What is a quadcopter flight controller?

The quadcopter flight controller is the brain of the quadcopter. The flight controller includes a processor, an array of sensors (a 3 axis gyroscope, a3 axis accelerometer and optionally a barometer, a magnetometer and a GPS), and takes the input from the receiver.

Using this input, the code running on the flight controller’s CPU works out how you want it to fly, and combines it with the sensor readings to calculate which rotors it should speed up and which rotors it should slowdown.

This way the flight controller translates your instructions into motor speed. Without a flight controller you’d have to drive the props directly from the receiver, so you’d have to assign a motor to a channel and use the sticks accordingly. For example the horizontal movements of the left stick could drive your front left motor, the vertical movements the front right, and so on.

While this could work with a large quadcopter for a short time, the first gust would blow you away because you just could not react fast enough. And besides it would not be much fun flying this way.

So the flight controller is there to help you, and it does this all hundreds or thousands time a second to keep your quad balanced.

Flight controllers consist of a software and a hardware part.

The hardware and software are only lousily coupled – you can run different flight controller software on the same hardware. For best results it’s good to match the two together.

The same hardware-software combination can support different kind of flying machines. Quadcopters, hexa- and octo-copters are usually supported, some flight controllers support tricopters and airplanes too.

The flight controller software comes with a computer based GUI tool too, which can help setting up and testing your quadcopter.

To choose a flight controller

you’ll have to decide how you’d like to fly. Flight controllers are specialized, and a flight controller tailored for autonomous GPS based flying would not perform well for FPVracing. The basic choices here are generic and FPV flying, aerial photography and finally autonomous, GPSbased flying.

For flight controller software

the most important is to get one that has all the features you need, and has a large enough community.

A controller software which only a few people use will not be well tested, and it will be hard to find solutions to your problems.

For simply flying around Cleanflight is probably the best choice today.

For flight controller hardware

choose one that’s wel lsupported by the software of your choice.

Besides this the two most important things to look out for in FC hardware are the processor and the gyro model, and the manufacturer’s rating. Flightcontrollers are complex and it’s easy to mess them up, so double check the number of FCs sold by the manufacturer, and the rating they got from the buyers.

In general the flight controller’s processor should have a high performance floating point unit, which is used for the in-flight calculations. If the floating point unit is slow or missing, a less precise integer based method will be used, which will result in a slightly worse flight performance. In the future more and more flight controller software will expect a high performance FPU.

Practically every flight controller on the market today uses¬†STMicroelectronics’ STM32 CPUs, the F1-F4 versions. The F4 is the newest and fastest, so go for this one if possible, otherwise choose an F3 based flight controllers. While the F1 based controllers are real ubiquitous workhorses, there isn’t much point in buying one nowadays.

The flight controllers gyro should be resilient both to electrical and mechanical noise,otherwise the quad will show hard-to-pin-down instabilities. TheMPU6500 is known to have issues, the MPU6050 seems to be OK.

Flight controllers for generic and FPV flying

The most popular flight controller software for this category are Cleanflight (a fork of Baseflight), Betaflight (a fork of Cleanflight for code cleanup), Raceflight (a fork of Cleanflight for better racing), and Librepilot (a fork of Openpilot due to internal issues). As Cleanflight is the most popular of the four, it is the safest choice.

For generic and FPV flying a wide range of hardware is available, forexample:

The Seriously Pro SPRacingF3, which is an STM32F3 based flight controller board. It supports the trio of Cleanflight, Betaflight and Raceflight. Buying this board will help support the development of Cleanflight. As the development of this board is closely tied to Cleanflight, this is the bes tcombination. The SPRacingF3 is available on Amazon and other online stores.

The Taulabs Sparky is another STM32F3 CPU based flight controller board which supports Cleanflight, Betaflight, Raceflight andTaulabs’ own flight controller software. This is a good choice too.

The X-Racer F303 is another good choice for Cleanflight, a sit’s one of the most popular boards for quads based on Oscar Liang’s¬†survey. The X-Racer sports an STM32F3series CPU, and supports Betaflight besides Cleanflight.Various versions of the X-Racer F303 are available online – go for the highest version number with the best reviews.

The Taulabs Sparky2 is an upgrade of the Sparky. TheSparky2 is a high-performance STM32F4 CPU based flight controller board,which supports Taulabs’ own software. As Betaflight and Raceflight support is underway it’s safer to revisit this board later. You can easily get the Sparky2online.

LibrePilot Revo also known as the OpenPilot Revolution is anew STM32F4 based board for LibrePilot. This is the best choice for LibrePilot. You can get a lot of versions from major online stores – make sure you double check the rating.

The OpenPilot CC3D is a very popular flight controller,based on the STM32F1 CPU series. This is a not a new model, but due to it’s sheer popularity it’s definitely worth mentioning. The CC3D supports Cleanflight, Librepilot, Betaflight and Raceflight. Choose this one if you want to go with a 110% proven, low-priced board.

The Naze32 is another old-school workhorse, based on theSTM32F1 series. This FC board supports the Cleanflight, Betaflight and Raceflight. The best Naze32 board to date is the Naze32 rev5, the rev6 is currently missing pass through mode for ESC configuration. You can get both the rev5 and the rev6 online.

