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'[OT] 7 segment multiplexed digits'
2000\02\06@222936 by Lorick

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I ended up with a dual digit module of  a 7 segment display from Digikey
(part 67-1421-ND)
and it's got multiplexed pins.

Is there a general scheme for figuring out the data control lines on this or
otherwise how can I learn to use it?  I don't know the manufacturer off hand
to look up spec sheets so I was wondering if someone offhand knew how to use
multiplexed led displays.

Right now I don't know what any of the pins do.  Don't even know where the
common connection is.

2000\02\07@102630 by wagner

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This is a COMMON CATODE (ground) green unit. LDD-C402NI from Lumex.
Take a look at the pdf file:

http://www.lumex.com/cgi-bin/pdf_filter.pl?1000132.PDF

This unit is *not* multiplexed, to do it you need to connect same
segment pins together, as pin 15 to 10, 13 to 12 and so on (see
picture), exception to pins 4 and 5 that is the common catode pis, those
two pins would be your "select digit" connected to two transistors to
ground, and your pic would select which digit would lite.

Common catode units are not the "best" to multiplex with a PIC, since
the display will need "positive" level drive at the segments, while
microcontrollers have the great ability to sink more current than drive
it.

Wagner.

Lorick wrote:
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2000\02\07@105819 by jkitchen

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I have a similar problem....  4 digit, 7 segment LDC display from Jameco (Item
17110).  No data, no brand on it, no makings anywhere -- nothing but the pretty
LCD display and it's 40 pins....   If you find anything, please let me know
too.  TIA

Lorick wrote:

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