Adding Flapper platform and handling servomotors

[matejkarasek]

This PR adds a "flapper" platform, together with a "flapper deck", default settings and gain values.
To enable servomotors, which need a non-zero neutral value, additions were made also to motors.c and supervisor.c
(This is a clean version of #1123)

Finally, I include some cleanup after #1121.

[matejkarasek]

The Python bindings might require some extra work such that they function correctly with the Flapper...
If the second power distribution is included, the build test fails...

[tobbeanton]

Overall I think it looks good! There are two discussion points I can identify though:

1. The servo integration in motors.c is starting to make this file quite large. Maybe it is time to split it up and have a servo.c and maybe a higher level actuator.c file. This is quite a large change though...
2. There is a potential conflicting PR Bigquad early access fix #1131 which is changing the external battery monitoring functionality a bit. Which one is easiest to merge first? Probably PR Bigquad early access fix #1131 since it is smaller.

[krichardsson]

I think this generally looks good!
I mainly have some comments related to ifdefs based on platform, see comments in the code.

[matejkarasek]

Overall I think it looks good! There are two discussion points I can identify though:

Thanks, @tobbeanton!

1. The servo integration in motors.c is starting to make this file quite large. Maybe it is time to split it up and have a servo.c and maybe a higher level actuator.c file. This is quite a large change though...

I agree. In fact I have started working on another PR that should enable more than 4 motors/servos:
https://github.com/flapper-drones/crazyflie-firmware/tree/more_motors

So how about if I introduce the servo & motor separation there?

EDIT: after digging more into the code, this would require much larger change than I thought... Don't think I would find time to do that myself, but am willing to contribute.
Let me know how you feel about the current workaround.

2. There is a potential conflicting PR Bigquad early access fix #1131 which is changing the external battery monitoring functionality a bit. Which one is easiest to merge first? Probably PR Bigquad early access fix #1131 since it is smaller.

I agree it is easier to merge #1131 first

[matejkarasek]

I think this generally looks good! I mainly have some comments related to ifdefs based on platform, see comments in the code.

Thanks for the quick review @krichardsson
Will fix try to fix these soon

[matejkarasek]

All the issues are fixed, pls let me know if this works.
And also whether I should do anything about #1131.
Thanks!

[knmcguire]

Hi! I just did a test flight with our flapper with a controller and the cfclient and it had a major forward pitch eventhough I didn't control it that way. I tested different versions (we have revD):

• This PR: major forward pitch
• The new firmware : Forward pitch (not sure if it was the same though)
• The old firmware before kbuild: All good

Could you try it out and see if you see the same?

[matejkarasek]

@knmcguire Thanks for testing it out!

Have you trimmed the servos (especially the pitch servo) after the firmware update? It is stored as a permanent parameter, and I have changed the name of the parameter group from "_flapper" to "flapper". So you have to do it after this firmware update...

[knmcguire]

Yes that's it! the flapper.servPitchNeutr had to be adjusted. It was set to 50 but I had to change it to 58. Let me discuss with @krichardsson if there was anything else but if that is it, we'll merge it soon!

[krichardsson]

Looking nice and clean!
Merged
Welcome flapper!

[matejkarasek]

Wohoo! Awesome, thanks!

Yes that's it! the flapper.servPitchNeutr had to be adjusted. It was set to 50 but I had to change it to 58. Let me discuss with @krichardsson if there was anything else but if that is it, we'll merge it soon!

The default value is close, but not exact, this varies from Flapper to Flapper (or from servo to servo, to be precise). The same applies for the yaw servo, though there it is less critical...