Introduction

Hi! Thanks for stopping by.

Your first question probably would be “What is this blog about?” As the name implies, it is about building from scratch quadro- or multi-copter flight control board – the “brain inside the machine” that is responsible for letting it fly.

There is a multitude of flight control boards on the market today – AeroQuad, ArduCopter, DJI, KK, MultiWii - just to name a few. A rather large list of these boards provided at http://robot-kingdom.com/best-flight-controller-for-quadcopter-and-multicopter/, but if you search Google, you probably find many more. So if your interest is in just flying a multicopter or building one and then flying it – you would be much better off just buying either a kit or a RTF set.

This blog goes into the details of building the board and developing firmware for it from scratch! That is from the bare-bone MCU – no external libraries, no black-box code – everything is here and everything is explained. All the code that will be discussed here is available at https://code.google.com/p/custom-pic-quad/ under the Open Source MIT License – look at it or use it at your own discretion WITHOUT ANY WARRANTY; without even the implied warranty of   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

The version of the board and corresponding firmware that will be discussed here is for the Version 3 of the board, which I am working on now. Thus, I will be publishing new articles for this blog as my development effort progresses. Is there a promise that I will conclude this effort and do not leave you, my readers, halfway there? I think so. I have been working on flight control boards since about 2004. While the first couple of revisions (starting with Version 0) were total failure, I finally succeeded with the Version 2 (code and Eagle files for the board itself are at the link above), which happily carries my quad in the air - https://www.youtube.com/watch?v=kEo5DSe7PDg.  If you are interested, more details are provided on the Project History page.

So why don’t I blog about the working Version 2? Oh, it is boring! Since then I got some new idea, improved code, designed much better board, etc. – so why bother with the old stuff when we can together delve into the new one?

Another reason for this blog is rather selfish – while working on Version 2 I implemented a lot of calibration of the sensors like calibration of magnetometer for Hard and Soft-iron interference (Application notes AN4246 and AN4248 from http://www.freescale.com/) and temperature compensation and calibration of InvenSense IMU MPU-6050. Yes, I have some Excel spreadsheets hanging around from that time, but I did not document all of those efforts properly to assist me in calibrating sensors on my new board. Now I plan to document calibrating sensors on my new board in this blog, so when I get to the next iteration (maybe, Version 4 or 5) I will have all my notes readily documented in this blog! This also applies to sensor fusion, PID tuning, etc.

If you stayed with me up to here, you probably would be interested in what is so special about my project and what is the overall architecture of my board and the corresponding firmware? That will be the topic of the next post.