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<div class=Section1>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Hi laurie,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:navy;mso-ansi-language:EN-GB'>Thanks
for your email! I checked those parts on <span class=SpellE>digikey</span> and
they are all obsolete. I’d also like to be able to adjust brightness <o:p></o:p></span></font></p>
<p class=MsoNormal><span class=GramE><font size=2 color=navy face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial;color:navy;mso-ansi-language:
EN-GB'>through</span></font></span><font size=2 color=navy face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial;color:navy;mso-ansi-language:
EN-GB'> PWM … <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:navy;mso-ansi-language:EN-GB'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:navy;mso-ansi-language:EN-GB'>I’m
actually not sure what will happen if I try to do PWM on the <span
class=SpellE>LEDs</span> from my MCU and the MCU gets interrupted now and <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:navy;mso-ansi-language:EN-GB'>Then
by the UART for </span></font><st1:place><font size=2 color=navy face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial;color:navy;mso-ansi-language:
EN-GB'>MIDI</span></font></st1:place><font size=2 color=navy face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial;color:navy;mso-ansi-language:
EN-GB'> communications<span class=GramE>… ?</span><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:navy;mso-ansi-language:EN-GB'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:navy;mso-ansi-language:EN-GB'>Thanks,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:navy;mso-ansi-language:EN-GB'><o:p> </o:p></span></font></p>
<p class=MsoNormal><span class=SpellE><span class=GramE><font size=2
color=navy face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:
Arial;color:navy;mso-ansi-language:EN-GB'>bert</span></font></span></span><font
size=2 color=navy face=Arial><span lang=EN-GB style='font-size:10.0pt;
font-family:Arial;color:navy;mso-ansi-language:EN-GB'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:navy;mso-ansi-language:EN-GB'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='margin-left:35.4pt'><font size=2 face=Tahoma><span
lang=EN-US style='font-size:10.0pt;font-family:Tahoma;mso-ansi-language:EN-US'>-----Original
Message-----<br>
<b><span style='font-weight:bold'>From:</span></b> Elby Designs
[mailto:elby_designs@ozemail.com.au<span class=GramE>] <br>
<b><span style='font-weight:bold'>Sent</span></b></span><b><span
style='font-weight:bold'>:</span></b> vrijdag 11 juli 2003 9:55<br>
<b><span style='font-weight:bold'>To:</span></b> Bert Schiettecatte<br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: [sdiy] I/O trouble...</span></font></p>
<p class=MsoNormal style='margin-left:35.4pt'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'><o:p> </o:p></span></font></p>
<div>
<p class=MsoNormal style='margin-left:35.4pt'><font size=3 face=Arial><span
style='font-size:12.0pt;font-family:Arial'>The MM5484 (there are others that
are similar) is a 16-segment LED driver that uses Nationals MicroWire for
communications. That is a 3-wire communications path for 16-segments and
4-wires for 32 segments.</span></font><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal style='margin-left:35.4pt'><font size=3 face=Arial><span
style='font-size:12.0pt;font-family:Arial'>Also check out there MM5450 and
MM5451 chips.</span></font><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal style='margin-left:35.4pt'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'><br>
Best Regards<br>
Laurie Biddulph<br>
<a href="http://www.ozemail.com.au/~boobies">http://www.ozemail.com.au/~boobies</a><br>
Mobile: 0404 846 943<o:p></o:p></span></font></p>
</div>
<blockquote style='border:none;border-left:solid black 1.5pt;padding:0cm 0cm 0cm 4.0pt;
margin-left:3.75pt;margin-top:5.0pt;margin-right:0cm;margin-bottom:5.0pt'>
<div>
<p class=MsoNormal style='margin-left:35.4pt'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>----- Original Message ----- <o:p></o:p></span></font></p>
</div>
<div style='font-color:black'>
<p class=MsoNormal style='margin-left:35.4pt;background:#E4E4E4'><b><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial;font-weight:
bold'>From:</span></font></b><font size=2 face=Arial><span style='font-size:
10.0pt;font-family:Arial'> <a
href="mailto:bert.schiettecatte@esat.kuleuven.ac.be"
title="bert.schiettecatte@esat.kuleuven.ac.be">Bert Schiettecatte</a> <o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='margin-left:35.4pt'><b><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial;font-weight:bold'>To:</span></font></b><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'> <a
href="mailto:synth-diy@dropmix.xs4all.nl" title="synth-diy@dropmix.xs4all.nl">synth-diy@dropmix.xs4all.nl</a>
<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='margin-left:35.4pt'><b><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial;font-weight:bold'>Sent:</span></font></b><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'> Friday,
July 11, 2003 9:09 AM<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='margin-left:35.4pt'><b><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial;font-weight:bold'>Subject:</span></font></b><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'> [sdiy] I/O
trouble...<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='margin-left:35.4pt'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'><o:p> </o:p></span></font></p>
</div>
<p class=MsoNormal style='margin-left:35.4pt'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>Hi All,<o:p></o:p></span></font></p>
<p class=MsoNormal style='margin-left:35.4pt'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='margin-left:35.4pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial;mso-ansi-language:EN-GB'>On
my daily adventures with microcontrollers I am faced with another I/O problem.
