Re: [PARPORT] custom cabling

From: Nate Jenkins (nate@uniwest.com)
Date: Fri Apr 18 2003 - 12:59:23 EDT

  • Next message: Blaise Gassend: "Re: [PARPORT] custom cabling"

    Blaise, et al.

    I appreciate your input. I have tried to not disregard the fact that some
    pins are input and others are output. Maybe my source is questionable...

    http://www.beyondlogic.org/spp/parallel.htm

    Hardware Properties
    .
    .<some copy snipped>
    .
            Pin No (D-Type 25) Pin No (Centronics) SPP Signal Direction In/out
    Register Hardware Inverted
            1 1 nStrobe In/Out Control Yes
            2 2 Data 0 Out Data
            3 3 Data 1 Out Data
            4 4 Data 2 Out Data
            5 5 Data 3 Out Data
            6 6 Data 4 Out Data
            7 7 Data 5 Out Data
            8 8 Data 6 Out Data
            9 9 Data 7 Out Data
            10 10 nAck In Status
            11 11 Busy In Status Yes
            12 12 Paper-Out / Paper-End In Status
            13 13 Select In Status
            14 14 nAuto-Linefeed In/Out Control Yes
            15 32 nError / nFault In Status
            16 31 nInitialize In/Out Control
            17 36 nSelect-Printer / nSelect-In In/Out Control Yes
            18 - 25 19-30 Ground Gnd

      Table 1. Pin Assignments of the D-Type 25 pin Parallel Port Connector.

    Specifically, on nStrobe, I read that it could be used for input or output.
    This is why I thought, it may be fine to connect. Is this not correct?

    I know I have tested with reading and writing to the data/status/control
    ports to see which bits I can use for outputting to the other PC using a
    LapLink cable. I think I double checked my pin assignments before I
    originally sent my inquiry to the list. Am I off? Where I am not certain
    is if I will damage hardware before attempting such a feat.

    Regarding an 8 bit cable, I have only seen the cable at http://www.lpt.com
    for 8 bit transfer. However, they will not even think about allowing their
    products to deviate from the world of M$. I have talked to them a few times
    about Linux support and they inferred that they cannot as if they were being
    watched right then by big brother... I think they have some extra circuitry
    in the cable to buffer and do some crossing over. That is why the cable is
    faster and very software dependent...

    Thank You,

    Nate Jenkins

    United Western Technologies
    Software Engineer
    http://www.uniwest.com

    nate@uniwest.com
    Ph: (509) 544-0720
    Fx: (509) 544-0868

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    ----- Original Message -----
    From: "Blaise Gassend" <blaise@gassend.com>
    To: "Nate Jenkins" <nate@uniwest.com>
    Cc: <linux-parport@torque.net>
    Sent: Thursday, April 17, 2003 4:11 PM
    Subject: Re: [PARPORT] custom cabling

    > > **Proposed Custom Cable Map**
    > > D7 - ~S7 , (09-11) , [data7-busy]
    > > D6 - S6 , (08-10) , [data6-nAck]
    > > D5 - S5 , (07-12) , [data5-paper]
    > > D4 - S4 , (06-13) , [data4-select]
    > > D3 - S3 , (05-15) , [data3-error]
    > > D2 - ~C3 , (04-17) , [data2-nSelPrntr]
    > > D1 - C2 , (03-16) , [data1-nInit]
    > > D0 - ~C1 , (02-14) , [data0-nAutoLF]
    > > ~C0 - ~C0 , (01-01) , [nStrobe-nStrobe]
    >
    > It seems to me like you are disregarding the fact that some pins are
    > inputs and others are outputs. For example, connecting nStrobe to
    > nStrobe won't work because they are both of the same type.
    >
    > I think there are some common designs for 8 bit parallel cables. They
    > connect the data lines to the data lines (on recent parallel ports the
    > data lines are usually bidirectional) and use the unidirectional signals
    > for handshaking. I don't have a link to a precise description of one of
    > these cables, but I expect that a little googling should help. I also
    > expect that the software for these cables is already available.
    >
    > Blaise
    >

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