The current issue of Steve Ciarcia's Circuit Cellar Ink magazine has a
project almost identical to what you are doing, except it converts PC
keyboard make and break codes into RS232.  It is physically tiny, and
designed to fit entirely in the DB9 shell.  Although not exactly what you
are doing, he covers the details of processing PC make/break and scan codes
in depth.

I don't have the issue here at the office, so I can't tell you what MCU he
used, but since this issue is current, you should be able to find it
locally.  The cover of the magazine has an old metal movie film cartridge
on it.  The one with the child's building blocks on it is last month's
issue.


HTH - Martin R. Green
elimar@bigfoot.com

PS. Here's the Circuit Cellar Ink URL:

   http://www.circuitcellar.com/public/cc/ink.html

PPS.  If you use a PIC, you don't need to EEPROM for the conversion tables,
you should be able to use RETLW ROM lookup tables instead.

----------
From:   Steven J Tucker[SMTP:classics@NACS.NET]
Sent:   Thursday, September 18, 1997 2:59 PM
To:     PICLIST@mitvma.mit.edu
Subject:        PIC or SBC?

Hello,

        I recently did a few projects w/ the 16c84 from Microchip, and I
 want to use a PIC to interface an AT keyboard to a computer that uses a
 8x8 matrix keyboard.   To do it I need at least 7 i/o lines for the
matrix,
 2 for the AT keyboard, and enough accessable ram/eprom for a lookup
 table to translate the AT scancodes to the 8x8 matrix.

        I also need some RAM to store the make/break state of the keys, not
 alot but enough to buffer keystrokes as they come in, and remove them
 when lifted.

        What microcontroller should I use?  It would be possible w/ a
 10mhz 16c84 if it had enough EEDATA to store the lookup table, since its
 limited SRAM is probably enough for the buffer.  Is there any way to read
 the program ee area from within the program?  That might make it possible.

        Are there any other PIC's I might consider?   The only one I have
 ever done any projects with so far is the 16c84.

Thanks :)

Steve

    * * *  Author of Imagic and APE - The Atari Peripheral Emulator!  * * *
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