Hello,

    I'm making a PCB for an application that will have 56 LEDs, 24 keys and
and LCD.

    I'm thinking if I could use the same PIC outputs (PORTD on a PIC16F877
or PIC18F452) to the LEDs (anodes via resistors, cathodes have a transistor
switch) and to the display data-bus lines, like the diagram below:

    PICRD0-----+----330R------>|-----------,
               |              LED          |
               '----LCD-DB0                |
                                           |
    PICRD1-----+----330R------>|-----------+
               |              LED          |
               '----LCD-DB0                |
                                           |
    PICRD2-----+----330R------>|-----------+
               |              LED          |
             '----LCD-DB0                  |
                                           |
    PICRD3-----+----330R------>|-----------+
               |              LED          |
               '----LCD-DB0                |
                                           C
                   PICLEDSA---------1k----B
                                           E
                                           |
                                          GND
    etc...

    Obviously, I'll have separate enable and function signal for the LCD on
another PIC pins. The software will have an interrupt to multiplex the LEDs
and send data periodicaly to the LCD.

    There's a catch doing this? Any problems I'm not foreseeing?

    Thank you very much,

    Brusque

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Edson Brusque                 C.I.Tronics Lighting Designers Ltda
Research and Development               Blumenau  -  SC  -  Brazil
Say NO to HTML mail                          www.citronics.com.br
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