What is a RC Flight Controller


So, you’ve taken the plunge into the world of FPV drones. You’ve experienced the thrill of soaring through the sky, capturing breath-taking aerial footage, and mastering jaw-dropping manoeuvres. But have you ever stopped to wonder what makes your drone fly so smoothly and precisely? The answer lies in the flight controller, the unsung hero of every FPV drone. In this comprehensive guide, we’ll take a deep dive into the world of flight controllers. From understanding their inner workings to choosing the right one for your needs, we’ve got you covered. So, fasten your seatbelts and get ready to unlock the full potential of your FPV drone!

Understanding the Flight Controller: The Brain Behind Your Drone

Diy Multiwii flight controller
pixhawk flight controller

At its core, a flight controller (FC) is like the brain of your FPV drone. It’s a small circuit board packed with sensors that detect your drone’s movements and user commands. Armed with this information, the flight controller adjusts the speed of the motors to move your drone in the desired direction. But that’s not all – flight controllers can also act as a hub for other drone peripherals, such as ESCs, GPS units, LED lights, servos, radio receivers, FPV cameras, and video transmitters (VTX). As technology advances, flight controllers are becoming smaller, more feature-packed, and equipped with better processors and hardware. Let’s explore the various aspects of flight controllers that make them the cornerstone of every FPV drone.

The Inner Workings of a Flight Controller

A flight controller is equipped with a variety of sensors that enable it to gather crucial data about your drone’s orientation, position, and movement. The most fundamental sensors found in all flight controllers are gyroscopes (gyros) and accelerometers (accs). Gyroscopes measure the angular velocity of your drone, while accelerometers measure its linear acceleration. By combining data from these sensors, the flight controller can precisely determine your drone’s attitude and make real-time adjustments to keep it stable and responsive.

To enhance the capabilities of your flight controller, some models come with additional sensors like barometric pressure sensors (barometers) and compasses (magnetometers). Barometers enable your drone to measure changes in altitude, while compasses help it maintain a steady heading. These extra sensors open up a whole new world of possibilities, from automated flying modes to GPS waypoint missions.

Choosing the Right Flight Controller for Your Needs

The market is flooded with a wide range of flight controllers, each offering its own set of features and capabilities. But how do you choose the right one for your needs? Here are some key factors to consider:

1. Processor Power: Unlocking High-Speed Performance

The processor is the heart and soul of your flight controller, responsible for executing complex calculations and running the firmware that controls your drone. Flight controllers use microcontroller units (MCUs) to store firmware codes and perform these calculations. Different flight controllers utilize different MCUs, each with its own calculation speed and memory size. The most common MCUs used in flight controllers are F4, F7, and H7, with each subsequent model boasting faster speeds and larger memory capacities. When choosing a flight controller, consider the demands of your flying style and the features you plan to use. If you’re a seasoned pilot who loves pushing the limits of performance, opt for a flight controller with a beefier processor.

2. Firmware Options: Unleashing the Full Potential

Beyond hardware considerations, flight controllers also offer a variety of firmware options. Firmware is the software that runs on your flight controller and determines its behaviour and feature set. Different firmware options cater to different applications and personal preferences. Here are some popular firmware choices:

When choosing a firmware, consider your flying goals, preferred features, and the level of customization you desire. Experimenting with different firmware options can be an exciting way to unlock new possibilities and tailor your drone to your specific needs.

3. Configuration and Tuning: Fine-Tuning Your Flying Experience

Once you’ve chosen your flight controller and firmware, it’s time to dive into the world of configuration and tuning. Configuring your flight controller involves adjusting various settings to optimize its performance and tailor it to your flying style. Each firmware has its own user interface (UI) and parameters that can be tweaked. While the overall process may vary slightly depending on the firmware, the general principle remains the same. You’ll be adjusting settings like PID (Proportional-Integral-Derivative) values, RC rates, and filters to achieve the desired flight characteristics. Tuning your drone is a trial-and-error process that requires patience and experimentation. It’s all about finding the sweet spot where your drone feels locked-in, responsive, and perfectly suited to your piloting style. Don’t be afraid to dive in and make adjustments – it’s all part of the FPV journey!

