In message <20090202020857.stbzev6v68cc4...@webmail.pdx.edu> you wrote:
> An application layer that floods the bus (but doesn't
> invoke transceiver safeguards) will cause enough error
> frames that the CAN controller will go "bus-off" and stop
> transmitting.
So there are limits on the amount of bus bandwidth a single
application can legitimately consume? What are these
limits? Is there a reservation system for applications, or
is it just a total bandwidth thing? I guess I'm a lot more
ignorant of CAN than I supposed.
> Either way, if you have reservations to the idea of using
> CAN, then please allow those of us that are interested in
> it to give it a try. We aren't slipping any schedules to
> get it done, so there is no harm.
I don't have any reservations about using CAN. In fact, I
think that so many key folks are so obviously so
uncomfortable with USB that it was stupid that we agreed to
it in the first place and put a lot of work into getting it
going. Putting more work into making it work better would
be even stupider, in my opinion.
It turns out USB is apparently total lily-gilding. We
(putatively) are buying a bunch of things we really don't
*need*---higher bus bandwidth, convenience, cost, chic,
etc---in return for a bunch of things we really don't
*want*---reliability questions, development effort. Bad
tradeoff.
IMHO, if you get CAN working quickly we should ditch USB and
just use CAN and live with the bandwidth and other
limitations, at least for now. One avionics bus is plenty,
especially for this first flight.
Bart
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