Well, I hav comments for everybody so, I´ll try to be clear:

First: Steve and Jay: Please, don´t be dramatic. I´m developing this system for my thesis. I´m finishing my studies of Industrial engineer and I have to do that. I´m not interested in selling it, first of all, because i know that it won´t work properly, but, I´ll try to design it the better I can. I know you understand me.

Seteve: OR all the wheel events. That´s great! It´s simple and functional, like all the good ideas. I´ll try this on my design and I´ll let you know about the results.

Josh Bensadon wrote:
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Victor,
I am familiar with the ABS system on my car. This is what I know of it.
There are 4 wheel sensors, 3 reservoir systems.
Two for the front wheels and one for both rear wheels.
Each reservoir system has a motor that will remove execess fluid
(this you know) and also has a solinoid type clutch that will lock
that motor. This motor lock prevents the reservoir from filling by
the normal braking pressure.

If your system is working now with one wheel, then you don't need
to ask if your voltage/current is right... obviously it is.
To get 4 interrupts, just pick a processor with 4 interrupts *OR*
connect all wheel inputs to an XOR gate, then take the output
of the XOR gate and connect it to the input of another XOR gate (2)
and the input of a delay line. Output of the delay line into the
other input of the XOR gate (2). What the 2nd XOR gate & delay line
are for is to give an interrupt on any change of state (hi to low or low to high)

Also connect the wheel inputs to various I/O pins, and in your interrupt
routine, detect in software which input caused the changed of state int.

OR... use some kind of interrupt controller.... 8259???

BTW, have you thought about driving conditions???
Heat, Moisture, Cold, etc.... Automotive Electronics is not for amateurs.
Especially when there is life safety involved (ie, Braking system of vehicle)


Josh:
I can see that you are familiar with ABS systems but, as you know why I´m developing this system, let me tell you something:

As the system is for a truck, I don´t need to remove execess fluid because trucks uses air brakes. The execess of air is just trhown away (it is not a closed circuit) so... less problems.

I know that my design works with one wheel because I tested the code with a 8051 family emulator ('emily52' you know it?). That´s why I asked about voltage/current level. Tomorrow I´ll try this on a 80C552 and...we´ll see.

I have to use this uP because it´s the only one that we have in the university lab´s so... forget about changing.

I like the idea about XOR gates (similar to steve´s one) and I´ll try it.

Driving conditions? I don´t know if I will think about it in the future but now, I have more important things to think about.


Thank you everybody.


Victor.

PD:please, don´t argue.