Old 486 Board for ECU??

[Diehl, Jeffrey]

PS issues:
Yes, we need the +/- 5 and 12 V.  No, we don't need that big xformer to
generate it.  Just us a pair of regulators.  As long as you don't go nuts
with hard drives and such, you should be able to regulate plenty of current
to run the board.

Post:
Booting the machine once and simple suspending it from then on is a
wonderfull idea!  But how many motherboards support this?  Most of the
boards I have laying around are from desktop boxes...

Quick Boot:
I love linux, but isn't that a bit of overkill?  Do you really need that
much power?  I agree it would be nice to have networking, mp3, and browser
configuration capability in my auto-computer, but...  On the other hand, it
is stable.  There are good development tools.  And software is easy to
write...  You might be onto something here.  And if you had wireless
ethernet... <slap>

On the other hand, you might consider RealTime Linux or FreeDos.  I also
recall seeing LCD displays for PC's with Linux drivers...

Just my $.02.

Mike Diehl,
MR-2, '87na

-----Original Message-----
From: Frederic Breitwieser [mailto:frederic at xephic.dynip.com]
Sent: May 01, 2000 9:05 AM
To: 'diy_efi at diy-efi.org'
Subject: RE: Old 486 Board for ECU??


Power Supply Issues:
Actually, the PC requires +/- 5V, and +/- 12 V. Most system boards can
"survive" without the negative power supply connections, as they are
generally only used for Intel Above Board memory cards (if you remember
those) and of course, the RS232 serial lines.

The problem with dropping these voltages is that there is a line on the
system board that provides a signal to the power supply, and its called
"power good".  Without this line working properly, meaning all four voltages
plus ground are there, most modern system boards won't boot.  Every
manufacturer impliments this differently, so your mileage may vary.

I have an old Micronics 486 all-in-one system board that has three slots on
a riser card, which I'm not using (I yanked it), and built in video, IDE,
par/ser, etc, and can boot off a CDROM drive.  Without the negative
voltages, this system board boots, but the RS232 ports fail the POST
process, requiring pressing F1 to continue.

>I wonder how quickly your car will "boot up" if it has to boot from
>floppy...  This is a (minor?) concern.

POST testing takes anywhere from 5 seconds to a minute depending on the
options/features you have enabled, as well as the amount of memory, and the
size of the hard drives.  Larger memory/peripherals obviously take slightly
longer.  Some system boards you can shorten this by enabling "quick POST" or
something similar.  Still, there is a delay between applying power and
usability.  A lot of the newer systemboards have a "green mode" where by a
motherboard timing circuit powers down everything due to inactivity.  Some
systemboards even have a jumper to force this.  Laptops have this, and its
called "resume".  If you use a system that supports this, you can "boot" the
car once, then leave it in "suspend" mode, so usability after turning the
ignition key will be drastically shorter.

Quick Boot:
I think Axel suggested writing your own POST.  We are doing this now, and
haven't finished it enough to test it, but the idea is to have the POST make
assumptions.  Assume the memory is 64mb.  Assume the drive is "X" size.
Assume both are present.  This way, the only delay is the drive spinning up,
which in our case, would be drive "D" anyway.  Drive "C" is an ATA/IDE flash
card that has an ide adaptor plugged into the system board.  200mb, with
Linux installed.

Java:
I don't think Java would be fast enough on a simple systemboard (286/386)
but its worth investigation.  We are using gcc, which comes with Linux.  C
is one of the more portable languages, which Java is certainly comparible in
this regard, but its compiled, resulting in "machine code" rather than "java
executables".  I think it would be easier to use C which is much more
stable, been around longer, and no more difficult to learn than Java.

But, for humorous reasons, I will say, it would be neat to use a web-browser
to reconfigure your EFI maps.  :)
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