Re: [PARPORT] Reading from pin - help.

From: Blaise Gassend (
Date: Thu Dec 19 2002 - 22:53:46 EST

  • Next message: Jeffery Tyree: "Re: [PARPORT] Reading from pin - help."


    In all the messages you have sent, you have finally specified the
    CRUCIAL piece of information:

    You are trying to interface with a dallas 1820 temperature sensor. THIS
    allows us to understand what you are up to. How could we possibly hawe
    guessed from your question that you were trying to read anything more
    than the state of a switch. For next time, I really suggest that you
    take the time to specify precisely what you are doing. More people will
    take the time to help you, and they will take less time doing so that

    It turns out that the dallas 1820 has a rather elaborate communication
    protocol that is designed to make the wiring as simple as possible. The
    result is that the software needed to support it is concequently much
    more elaborate.

    I would suggest the following references:

    The datasheet :

    This page that claims to have linux code to do just what you want over
    the serial port, I haven't checked more in detail than that :

    From what I have gathered from a brief look at the DS1820, you would
    actually need to use an output pin of your parallel port in addition to
    the input pin you are currently using.

    Blaise Gassend

    Quoted from Pawel Stochlinski on Fri, Dec 20, 2002 at 12:57:47AM +0100.
    > The program idea is to read a data from dallas 1820 temperature sensor that
    > is connected to the PIN 10 (ACK) of LPT port.
    > All i want to do, is to use a simple, quick code that will read the pin 10.
    > All i have red about reading paraller ports is to use:
    > x=inb(STATUS); (for statusports)
    > Hey, but this is not all! I want to read a BYTES from pin 10, not a state of
    > ALL pins in statusport.
    > Please, tell me, how can i read ONE pin (for example pin nr. 10[ACK]), isnt
    > there any quick, simple method?

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