F84 has got a full port B and RA0-3
Seven bits for the display and one spare (port B)
RA0 digit 0
RA1 digit 1
Seven buttons on port B
That leaves RA2,3 and RB7 spare you can do an LCD with three wires as
well

Leaves space for three spare pins and up to seven buttons
Crappy ascii sketch


                        E---+5v
RA0,1----R1-----B
                        C
                        |
                        com anode-------internal to other segments
                        |
                        led cathode
                        |
                        R2
RB(x)-------------|
                        R3
                        |
                        sw1
                        |
                        0V

R1 22k base resistor
R2 470R digit resistor
R3 4k7 switch resistor
Transistor PNP any to take led current

Principle
1. set up the digit pattern on port B digit 0
2. make RA0 low
3. make RA0 high
4. make port b inputs
5. read buttons (active low)
6. make port B outputs again
7. set up pattern for digit 1
8. make RA1 low
9. make RA1 high
10. short wait or do sumfing else
11. repeat


Its an idea and works on paper
Regards Steve...

-----Original Message-----
From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU] On Behalf Of Vlad
Sent: 09 February 2004 20:46
To: PICLIST@MITVMA.MIT.EDU
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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