Multiprocessor system

[Clinton L. Corbin]

>Clint Corbin wrote:
>
>> I have been thinking about a fuel injection system composed of four 68HC11
>> microprocessors.  The first processor would run the ignition system.  It 
>
>I am working (slowly) on an idea like this, but not quite so ambitious,
>I think 4 processors is a little overkill.  My system will use 2 for now,
>one for ignition and one for fuel.  I know some guys who did a natural 
>gas injection system using 4 processors, but only 2 actually ran the
>engine, the other 2 were strictly for data aquisition and communications
>for developement purposes only.
>
>> There would be two seperate (and identical) fuel injection systems.  Each 
>> would control 4 fuel injectors.  For a 12 cylinder engine, one more fuel
>> injection subsystem could be added without change to the master controller.
>
>Por Que?  You could just add more injector drivers, unless you want full
>sequential.  Seems to me the software would be a nightmare for this kind of
>system.

That's the crux of the matter.  I want a fully sequential system.  The 68HC11
does not have enough output compare ports to control 8 fuel injectors in a
sequential system.  The software for the main modules would be pretty basic.
They would not have any of the advanced stuff in them, just the basics 
needed to properly run there system.  They would be told how to MODIFY either
the injector pulse or the ignition timing by the master controller.  The system
should be able to run without a problem without the master controller being
connected at all.  In fact, that is how I intend to build it: the ignition
system, the fuel injection system, and finally, the master controller to
impliment the more advanced features (such as ignition retard based on knock
sensors).  Because all of the modules are stand-alone, I do not need to use
the serial interface to connect all of the modules.

>As far as the code goes, you could use the 'HC11E2 which has 2k of EEPROM
>instead of EPROM.  This should be plenty of code space, since you're
>splitting up the operating system into several parts anyway.  You can put a 
>header on the circuit board, tied to the RS232 port on the 'HC11, and 
>reprogram the EEPROM any time with a laptop.  Don't even have to pull 
>the chip to erase or reprogram it.

Now this idea I like.  I just do not want to get into the postion were I have
to program the sub-modules through the master controller.  This leads to 
a level of complexity I do not want to deal with.  Yes, I know what most of
you are thinking.  And hey, you may be right.  I cannot PROVE that I am
sane.  Can you?  Basically, I am willing to put up with a bit more hardware
complexity to get rid of software complexity.  I find it easier to write
code that runs the ignition, code that runs the fuel injectors, and code
that runs the master, than to try to write one program that does everything.
Not to mention most microcontrollers do not have enough hardware resourses
(input captures, output compares, regular I/O ports, etc.) to run the system
the way I want it to run.  By breaking it up into modules, I have the 
hardware I need.  And it makes the system extremly modular.  Need a system
for a V-16 (hey, you never know)?  just use two ignition modules and four
injection modules.  One constant in each program would have to be changed.  
The master controller would not change at all.

And do you think we could drop this spelling crap?!?  That includes all of
the snide little remarks at the end posts.  Face it: the post that got all
of this started was pretty bad.  There were reasons for this.  Everyone
makes mistakes sometimes (my own spelling proves this often enough).  So
do you think that we can grow-up and leave this behind us?

Clint 
ccorbin at intel7.intel.com