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old (1985) 68HC11 EVB schematics needed

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 presented.

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

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

thanks,

Dick =========================================================

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.

thanks,

Dick

Reply to
edick
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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

--
Brian Dean
http://www.bdmicro.com/
Reply to
Brian Dean

Hi,

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.

-Rex

Reply to
Correlious

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.

thanks,

Dick

Reply to
edick

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.

Dick

Reply to
edick

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.

-Rex

Reply to
Correlious

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