[Paparazzi-devel] Paparazzi on Linux and Lisa design questions

[Tilman Baumann]

Hello,

I have been follwing this project and the list passively for some time now
and I think I know pretty well how it all works together, and I expect the
rest to come to me when I use it.

I'm getting my airframe soon, which I will fly RC only for a while before
I make it 'smart'.
But since I like to thoroughly think things through very early, I'm having
some ideas or rather questions now.

I like the idea of running the paparazzi airborne software on a linux
system like gumstix. I'm comfortable with linux, I can expand it wherever
I want and there will be enough performance no matter what I do.
UDP telemetry, wifi, mesh networking, digital video stream via wifi and
all those kind of things.
My initial idea was to start something based on Marcus Wolschons efforts
of porting paparazzi to Linux.
However, as it turns out, the question of how to get IO into the system is
still open. So I would need to hack some IO interfaces, (ADC, Radio
decoder, servo output and so on) on a daughter board like Robostix. (Or
BeagleBoard Trainer if I go with the BeagleBoard).
But that would be a lot of work, and quite frankly I'm not really sure
where to start.

So far to my ideas and personal preferences.
I have to say the paparazzi Wiki does not really do a god job of
explaining the architectural differences of the different autopilots.
It took me a very long time to realise that Lisa probably is exactly what
I was thinking about, just already built and working.
It seems a bit like the coming back of the Classix approach, which I like
for some reason.

See
http://paparazzi.enac.fr/wiki/Lisa#Software
- Poine/booz2_a8 : this is a biplan with asctec motor controllers and
using stm32 only as io processor - this one is in progress

That was the hint that gave me that idea. So I'm thinking. Do I understand
that correctly? How much sense do my ideas actually make?
Lisa is expensive, is it really worth it?
Can somebody maybe point me to some resources on Lisas architecture? I was
trying to understand it from the source code side of things, but all that
paparazzi build logic is not making it easy for me at the moment.
What parts of the code run where and how is that determined?

I know those questions are a bit random at the time. But I was banging my
head against those thoughts over the weekend and are not much smarter then
before. Part of the problem is that I at the moment don't have a machine
where paparazzi compiles on (I will fix that soon).
I would appreciate if you could share your thoughts on Lisa and or my
ideas of a linux based autopilot. With the right pointers, I should be
able to find my way again :)

Thanks
 Tilman Baumann