old (1985) 68HC11 EVB schematics needed

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In '98 I posted the following:

Richard Erlacher   Sep 8 1998, 3:00 am
Newsgroups: comp.arch.embedded
Date: 1998/09/08
Subject: 68HC11 EVB Schematics, etc.

I have, after 10+ years, found that I've misplaced or lost my
schematics for the ORIGINAL (1985) 68HC11 EVB . . . you know . . . the
one they once sold for $68.11 to those willing to experiment with it.
My main interest is in obtaining the pinout for the 60-pin (?)
connector at one end, since that's where all the useable signals are

If someone has this information and is willing to share it, I'd be very

The schematic is also of interest, even if I am able to get the
connector pin definitions, though.



Well, because I was never able to find a copy of the "original"
schematic, I'm still at a loss ... particularly with respect to that
original connector, which, seemingly, was changed in later revisions.

The way to recognize this board version is by counting the 28-pin DIP
sockets.  My old board has two of them, at U3 and U4.  Since I'll
probably need to fiddle with the board some in order to modify its
resources, and since I'll want to use the signals on the 60-pin P1, a
scan of the schematic would be really helpful, just in case someone
happens to have it.  Back in '98, I got a number of pointers to later
versions, but, alas, those were not useable.

I'd be thankful to have this information.



Re: old (1985) 68HC11 EVB schematics needed

Quoted text here. Click to load it

I have a M68HC11EVB from around 1987 or so.  It's probably not the
original, though.  The users manual says: "Information contained in
this document applies to revision (B) M68HC11EVB evaluation modules,
serial numbers 1000 and up."

Checking the 28 pin DIP sockets, looks like this one has 3 at U3, U4,
and U5.

While I don't think it's the one you are looking for, let me know if
you think this will be useful and I'll pass the pinouts along.

Brian Dean
http://www.bdmicro.com /

Re: old (1985) 68HC11 EVB schematics needed

I know this sounds tedious but if you want to check the connections you
could just use a contiuity tester to find the pin to socket
connections. I'd start by eliminating ground and power first as there
maybe a few sprinkled in that connector.


Re: old (1985) 68HC11 EVB schematics needed
Yes, such an effort is tedious.  Its result is also ambiguous.  As time
allows, I suppose I'll end up with enough information to make this
thing useful again.  There are a very few power connections.  There are
also some differences between the original and subsequent versions, I'm
told, though the pinout was maintained after the rev B boards were
released, and corresponding changes in the monitor firmware made as
well.  I got this information from a fellow at MOT back in '98 when I
first started pursuing this matter.  

Thanks for your input.


Re: old (1985) 68HC11 EVB schematics needed
If you have a logic analyzer, you can have the M68 write to mem
addresses in a counter like fashion. Looking at the screen you should
be able to decode the address lines at least. Once you have that you
can force it to write the counter value to a fixed address and from
that decode the data lines. In both cases, as you get closer to the MSB
the switching frequency halves.


Re: old (1985) 68HC11 EVB schematics needed
I'd be happy to have a look at the connector pinout, if only to check
against what I have "beeped out" so far, but my goal is to fool with
the decoding logic in order to put a 32KB battery-backed RAM in place
of the EPROM at U3 and a similarly sized SRAM at U4 with physically
present I/O carefully mapped out of the SRAM region.  While this is
readily achievable with a fully documented board, the common practice
of ambiguously decoding I/O on SBC's makes it risky to rely on such
decoding for information in this case.

If you have a connector pinout that you'd like to share, I'd be happy
to check it out.  I'll have to search further for documentation for the
original, 3Q85 board.  Sadly, that board has no identifying features
visible with the components installed, that would make it uniquely
identifiable.  It simply has "M68HC11EVB" silkscreened in its lower
left corner.



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