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In message <ab027e0902021003667d@[128.83.128.21]> , you write:
| Question:
|
| If a true CPU is used in a controller ( like
| John's 68HC000 EFI board ) instead of a
| microcontroller, what compnents are needed?
|
| This seems quite difficult!
No.... as you will see :) ....
| But most importantly, how do you do
| real-time input/output interrupt based events?
As easily as any other chip. 68k, for example, has
192 user interrupt vectors; however, I run the
EFI68k in "autovector" mode with only seven.
There is nothing special about any of the
microcontrollers other than having incorporated may
of the commonly added devices like
timers/pio's/UART's etc. If you want to see
something neat, look at the 68302 which has a
CPU32 core *and* a RISC communications processor.
| We need real-time INPUTS for the crankshaft
| and cam position sensors, and real-time OUTPUTS
| for all injectors.
|
| Is there some special chip that works right
| on the bus to handle this?
Yes, the SSI67F687 was one such chip mentioned here
on this list. Silicon Systems was more than happy
to send me some of there propaganda. I also believe
I could use a 82C54 with a GAL or two (... flywheel
tooth counter and a PLL ...) to do this also.
| I know the 68hc11 has over 70,000 transistors
| in the IC/OC (input compare/output compare)
| section for the real time stuff.
Don't be impressed by transistor count; we aren't
building AM radios in the early seventies here.
General purpose programmable timers have been around
for decades. That's how Motorola knew what to
put in the 68HC11!
If we were going to produce thousands of these EFI
controllers, then the choice of processor would be
important to reduce cost. As we (I) am only making one
or two of these things, my choice is to make
a controller generalized enough to be used in something else
and to create a friendly software environment so I
don't spend all my time writing software. I'm not vary
concerned with the chip count.
John S Gwynne
Gwynne.1 at osu.edu
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