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<DIV><FONT face=Arial size=2>Kev pointed me at the right page on the schematics
(page 163 in the 9100_svc_part2.pdf). Looking at the schems I think this
project just got easier.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I was expecting to have to use a MAX232 (or
similar) TTL (0 - 5v) to RS232 driver chip (+/- 3v). But looking at the
9100 schematic the keyboard signal is just fed to a 74HCT14 / 74LS04 pair which
raise the levels back to TTL. So I think I can just drive this at TTL
levels directly from the microcontroller. Currently looking at one of the small
Atmel parts.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>So this becomes a single chip solution. I
like it.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Anyone want to take a look at the schematic and vet
my answer? Also it looks like though !KBDATA is at pin 1 it just gets fed
to ground so I only need to feed KBDATA.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Now all I need to do is figure out what BAUD rate
the 9100 is expecting its data at.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>David</FONT></DIV></BODY></HTML>
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Received on Mon Jun 02 12:07:31 2003
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