Re: CPU recommendations from an Ada perspective?

[Marin Condic <condicma@bogon.pwfl.com>]

Mike Silva wrote:

> I'm reluctant to ask this question because it's so vague at this point, but
> my curiosity has won out.  I'd like to hear any recommendations for (or
> against) those 32 bit CPU families which are supported by good Ada tools.
> The project would be a large engine controller, with control loops running
> at 5 mS, 20 mS and 2 sec (don't yet know the details on the calculations
> involved).  Rough industrial setting (temperature extremes, electrical
> noise, etc).  We'd probably by COTS hardware, but that's not entirely
> decided.  Any opinions / experiences?
>

FWIW, we've built engine controllers out of M680x0's and Mil-Std-1750a's and
had no real hardware problems with them. Ada support has been mostly with the
XD-Ada compiler for both targets. We plan on doing the next generation of
control using the PowerPC chip. Of course, all the electronics are custom built
for the harsh environment and we're not using the dime-store cheapo chips
either. (It used to be all Mil-Spec hardware until the Mil decided to stop
Spec-ing it.)

We've also mucked about with a computer built for the Dodge Neon which was
encased in jello and would have been expected to drive a rocket engine. (Due to
cutbacks and the fact that all us software guys are quitting, it will never
drive a real engine so we probably won't find out if chilling it down and
heating it up would make it break. ;-) Of course it was entirely too small to
do much of anything besides turn some valves on and off and hit the igniter.
You couldn't do much in the way of any real serious control laws with this box.
{No Ada, either :-( }

The 1750a just barely had enough room to do "real" control laws for a rocket
engine and I don't think we could get the rad-hard versions of the chip anyway,
so its pretty dead.

For us (or, more realistically, those who will follow after me) the future
looks to be PowerPC with the Aonix compiler. You never get everything you want,
but the setup looks pretty good!

MDC
--
Marin David Condic
If you hurry, you may still find me for a while at.......
Real Time & Embedded Systems, Propulsion Systems Analysis
United Technologies, Pratt & Whitney, Large Military Engines
M/S 731-95, P.O.B. 109600, West Palm Beach, FL, 33410-9600
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