Exploring the Anatomy of a Flight Controller

To fully understand the capabilities of a flight controller, let’s take a closer look at its key components and features.

1. UART: The Communication Lifeline

UART, or Universal Asynchronous Receiver/Transmitter, is a hardware serial interface that allows external devices to connect to the flight controller. UART ports serve as communication channels for devices like radio receivers, telemetry modules, GPS units, and more. Each UART port consists of two pins – one for transmitting data (TX) and one for receiving data (RX). It’s important to note that the TX pin on the device connects to the RX pin on the flight controller, and vice versa. UART ports play a crucial role in expanding the capabilities of your FPV drone and enabling seamless integration with various peripherals.

2. UART Inversion: Overcoming Compatibility Challenges

If you’re using Frsky receivers, you may encounter the issue of UART inversion. Frsky receivers output inverted signals, which means they require special handling to be correctly interpreted by the flight controller. While some flight controllers, like those equipped with F3, F7, or H7 MCUs, can handle inverted signals without any additional hardware, others, such as those with F1 or F4 MCUs, require an external inverter. To work around this, some F4 flight controllers have dedicated pads for SBUS connections, or you can utilize alternative methods to obtain the un-inverted signal from the receiver. It’s crucial to ensure UART compatibility when setting up your FPV drone, especially if you’re using Frsky receivers.

3. Gyroscope: Keeping Your Drone Stable and Responsive

The gyroscope, or gyro for short, is a crucial sensor in the flight controller that measures your drone’s angular velocity. It detects changes in orientation and helps the flight controller keep your drone stable and responsive. When combined with the accelerometer, which measures linear acceleration, the gyroscope forms the foundation for flight stabilization and control. There are several types of gyros available, each with its own communication protocols and maximum effective sampling frequencies. The most common gyro models include MPU6000, MPU6050, MPU6500, ICM20602, and BMI270. Choosing the right gyro for your flight controller depends on factors such as sampling rate, noise resistance, and compatibility with your chosen firmware.

4. Layout: The Key to Seamless Integration

Flight controller layout refers to the arrangement of pins and solder pads on the board. While it may seem like a minor detail, the layout plays a crucial role in the ease of connecting various components to your flight controller. A well-designed layout can make the wiring process a breeze, while a poorly laid-out board can lead to frustrating cable management and potential compatibility issues. When choosing a flight controller, pay attention to its layout and ensure that it aligns with your build requirements. Look for flight controllers with clearly labelled and grouped pads, allowing for easy and intuitive connections.

5. ESC Compatibility: Ensuring a Smooth Connection

ESCs, or Electronic Speed Controllers, are responsible for regulating the speed of your drone’s motors. When choosing a flight controller, it’s essential to consider its compatibility with your ESCs. Many FPV drones today use 4-in-1 ESCs, which are sold as a stack alongside the flight controller. These pre-integrated stacks offer a plug-and-play solution, ensuring seamless compatibility. However, if you’re using ESCs and flight controllers from different brands, check their compatibility and ensure that the necessary connections and plugs match. Mismatched connections can lead to compatibility issues and potential damage to your flight controller.

6. Mounting Pattern: Finding the Perfect Fit

The mounting pattern refers to the distance between adjacent mounting holes on a flight controller. It determines the compatibility of the flight controller with your drone frame. Common mounting patterns include 30.5×30.5mm, 25.5×25.5mm, 20×20mm, and 16×16mm. Larger drones typically use the 30.5×30.5mm pattern, while smaller drones opt for the 25.5×25.5mm or 20×20mm patterns. Micro builds under 100mm often utilize the compact 16×16mm pattern. When selecting a flight controller, ensure that its mounting pattern matches your drone frame to ensure a secure and stable fit.

