[PARPORT] 7 switches connected to parport

From: inri (mergrogh@gmx.net)
Date: Mon May 01 2000 - 06:19:08 EDT

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    I am trying to input data using 7 switches connected to the parallel port. I do not know much about elektronics , and i put together a small circuit which does not work correctly. It was based on several parallelport - interfacing howtos i found in the web.
    Three switches are connected to Pins 11, 12, 13 like this :

    pin ---------o-|R 13k|--- +5V
                  o--switch--- +- 0V

    Four switches are connected to Pins 1, 14, 16, 17 :

    pin ---------|out Inverter 74LS05 in|---o--|R 13k|---- +5V
                                             o--switch----- +- 0V

    (I read somewhere that would be useful because these 4 pins are 'open
    collectors' and the 74LS05 would act like a driver ) Now the problem is, that
    the four switches connected over the inverter do not work (they do not
    influence the values i get from inb()). Could anybody help me ? Maybe the 13k
    -Resistors are to strong ? Or am I totally wrong with this circuit ? Please
    excuse my bad english ;)


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