I have a question - I've been going through the pin usage of an RCM3200 in a
project I didn't develop from the beginning, as a part of checking into
compatibility of new graphic LCD controller chip I need to move to.. And
also taking the opportunity to identify pins that might be free for future
upgrades, I have found that we are actually using PD7 in our application
(which I never thought was a problem, because it always worked) as the reset
signal for our LCD module. And I can confirm that looking at it with a CRO,
it does actually provide a reset function to the LCD, as expected from the
code..

Only thing is - that the rabbit 3200 user manual says this pin is reserved
for future use. (P30/24)

http://www.rabbit.com/hottag/download.php?ht=/documentation/docs/manuals/RCM
3200/UsersManual/RC3200UM.pdf

and from the schematic of the RCM3200 I can see that these pins are
alternatively connected to the Ethernet data I/O.

Now. Obviously we HAVE been using this pin over a few years, and multiple
iterations of RCM3200 boards. And we use Ethernet in this app with no
problems.

But now I think, well. if PD7 isn't causing any problems, the others
shouldn't either - I could do with using PD2, PD3, and PD6 for other
features, too.

So what's the deal with port D pins 2,3,6,7? Does anyone else use them? Do
they work fine as both ins and outs?

Thanks,

Julian Higginson

Bruttour International P/L

http://www.bruttour.com.au

Ph: +612 9987 1581



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--- In r...@yahoogroups.com, "Julian Higginson"
wrote:
> So what's the deal with port D pins 2,3,6,7? Does anyone else use
them? Do
> they work fine as both ins and outs?

Some of families of Rabbitcores include a model that has the Ethernet
chip on board, but not the physical connector (e.g the RCM2210
with "raw signals only"). This allows people to use the Ethernet
capability, but with their own connector - perhaps because they want
the connector away from the Rabbitcore, or at a different height, or
want it hardwired to something else. It also allows Rabbit to use the
same PCB layout for several different models by fitting different
components as required.

It's most likely that they planned to introduce such a variant to the
32xx family but never got around to it. As they try to make the
different models as pin-compatible as possible, and cover them with
the same User Manual, the "reserved" warning just tells you that a
different model might not have these pins available for the same
purpose. I'd be perfectly happy to use them as regular I/O pins in a
design. If they ever did get around to using them for something else
it would almost certainly be with a different part number. Same goes
for your other question about PE0 - just checked the schematic and
it's not connected to the Ethernet chip on any of the current 32xx
models.
------------------------------------



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Hey Finbarr,

Thanks for the information!

The whole reserved pin thing is a bit scary, but I see where they're coming
from with that now.

I have some experimental changes I'd like to prototype on this next PCB, and
those pins would be really handy. I'll connect them via 0R links anyway, but
it's nice to know the experimental changes I want to try will not be dead in
the water due to using unavailable pins.

I already had a bit of a problem last time I tried some optional
experimental feature: a 1-wire interface using portB pin 7. that was when I
learned about the Aux I/O feature and port B.. though luckily in that case I
could do my development testing by removing a 0R link and wiring straight to
port B pin 0. and this new build needed changes for other reasons anyway, so
no money wasted on design mistakes so far - but it would have been nicer to
just have known I couldn't use most of portB for other things in combination
with Aux I/O.

Julian Higginson

Bruttour International P/L

http://www.bruttour.com.au

Ph: +612 9987 1581

From: r...@yahoogroups.com [mailto:r...@yahoogroups.com] On
Behalf Of Finbarr
Sent: Wednesday, 15 October 2008 9:18 PM
To: r...@yahoogroups.com
Subject: [rabbit-semi] Re: RCM3200 Port D pins 2,3,6, and 7 - are they
actually meant to work???

--- In r...@yahoogroups.com ,
"Julian Higginson"
wrote:

> So what's the deal with port D pins 2,3,6,7? Does anyone else use
them? Do
> they work fine as both ins and outs?

Some of families of Rabbitcores include a model that has the Ethernet
chip on board, but not the physical connector (e.g the RCM2210
with "raw signals only"). This allows people to use the Ethernet
capability, but with their own connector - perhaps because they want
the connector away from the Rabbitcore, or at a different height, or
want it hardwired to something else. It also allows Rabbit to use the
same PCB layout for several different models by fitting different
components as required.

It's most likely that they planned to introduce such a variant to the
32xx family but never got around to it. As they try to make the
different models as pin-compatible as possible, and cover them with
the same User Manual, the "reserved" warning just tells you that a
different model might not have these pins available for the same
purpose. I'd be perfectly happy to use them as regular I/O pins in a
design. If they ever did get around to using them for something else
it would almost certainly be with a different part number. Same goes
for your other question about PE0 - just checked the schematic and
it's not connected to the Ethernet chip on any of the current 32xx
models.



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