[sdiy] mcu project with too few I/O lines :(

[Bert Schiettecatte]

thanks all for the suggestions! 

after thinking about the additional software / hardware complexity 
all these solutions would couse, I think I'll go for the ATMEGA32 
instead of all this. it gives me more I/O and I'll probably need 
the memory too because of the graphical LCD ...

turns out that I can fit all I/O nicely onto the available I/O lines
of the ATMEL. I'll only have to share one 8 bit port between the ADC 
and a 16 key matrix, but I guess that's not too bad. 

bert

-----Original Message-----
From: phillip m gallo [mailto:philgallo at attglobal.net]
Sent: vrijdag 23 mei 2003 22:14
To: Bert Schiettecatte
Cc: synth diy
Subject: RE: [sdiy] mcu project with too few I/O lines :(


Bert,

You might evaluate the 74HC595 as they allow simple serial to parallel
interfacing.

regards,
p

-----Original Message-----
From: owner-synth-diy at dropmix.xs4all.nl
[mailto:owner-synth-diy at dropmix.xs4all.nl]On Behalf Of Bert
Schiettecatte
Sent: Friday, May 23, 2003 11:24 AM
To: synth-diy at dropmix.xs4all.nl
Subject: [sdiy] mcu project with too few I/O lines :(


hi all,

i'm doing a microcontroller project here with an optrex graphical
display (128x64), rotary encoder, led matrix (16 leds), and key
matrix (16 keys). of course there is also the midi and in system
programming connectors. unfortunately my microcontroller (atmega8)
does not have a lot of i/o lines available, and I'm left clueless
how to interface all that stuff to it. The display has an 8bit
data bus + a few i/o lines for reading, writing, etc. for the
led matrix, i'd like brightness control for each led (PWM?).

I thought about using a key encoder and maybe an LED driver but
those ICs are pretty expensive (7$ for a key encoder, that's more
than a microcontroller!). does anyone have some advice here and
how to interface this stuff without buying tons of additional ICs
which cost a lot of $$$?

thanks,
bert
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