RE: The need to individually switch 50 LED's

["Ward, David" <DAvid.Ward@xxxxxxxxxx>]

A few suggestions that I know work

First is to use an embedded micro (e.g. a 12c series PIC, small 8 pin job)
and use a simple serial protocol to address LEDs hung off of it's output
port. Run 2 wires around for power and another wire for serial comms. If
you
can accept a little more 'electronics' then you could also superimpose the
data on the power line
Have a look at the model train Digital control stuff.  I have a colleague
here who has made controllers and train modules that allow independent
control of train speed direction lighting and Power all from just two wires
(The train tracks) It is apparently a fully documented open standard.

Second is to use Dallas 1-wire devices. The DS2407 is a dual addressable
switch IC  will give you a ready made 'one wire' LED control.  Couple that
with freely available code from maxim/Dallas and a USB to 1-wire or RS232
to
1-wire converter for the controlling PC

Thirdly how about a few simple serial to parallel shift registers.  These
can be found with built in drivers, so can drive LEDs directly, just daisy
chain the lot together and load the registers by bit banging data out of a
serial or parallel port on the PC

Hope this is of some use to get you started.
(I'm sure others will come up with better ideas)

Dave


-----Original Message-----
From: groups@xxxxxxx [mailto:groups@xxxxxxx]
Sent: 31 March 2004 20:30
To: ukha_d@xxxxxxx
Subject: [ukha_d] The need to individually switch 50 LED's


Hi Group

I have a need to individually switch 50 LED's from a PC - can anyone
recommend anything and how to do it?

I am ofay with soldering, writing code etc, can anyone recommend an
interface method?

For those of you who are just wondering why? I have a display cabinet with
50 ornaments and want to individually light them on user selection and via
a
script (sad huh?) Thus the wire has to be discreet as well as the LED's
shining on each ornament.

Cheers

J




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