On Sat, 9 Feb 2002, guitarlynn wrote:
> OK, a little back-ground on me, so maybe this makes a little more
> sense to follow. I have had 3 years of electronics schooling, a
> little over 2 years of Electrical engineering, and been a licensed
> electrician for around 4 years after a 5 year apprenticeship with
> specialties in digital control design and instrumentation.
>
> This doesn't mean a hill of beans other than I have a small notion how
> digital electronic devices are controlled on some level. My logic
> is somewhat different than a programmer when looking at devices
> such as data drives much of the time. I've been posting my thoughts
> without really going into an explanation of any depth ... maybe this
> will clarify what _is_ going on in _my_ head.
The altered states to start to come into focus. :)
> > > a zero-ohm resistor is for circuit protection and yes pin 30 is
> > > ground on regular IDE as is pin 2.
> >
> > What does "circuit protection" mean?
>
> Ok, let's assume something internal in the ADM shorts out in a bad
> place We will also assume you are using the ADM as designed to use
> software via a special IDE controller to specify when and what is
> write-protected. This resistor has _no_ effect on the circuit _other_
> than limiting the amount of current and voltage running across it.
> It technically should overload and burn out this resistor and protect
> the precious motherboard you just paid all this money for.
This is a cmos logic device.. not a power driver. It will not burn out
any resistor. You often see resistors inline to limit current (say, for
LEDs or transients from off-board inputs), but these are NEVER zero ohm
resistors.
> In reality, this is almost never the case, but it is accepted good
> engineering practice from my experience.
A zero ohm resistor is a piece of wire. It is not a fuse. I would
recommend that you re-read Charles Steinkuehler's analysis for the most
likely function of this (most likely not installed) piece of wire.
[...]
> > Can I be a little lazy and ask you what the logic is that
> > your trying to accomplish? What does grounding the reset
> > line do?
>
> Something that will allow me to write-protect an IDE flash or CF drive
> in a 1U half-slot rack case. Write-protection will be pure hardware
> ideally. Maybe I'm just nuts, but it's lying there working as I wanted
> right now.
It seems to me that tying reset low would prevent the interface circuitry
from working... that is, the device would be write protected, but it would
also be read protected, so if it lost power you would have to physically
be there to enable reboot. This would _not_ be ideal.
---------------------------------------------------------------------------
Jeff Newmiller The ..... ..... Go Live...
DCN:<[EMAIL PROTECTED]> Basics: ##.#. ##.#. Live Go...
Live: OO#.. Dead: OO#.. Playing
Research Engineer (Solar/Batteries O.O#. #.O#. with
/Software/Embedded Controllers) .OO#. .OO#. rocks...2k
---------------------------------------------------------------------------
_______________________________________________
Leaf-devel mailing list
[EMAIL PROTECTED]
https://lists.sourceforge.net/lists/listinfo/leaf-devel