Please forgive me my silly questions since I’m not an electronics expert.
<o:p></o:p></span></font></p>
<p class=MsoNormal style='margin-left:35.4pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial;mso-ansi-language:EN-GB'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='margin-left:35.4pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial;mso-ansi-language:EN-GB'>Here
goes:<o:p></o:p></span></font></p>
<p class=MsoNormal style='margin-left:35.4pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial;mso-ansi-language:EN-GB'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='margin-left:35.4pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial;mso-ansi-language:EN-GB'>I
have a MCU with 2 8-bit ports available, one of them is the A/D. Since
I’m connecting an LCD to the MCU as well, I need one port as the
LCD’s data bus. <o:p></o:p></span></font></p>
<p class=MsoNormal style='margin-left:35.4pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial;mso-ansi-language:EN-GB'>So
that leaves me without any pins to light my LED matrix (32 leds = 4x8) and scan
my key matrix (up to 32 keys). <o:p></o:p></span></font></p>
<p class=MsoNormal style='margin-left:35.4pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial;mso-ansi-language:EN-GB'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='margin-left:35.4pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial;mso-ansi-language:EN-GB'>I
thought about putting an SN74CBT16233 on the 2 8-bit ports, this will give me
another 16 I/O lines. This IC is a 16-bit 1-of-2 FET multiplexer. So I would <o:p></o:p></span></font></p>
<p class=MsoNormal style='margin-left:35.4pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial;mso-ansi-language:EN-GB'>put
the A/D and LCD data bus on one output of the multiplexer and the key matrix +
led matrix on the other output of the multiplexer. The key and led matrix <o:p></o:p></span></font></p>
<p class=MsoNormal style='margin-left:35.4pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial;mso-ansi-language:EN-GB'>would
be 8 rows which I want to put power on sequentially, and then use 4 columns to
light the LEDs and 4 columns to scan the keys. Does this make <o:p></o:p></span></font></p>
<p class=MsoNormal style='margin-left:35.4pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial;mso-ansi-language:EN-GB'>any
sense? I’m just trying to find a way to hook up all this I/O. Argh! <o:p></o:p></span></font></p>
<p class=MsoNormal style='margin-left:35.4pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial;mso-ansi-language:EN-GB'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='margin-left:35.4pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial;mso-ansi-language:EN-GB'>It’s
ok if I lose some brightness by multiplexing, as long as they have a decent
visibility I’m happy. I’m also concerned that the MCU might go to
heaven if I <o:p></o:p></span></font></p>
<p class=MsoNormal style='margin-left:35.4pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial;mso-ansi-language:EN-GB'>make
it source and sink the current for the LEDs (even when only one LED gets lit at
a time for a very short period). <o:p></o:p></span></font></p>
<p class=MsoNormal style='margin-left:35.4pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial;mso-ansi-language:EN-GB'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='margin-left:35.4pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial;mso-ansi-language:EN-GB'>Thanks
for any suggestions…<o:p></o:p></span></font></p>
<p class=MsoNormal style='margin-left:35.4pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial;mso-ansi-language:EN-GB'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='margin-left:35.4pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial;mso-ansi-language:EN-GB'>Bert
(very tired and going to bed now)<o:p></o:p></span></font></p>
<p class=MsoNormal style='margin-left:35.4pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial;mso-ansi-language:EN-GB'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='margin-left:35.4pt'><font size=2 face=Arial><span
lang=EN-GB style='font-size:10.0pt;font-family:Arial;mso-ansi-language:EN-GB'><o:p> </o:p></span></font></p>
</blockquote>
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