[sdiy] I/O trouble...

[phillip m gallo]

You might want to take a look at this Maxim product page.

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, July 11, 2003 1:36 AM
To: synth-diy at dropmix.xs4all.nl
Subject: RE: [sdiy] I/O trouble...


Hi laurie,



Thanks for your email! I checked those parts on digikey and they are all
obsolete. I’d also like to be able to adjust brightness

through PWM …



I’m actually not sure what will happen if I try to do PWM on the LEDs from
my MCU and the MCU gets interrupted now and

Then by the UART for MIDI communications… ?



Thanks,



bert



-----Original Message-----
From: Elby Designs [mailto:elby_designs at ozemail.com.au]
Sent: vrijdag 11 juli 2003 9:55
To: Bert Schiettecatte
Subject: Re: [sdiy] I/O trouble...



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.

Also check out there MM5450 and MM5451 chips.


Best Regards
Laurie Biddulph
http://www.ozemail.com.au/~boobies
Mobile: 0404 846 943

  ----- Original Message -----

  From: Bert Schiettecatte

  To: synth-diy at dropmix.xs4all.nl

  Sent: Friday, July 11, 2003 9:09 AM

  Subject: [sdiy] I/O trouble...



  Hi All,



  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.



  Here goes:



  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.

  So that leaves me without any pins to light my LED matrix (32 leds = 4x8)
and scan my key matrix (up to 32 keys).



  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

  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

  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

  any sense? I’m just trying to find a way to hook up all this I/O. Argh!



  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

  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).



  Thanks for any suggestions…



  Bert (very tired and going to bed now)





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