Brief overview of a micro controller v. micro processor.


*A microcontroller is a specialized form of microprocessor that is
designed
to be self-sufficient and cost-effective, where a microprocessor is
typically designed to be general purpose (the kind used in a PC).
Microcontrollers are frequently found in automobiles, office machines,
toys,
and appliances.
The microcontroller is the integration of a number of useful functions
into
a single IC package. These functions are:

The ability to execute a stored set of instructions to carry out user
defined tasks.
The ability to be able to access external memory chips to both read and
write data from and to the memory.

Basically, a microcontroller is a device which integrates a number of the
components of a microprocessor system onto a single microchip.

So a microcontroller combines onto the same microchip :

The CPU core (microprocessor)
Memory (both ROM and RAM)
Some parallel digital I/O
Also, a microcontroller is part of an embedded system, which is
essentially
the whole circuit board. Look up "embedded system" on Wikipedia.
The difference is that microcontroller incorporates features of
microprocessor(CPU,ALU,Registers)along with the presence of added features
like presence of RAM,ROM,I\O ports,counter etc.Here microcontroller
control
the operation of machine using fixed programme stored in Rom that doesn't
change with lifetime.


http://wiki.answers.com/Q/What_is_the_difference_between_a_microprocessor_an
d_a_microcontroller

Nevada Bruce

Most of the answers are here.
http://www.rotaryeng.net/fuel-injection.html
And here.

http://www.rotaryeng.net/mech-fuel.html

Paul Lamar


Bruce
I looked into PLC engine control a while back. Here are some of the things
you will need in a micro PLC

Multiple high speed counters with appropriate output impedance. Many are
capable of 20 kHz.
12 volt cpu unless you want to add a dc converter
Thermocouple inputs if you want to monitor temps.
A handful of 12 volt dc I/O
Most have 10 or even 12 bit analog but may be limited with above options.

If you can't meet all those conditions then you end up adding additional
hardware and the PLC quickly looses its advantage. I noticed also that
some
units have PID capability- Paul would PID loop make the tuning logic any
simpler?

It is hard to find all those things in a fist sized low cost box but keep
looking-I ran out of time. The stepper motor motion control stuff usually
has a bunch of high speed I/O -so maybe something in that niche.

Rick Pickett

"A Proportional–Integral–Derivative controller (PID controller) is a
generic control loop feedback mechanism (controller) widely used in
industrial control systems. A PID controller calculates an "error"
value as the difference between a measured process variable and a
desired setpoint. The controller attempts to minimize the error by
adjusting the process control inputs."

That is widely used in low RPM low power automotive EFI systems but
so far not used in aircraft EFI systems. I was thinking of trying it and
use EGT as the controlling input. The tricky part is there are
two sides to the curve. The EGT first increases and than starts to
decrease past peak EGT.

Paul Lamar


Paul,

I did not know we were discussing PLC for engine control. I thought the 555
was the way it was headed. I also was under the impression that perhaps a
DOS computer was going to be used on a test install on a dyno / engine to
find the parameters for the 555? Please set me straight thanks.

Joe berki
Limo EZ


I have two systems I am working on. The 555 and a PC based systems.
The 555 is more or less done. Mother boards are getting real cheap
and much smaller.

I gave up on the DOS approasch as DOS does not support USB.
The Hytek Automation USB data acq system has all the hardware we need
for $90 along with a $80 PC mother board.

Real time Linux supports everything and Hytek provides some Linux
C source code to build on. George L got the Linux Hytek C source to
compile on real time Linux. See EMC for NC mills for more info.

Paul Lamar