Re: [Paparazzi-devel] Does the Lisa/L support ESC controllers for Rotorcraft?

[Piotr Esden-Tempski]

Hi,

On Jul 15, 2011, at 9:23 AM, Simon Wilks wrote:

> Hi,
> 
> I picked up an XAircraft X650 recently and just finished building it and gave 
> it a first test flight. Very nice :) Here is a brief build log if you are 
> interested: http://sites.google.com/site/paparazziuav
Nice page, I hope you will get your Aspirin soon! :)

> I have a Lisa/L board and was planning to adapt the X650 for it. I was 
> initially thinking I would need to at least replace the ESCs with I2C 
> controllers but I was wondering if the Lisa/L (code) supports driving ESC 
> controllers. 
Yes it does. There is a PWM supervision module there.

> I understand one of the problems with ESC is it is too slow but XAircraft 
> seems to have come up with something new that provides 500Hz control. Here is 
> a link to an article on the UltraPWM protocol and the reason they stayed away 
> from I2C: http://www.xaircraft.com/wiki/UltraPWM/en 

We are running all our aircraft on PWM based ESC's. Most china motor 
controllers will accept higher frequency PWM input then the nominal 50Hz, 200Hz 
was enough to get a stable Quad and 400Hz makes it nice and smooth. In my 
opinion I2C is evil, error prone, unreliable and a single point of failure. PWM 
or PPM is much more robust to EMF. I2C was designed for short connections 
between components on one single PCB not to run through half a meter of wire. I 
personally had lot's of headaches associated with I2C in the past.

The only even better solution would be CAN. (lisa/l supports CAN but the only 
motor controller that has CAN support at the moment is http://open-bldc.org and 
it is sadly still not production ready, yes it is my fault ... I still did not 
clone myself to have enough time to finish it :/ )

But enough of the rant. Yes Paparazzi and Lisa/L supports PWM based motor 
controllers and yes it also supports high frequency PWM. So go for it and use 
it! :D

Cheers Esden