[Paparazzi-devel] CAN on Lisa

[Tilman Baumann]

Hi,

I'm fooling around with can at the moment. A friend and I want to 
modularize UAV components a bit more.

The easiest and lowest hanging fruit seems to be to just pass telemetry 
messages on the bus first. (probably inspired by one of the data logging 
modules)
But anyway. I'm not there yet. First I like to play around with CAN raw. 
I thought the code is now based on libopencm3. But 
./sw/airborne/arch/stm32/mcu_periph/can_arch.c is totally different.
Eventually I don't care really what I use. But what is it that is being 
used there and how can I learn about it?
Has anyone already used that stuff? I suppose the code is there for a 
reason?
Would it perhaps be a better idea to scrap that and use the libopencm3 
functions? Would they work?

And while this is not my concern yet, I would not mind starting some 
kind of conversation about this before I start hacking.
My current idea is basically to just dump ppz format messages on the bus 
with a prefix to make them filterable. Later additions would be a 
message type for actuators. (Have not quite grokked if or how I can have 
multiple Actuators like CAN servos and PWM servos)
And then of course telemetry receive via CAN and sensor values receive 
(remote virtual ADC would be cool).
I guess conversation topics could be the message format. I think the ppz 
format is the easiest way right now. But perhaps there are better ideas.

Grand vision is to have little can modules (NXP Cortex M0 based 
processor probably) which drive servos, run actuators and read sensor. 
Connector could be RJ45.
This would make wiring much less crazy and planes become more 
maintainable. Imagine having just one JR45 connector going to each 
detachable wing and your camera subsystem and what not.
Also telemetry could become more flexible, radios could be placed where 
ever is most convenient.