8-bit with external memory bus

jerry_s — Tue, 17 Mar 2009 17:23:26 GMT

Hi all good people,

Firstly I must admit I'm doing just hobby project, so be indulgent, please. Some of us are doing goofy things in their spare time, like bringing 8080 or 6809 systems to life.

last year I migrated very old design, running at MC6800 to MC6809. Now I'm considering a portable version of this, but I'm facing the fact the old NMOS chips are somehow power hungry and my aim is to keep current consumption under 40mA.

Because in my work I'm using different family of MCUs, my knowledge of newer Freescale devices are very poor, unlike knowledge about the 30 years old ones. I want to keep the Freescale devices, because I just like their architecture, and also migration would be easier.

Performance is not critical, as all modern devices offer more than needed, the only problem is with memory. Currently I need about 9kbytes of RAM and 12kbytes of ROM (FLASH, whatever).

So I took a look at current product line and found... nothing. HC(S)08 lacks RAM and doesn't seem to support external memories, alhough the would offer me everything I need, just the RAM... The only suitable 8-bit MCUs with external bus support are HC11 devices, which seems to be obsolete now and not recommended for new designs.

Maybe I overlooked something, couldn't anybody point me to the right direction, please?

Thanks,

Re: 8-bit with external memory bus

RogerSchaefer — Wed, 25 Mar 2009 03:19:41 GMT

You might look at the 68HC812A4. Technological Arts has several boards with this chip on it.

Also:

If you are interested in the 6809 take a look at the FLEX User Group

http://www.flexusergroup.com/flexusergroup/default.htm

Roger

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