Embedded Flight Controller Tutorial

This is an excellent series. I'll post the links here because I keep losing them:

• Project 1: Custom Flight Controller Part 0: Overview
• Custom Flight Controller Part 1: A Simple Revision on Quadcopter Flying Principle
• Custom Flight Controller Part 2.1: Getting the Orientation --- Get Data from MPU9250 Sensor Module 
• Custom Flight Controller Part 2.2: Getting the Orientation --- The Quaternion Kalman Filter
• Custom Flight Controller Part 2.3: Getting the Orientation --- The Matlab Simulation 
• Custom Flight Controller Part 2.4: Getting the Orientation --- Migrate to STM32 
• Custom Flight Controller Part 2.5: Getting the Orientation --- QKF on STM32 
• Custom Flight Controller Part 2.6: Getting the Orientation --- Using Interrupt to Get Data from MPU9250 
• Custom Flight Controller Part 2.7: Getting the Orientation --- Mag Calibration and Overall Algorithm Structure. 
• Custom Flight Controller Part 2.8: Getting the Orientation --- Processing Orientation Visualization

And here's a link to the code on GitHub.

Thank you Lyfkyle, great work!