7. Blackbox: Unlocking the Power of Data

Blackbox is a powerful tool that allows you to record and analyse flight data from your drone. It’s invaluable for tuning and troubleshooting, enabling you to fine-tune your drone’s performance and diagnose issues with precision. There are two primary methods of recording flight data: using integrated flash memory or storing it on an SD card if your flight controller has an onboard SD card logger. Flash memory is a cost-effective solution but offers limited storage capacity. On the other hand, using an SD card allows you to record data continuously without worrying about storage limitations. Blackbox logs provide valuable insights into your drone’s performance, allowing you to maximize its potential and capture the perfect flight.

8. BEC: Powering Your Drone’s Peripherals

BEC, or Battery Eliminator Circuit, is a voltage regulator found on most flight controllers. Its primary function is to provide a stable power source for your drone’s peripherals, such as the radio receiver, GPS module, and FPV camera. While you can power these devices directly from the drone’s battery, using a regulated power source like the BEC can lead to better performance and reduced electrical noise. When choosing a flight controller, consider the voltage and current requirements of your peripherals and ensure that the BEC meets their specifications. A reliable and properly configured BEC can make a significant difference in the overall performance of your FPV drone.

9. Barometer: Enhancing Altitude Precision

Some flight controllers come equipped with a barometric pressure sensor, also known as a barometer. This sensor allows your drone to measure changes in altitude with high precision. Barometers enable advanced features like altitude hold and can enhance the accuracy of GPS-assisted flight modes. While not mandatory for every FPV drone, a barometer can be a valuable addition if you plan on flying in environments where altitude precision is critical.

10. OSD Chip: Adding a Personal Touch to Your FPV Experience

For analogue FPV systems, flight controllers often come equipped with an On-Screen Display (OSD) chip. The OSD chip overlays critical flight data, such as battery voltage, flight time, and RSSI (Received Signal Strength Indication), onto your FPV feed. This information allows you to monitor your drone’s vital parameters in real-time, without the need for additional external OSD modules. OSD chips enhance the overall FPV experience, providing crucial information at a glance. For digital FPV systems, such as DJI, HDZero, and Avatar, OSD functionality is typically achieved through a spare UART port, eliminating the need for an OSD chip.

The Evolution of Flight Controllers

The world of flight controllers has come a long way since the early days of FPV drones. Let’s take a brief journey through their evolution to appreciate the advancements that have shaped the FPV landscape.

In 2009, a passionate maker combined the Wii Motion Plus accessory with an Arduino board to control a drone. This sparked the development of the Multiwii project, which eventually led to the creation of the first dedicated flight controller board. The Multiwii flight controller, powered by an 8-bit Atmel processor, laid the foundation for future innovations.

In 2013, a developer named “timecop” took the Multiwii project to new heights. He created the Naze32 flight controller, utilizing a powerful ARM 32-bit processor. This marked the birth of the Baseflight firmware, a modified version of Multiwii. The Naze32 flight controller popularized the 35x35mm form factor, with 30x30mm mounting, which is still widely used today.

In 2014, another developer named “Hydra” built upon the work of Baseflight and created Cleanflight. Cleanflight introduced significant improvements and optimizations, pushing the boundaries of flight controller performance. Meanwhile, the flight controller market exploded with manufacturers developing their own variants, each offering unique features and capabilities.

In 2015, BorisB, a talented developer, took Cleanflight’s source code and embarked on a mission to create a firmware that would redefine the FPV experience. The result was Betaflight, a firmware that focused on performance enhancements, new features, and customization options. Betaflight quickly gained popularity and established itself as the go-to firmware for FPV drones. Today, Betaflight continues to evolve, with frequent updates and a vibrant community driving its development.


The flight controller is the beating heart of every FPV drone. It’s the brain that keeps your drone stable, responsive, and capable of mind-blowing manoeuvres. Choosing the right flight controller and firmware can unlock new possibilities and elevate your flying experience to new heights. From processors and firmware options to configuration and tuning, every aspect of the flight controller plays a crucial role in shaping your FPV journey. So, embrace the power of the flight controller, experiment with different setups, and let your creativity soar. With the right flight controller by your side, the sky’s the limit!

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