Hi Vlad:

Another option, and the way I like to power 7-segment displays is using
the Allegro 6276.  This is a serial input driver chip that drives 16
pins with a constant current, not multiplex.  These chips can be
connected in series so you can drive any number of digits you want
without using more I/O pins and with great brightness.  You can drive
any color or size LED display very brightly with just a few pins.
See:http://www.pacificsites.com/~brooke/PClock.shtml  The first version
used multiplexing, but with 6 digits the display was not as bright as I
would have liked.  With the 6276 you might consider a brightness
adjustment so you could handle bright sun, normal room light or a dim room.

Have Fun,

Brooke Clarke, N6GCE
http://www.PRC68.com

>Date:    Mon, 9 Feb 2004 15:46:02 -0500
>From:    Vlad <vlad@DOOM.NET>
>Subject: [PIC:] multiplex 7seg LED with drivers
>
>Hello folks,
>
>I'm in the process of designing a toy circuit to keep track of life
>counters for various games.  It should support 3 players.  Each player
>will have two 7 segment LED displays that will display a number between
>0-99, and also 2 switch buttons that will be used to increase and
>decrease the number displayed on these LED displays.
>
>I have a handful of 16f84 PIC's and currently learning how to program
>them.  With only a limited number of input/output pins on this chip
>(13 I believe) what would be a good way to allocate these pins for the
>switch buttons and displays?
>
>I have read various articles in the Usenet archives which suggest
>multiplexing displays, this requires 7 pins for each segment and 1
>pin for every other display.  I think this will eat up in to all my
>pins though.  Can I use the same multiplexing technique with a single
>display/driver chip?  Any suggestions?  Also any thoughts on the switches?
>
>This is my first electronics project and PIC programming project
>(ambitious, yes)
>
>Thanks
>-v
>

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