This is a GIT branch for the YMFC-AL code. This code was made by Joop Brokking and you should visit his site: http://www.brokking.net/ymfc-al_main.html

Thank you for downloading the YMFC-AL software package. 

Current version: 1.2 - July 12, 2016

Content:
YMFC-AL_setup.ino
YMFC-AL_esc_calibrate.ino
YMFC-AL_Flight_controller.ino
YMFC-AL_scematic.jpg

Revision update:
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Version 1.2 - July 12, 2016
The last code did not fix the complete problem so I had to make another adjustment to the code. The acc_x and acc_y values can also be negative so a simple smaller or greater test does not work.
Therefor I changed the code to:

if(abs(acc_y) < acc_total_vector){                                        //Prevent the asin function to produce a NaN
  angle_pitch_acc = asin((float)acc_y/acc_total_vector)* 57.296;          //Calculate the pitch angle.
}
if(abs(acc_x) < acc_total_vector){                                        //Prevent the asin function to produce a NaN
  angle_roll_acc = asin((float)acc_x/acc_total_vector)* -57.296;          //Calculate the roll angle.
}

This prevents a division by zero and the input value for the asin function will always be smaller than 1.
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Version 1.1 - July 11, 2016
There was a NaN (not a number) problem in the code. When flying more aggressive the quadcopter could become uncontrolable. The NaN problem is caused by the following:
When the absolute value of acc_y or acc_x becomes larger that the acc_total_vector the values provided to the asin function is larger than 1 and the asin function produces a NaN.
It recovers when the acc_total_vector becomes larger that the acc_x or acc_y values. But due to the complimentary filter the NaN error persists.
This problem will only occur when flying aggressive / fast descents. 

I changed the code as followed:
from:
angle_pitch_acc = asin((float)acc_y/acc_total_vector)* 57.296;            //Calculate the pitch angle.
angle_roll_acc = asin((float)acc_x/acc_total_vector)* -57.296;            //Calculate the roll angle.

to:
if(acc_y > acc_total_vector){
  angle_pitch_acc = asin((float)acc_y/acc_total_vector)* 57.296;            //Calculate the pitch angle.
}
if(acc_x > acc_total_vector){
  angle_roll_acc = asin((float)acc_x/acc_total_vector)* -57.296;            //Calculate the roll angle.
}
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Version 1.0 - July 3, 2016
Release
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