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ESC protocols overview with implementation on STM32

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 What is ESC protocol? When our flight controller calculates new values for each of the motors they need to be sent to ESC microcontroller which can then process these values and control MOSFETs. How exactly signals are received and then send to motors is ESC's software secret, which is another really interesting and complicated topic. For now, let's know that we can not control the motors or even MOSFETs from our FC, we need to send new values between two microcontrollers. And here is our topic: how to exchange this information efficiently and correctly?   Analog way The oldest and probably the most recognizable protocol is PWM signal, taken from servo controlling. All the analog protocols are based on this signal. Period and duty cycle changes, but the idea remains the same: the FC sends a signal, and the ESC measures the time of the high and low signal, and this measured value is treated as a new set for the motor. The main features of this approach are: simplicity ...
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LERP, NLERP and SLERP

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WHAT IS THAT AND WHY DO YOU NEED THIS? Whenever you've got 2 numbers and you want something between them, you want some kind of interpolation. And the same in quaternions - you have to quaternions that describe the same no one is 100% correct but 100% incorrect either, so you want a quaternion that is a combination of these two. So you can use the simplest idea of combining two numbers: \[\mathbf{q}_{3}=\alpha \mathbf{q}_{1} +(1-\alpha)\mathbf{q}_{2} \label{eq:LERP}\] this is LERP ( linear interpolation ) but since, for orientation porpuse quaternion need to have norm of 1, after this interpolation you need to normalize result: \[\mathbf{q}_{3}=norm(\alpha \mathbf{q}_{1} +(1-\alpha)\mathbf{q}_{2}) \label{eq:NLERP}\] and that is NLERP ( normalized linear interpolation ) . Now, how these methods could be interpreted, and what are the consequences in real applications?  If we imagine a circle with a radius of 1 which is going across quaternions that we want to inter...
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How to develop STM32 with VScode? part 2/2

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  So far, everything was working only if you were using the same MCU as mine - STM32F405RGT. Since, arguably, not everybody is programming drones on this exact MCU, in this post I will show how to set up a project from scratch and along this way reveal a bit of the mystery of how everything works and what was the purpose of some files from a previous post. Luckily this will be the last part of this complicated process and ideally, after that, you should be able to develop any STM32-based board. Create a project structure Open the folder where you want your project and create new folders: Src , Drivers , bin , build , link . I keep the same folder structure among all projects so that I can just copy an existing one and change only MCU-specific parts. Of course, you can have different folder structures, but be aware of that and make suitable adjustments throughout this post.   Add files The next step is downloading and adding all essentia...
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