D View – Bottom

PCB Layout

📐 Schematic

The complete schematic is provided as a multi-page KiCad schematic covering:

1. FMU / MCU power and peripherals
2. USB and CAN
3. IMU and sensor interfaces
4. IO controller
5. Safety, RC and PWM interfaces

The PDF version is available in:

docs/schematic.pdf

🏭 Manufacturing Files

The gerbers/ directory contains the manufacturing outputs generated from KiCad, including:

• Front and back copper
• Inner copper layers
• Front and back solder mask
• Front and back silkscreen
• Paste layers
• Board outline
• Drill files
• Gerber job file

These files can be supplied to a PCB manufacturer for fabrication.

📦 Bill of Materials

A Bill of Materials generated from the KiCad schematic is included in:

manufacturing/BOM.csv

The BOM contains information such as:

• Reference designators
• Component quantity
• Component value
• PCB footprint
• Datasheet information
• BOM exclusion fields

📁 Repository Structure

Custom-FC-RAT/
│
├── README.md
├── custom_fc_rat.kicad_pro
│
├── schematic/
│   └── custom_fc_rat.kicad_sch
│
├── pcb/
│   └── custom_fc_rat.kicad_pcb
│
├── gerbers/
│   ├── *.gbl
│   ├── *.gtl
│   ├── *.gbs
│   ├── *.gts
│   ├── *.gbo
│   ├── *.gto
│   ├── *.gm1
│   ├── *.g1
│   ├── *.g2
│   ├── *.g3
│   ├── *.g4
│   ├── *.drl

🛠️ Design Tools

🚀 Future Improvements

Possible future development includes:

• Hardware validation and bring-up documentation
• Flight-controller firmware integration
• Sensor calibration and validation
• Power integrity testing
• Communication interface testing
• EMI/EMC validation
• Flight testing
• PCB revisions based on hardware testing

📄 Documentation

The editable KiCad design files and schematic PDF are included so that the hardware design can be inspected and further developed.

👩‍💻 Author

Ekta Gupta

Custom PCB / Flight Controller Design Project

⭐ Project Status

Hardware Design Completed

Schematic, PCB layout, 3D visualization, BOM, and manufacturing files are included in this repository.