Flight controllers for aerial photography

For aerial photography the best flight controllers are probably built by DJI. These flight controllers run DJI’s own software and have all you need to build a professional video or photography platform.

The DJI Naza M-Lite is the smallest of the two flight controllers. The highlight for aerial photography is the support for gimbal stablization – one less problem you have to solve with your quad. The Naza M-Lite also supports return to home on lost connection, has intelligent orientation support (this is a a GPS enhanced headlessmode). Besides quadcopters the Naza M-Lite also supports hexacopters.Choose this, except if you want to get the best of the best. You can get various versions of the Naza M-Lite online, including this great 450 size kit.

The DJI Naza M V2 supports everything the Naza M-Lite does,end even more: it comes with a free iPad-based ground station software,and supports octocopters too. A smartphone based assistant software can help with changing the settings out in the field via Bluetooth. With hexa- and octocopters the Naza can keep flying even if one of the motors have stopped- this can help to save the photography equipment and the quad itself. Just as the Naza M-Lite, the Naza M V2 is available on Amazon too.

Flight controllers autonomous flying

For autonomous GPS based flying, the two most popular flight controller software are Paparazzi and Ardupilot. Choose the Paparazzi if you want the largest possible feature set, even at the expense of a bit lacking GUI. Go with the Ardupilot if you’d prefer a bit more polished product.

The two best flight controller boards for autonomous flying

are probably the fully-featured Pixhawk for the Ardupilot, and the tiny but still powerful Elle0 for the Paparazzi.

The Pixhawk and it’s derivates are the best choice for the Ardupilot. These are high performance flight controllers, which sport a really wide range of hardware, including multiple gyros, magnetometers, accelerometers, and a barometer. There is a wide choice of attachable hardware too, including multiple GPS and GLONASS receivers, cameras etc… The Pixhawk is available from a wide range of online retailers, including Amazon.

The Elle0autopilot is an STM32F4 based board for Paparazzi. The Elle0 is equipped with a 3 axis gyro, accelerometer and magnetometer. It has a barometer too for altitude readings. The sensors are connected via a low-latency SPI bus, so performance should be better thanI2C using boards. The Elle0 is tiny, measuring only 30.5 x 30.5 millimeters,so it’s suitable for 250 and smaller sized drones too. The Elle0 is available in 1bitsquared’s online store.

For more information on flight controllers for GPS based flying check ou tthe flight controllers section in our “What is a GPS quadcopter?” article.

The quadcopter flight controller is the brain of the quadcopter. The flight controller includes a processor, an array of sensors (a 3 axis gyroscope, a3 axis accelerometer and optionally a barometer, a magnetometer and a GPS), and takes the input from the receiver.

Using this input, the code running on the flight controller’s CPU works out how you want it to fly, and combines it with the sensor readings to calculate which rotors it should speed up and which rotors it should slowdown.

This way the flight controller translates your instructions into motor speed. Without a flight controller you’d have to drive the props directly from the receiver, so you’d have to assign a motor to a channel and use the sticks accordingly. For example the horizontal movements of the left stick could drive your front left motor, the vertical movements the front right, and so on.

While this could work with a large quadcopter for a short time, the first gust would blow you away because you just could not react fast enough. And besides it would not be much fun flying this way.

So the flight controller is there to help you, and it does this all hundreds or thousands time a second to keep your quad balanced.

Flight controllers consist of a software and a hardware part.

The hardware and software are only lousily coupled – you can run different flight controller software on the same hardware. For best results it’s good to match the two together.

The same hardware-software combination can support different kind of flying machines. Quadcopters, hexa- and octo-copters are usually supported, some flight controllers support tricopters and airplanes too.

The flight controller software comes with a computer based GUI tool too, which can help setting up and testing your quadcopter.

To choose a flight controller

you’ll have to decide how you’d like to fly. Flight controllers are specialized, and a flight controller tailored for autonomous GPS based flying would not perform well for FPV racing. The basic choices here are generic and FPV flying, aerial photography and finally autonomous, GPSbased flying.

For flight controller software

the most important is to get one that has all the features you need, and has a large enough community.

A controller software which only a few people use will not be well tested, and it will be hard to find solutions to your problems.

For simply flying around Cleanflight is probably the best choice today.

For flight controller hardware

choose one that’s well supported by the software of your choice.

Besides this the two most important things to look out for in FC hardware are the processor and the gyro model, and the manufacturer’s rating. Flight controllers are complex and it’s easy to mess them up, so double check the number of FCs sold by the manufacturer, and the rating they got from the buyers.

In general the flight controller’s processor should have a high performance floating point unit, which is used for the in-flight calculations. If the floating point unit is slow or missing, a less precise integer based method will be used, which will result in a slightly worse flight performance. In the future more and more flight controller software will expect a high performance FPU.

Practically every flight controller on the market today uses STMicroelectronics’ STM32 CPUs, the F1-F4 versions. The F4 is the newest and fastest, so go for this one if possible, otherwise choose an F3 based flight controllers. While the F1 based controllers are real ubiquitous workhorses, there isn’t much point in buying one nowadays.

The flight controllers gyro should be resilient both to electrical and mechanical noise,otherwise the quad will show hard-to-pin-down instabilities. TheMPU6500 is known to have issues, the MPU6050 seems to be OK.

Flight controllers for generic and FPV flying

The most popular flight controller software for this category are Cleanflight (a fork of Baseflight), Betaflight (a fork of Cleanflight for code cleanup), Raceflight (a fork of Cleanflight for better racing), and Librepilot (a fork of Openpilot due to internal issues). As Cleanflight is the most popular of the four, it is the safest choice.

For generic and FPV flying a wide range of hardware is available, for example:

The Seriously Pro SPRacingF3, which is an STM32F3 based flight controller board. It supports the trio of Cleanflight, Betaflight and Raceflight.Buying this board will help support the development of Cleanflight. As the development of this board is closely tied to Cleanflight, this is the best combination. The SPRacingF3 is available on Amazon and other online stores.

The Taulabs Sparky is another STM32F3 CPU based flight controller board which supports Cleanflight, Betaflight, Raceflight andTaulabs’ own flight controller software. This is a good choice too.

The X-Racer F303 is another good choice for Cleanflight, as it’s one of the most popular boards for quads based on Oscar Liang’s¬†survey. The X-Racer sports an STM32F3series CPU, and supports Betaflight besides Cleanflight.Various versions of the X-Racer F303 are available online – go for the highest version number with the best reviews.

The Taulabs Sparky2 is an upgrade of the Sparky. TheSparky2 is a high-performance STM32F4 CPU based flight controller board,which supports Taulabs’ own software. As Betaflight and Raceflight support is underway it’s safer to revisit this board later. You can easily get the Sparky2online.

LibrePilot Revo also known as the OpenPilot Revolution is anew STM32F4 based board for LibrePilot. This is the best choice for LibrePilot. You can get a lot of versions from major online stores – make sure you double check the rating.

The OpenPilot CC3D is a very popular flight controller,based on the STM32F1 CPU series. This is a not a new model, but due to it’s sheer popularity it’s definitely worth mentioning. The CC3D supports Cleanflight, Librepilot, Betaflight and Raceflight. Choose this one if you want to go with a 110% proven, low-priced board.

The Naze32 is another old-school workhorse, based on theSTM32F1 series. This FC board supports the Cleanflight, Betaflight and Raceflight. The best Naze32 board to date is the Naze32 rev5, the rev6 is currently missing pass through mode for ESC configuration. You can get both the rev5 and the rev6 online.

Flight controllers for aerial photography

For aerial photography the best flight controllers are probably built by DJI. These flight controllers run DJI’s own software and have all you need to build a professional video or photography platform.

The DJI Naza M-Lite is the smallest of the two flight controllers. The highlight for aerial photography is the support for gimbal stablization – one less problem you have to solve with your quad. The Naza M-Lite also supports return to home on lost connection, has intelligent orientation support (this is a a GPS enhanced headless mode). Besides quadcopters the Naza M-Lite also supports hexacopters.Choose this, except if you want to get the best of the best. You can get various versions of the Naza M-Lite online, including this great 450 size kit.

The DJI Naza M V2 supports everything the Naza M-Lite does,end even more: it comes with a free iPad-based ground station software,and supports octocopters too. A smartphone based assistant software can help with changing the settings out in the field via Bluetooth. With hexa- and octocopters the Naza can keep flying even if one of the motors have stopped- this can help to save the photography equipment and the quad itself. Just as the Naza M-Lite, the Naza M V2 is available on Amazon too.

Flight controllers autonomous flying

For autonomous GPS based flying, the two most popular flight controller software are Paparazzi and Ardupilot. Choose the Paparazzi if you want the largest possible feature set, even at the expense of a bit lacking GUI. Go with the Ardupilot if you’d prefer a bit more polished product.

The two best flight controller boards for autonomous flying

are probably the fully-featured Pixhawk for the Ardupilot, and the tiny but still powerful Elle0 for the Paparazzi.

The Pixhawk and it’s derivates are the best choice for the Ardupilot. These are high performance flight controllers, which sport a really wide range of hardware, including multiple gyros, magnetometers, accelerometers,and a barometer. There is a wide choice of attachable hardware too,including multiple GPS and GLONASS receivers, cameras etc… The Pixhawk isavailable from a wide range of online retailers, including Amazon.

The Elle0autopilot is an STM32F4 based board for Paparazzi. The Elle0 is equipped with a 3 axis gyro, accelerometer and magnetometer. It has a barometer too for altitude readings. The sensors are connected via a low-latency SPI bus, so performance should be better thanI2C using boards. The Elle0 is tiny, measuring only 30.5 x 30.5 millimeters,so it’s suitable for 250 and smaller sized drones too. The Elle0 is available in 1bitsquared’s online store.

For more information on flight controllers for GPS based flying check out the flight controllers section in our “What is a GPS quadcopter?” article.

Have fun flying!

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