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I2C through PC parallel port, serial port and/or USB port - please help

Discussion in 'Electronic Basics' started by Adam, Jun 25, 2004.

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  1. Adam

    Adam Guest

    Under Windows NT/2000, I am interested in learning how to
    program an I2C device through the following ports: parallel, serial and USB.

    Is there a reasonably priced good/quality development board with
    I2C device and all the ports mentioned above? Or, any other suggestions?
  2. Gary Tait

    Gary Tait Guest

    For parallel port you don't need one, the interface is dirt simple,
    you can build it into the shell of a d-sub hood.
  3. Bob Masta

    Bob Masta Guest

    However, for NT/2K you will also need to use a kernel-level driver
    in order to gain access to the ports. Check at <>
    for some notes on this. You don't need any special driver
    for Win9x port access.

    Bob Masta

    D A Q A R T A
    Data AcQuisition And Real-Time Analysis
  4. Adam

    Adam Guest

    I'm a newbie so please excuse any dumb questions...

    After your suggestion, I'm thinking about building my own circuitry with
    a solderless breadboard. Hmmm ... would I be able to use a cable to
    connect from the PC's parallel port to the breadboard? If so,
    GREAT but how? It would be nice if I can use my printer cable with
    the breadboard. But, I don't see how with the centronics connectors here: since I don't see how they
    can be used with the breadboard. Am I missing something?
    Or, would I have to get another cable and use the d-sub connectors here: If so, which parts are best to use?
    I need something that will work well with the breadboard.
  5. Adam

    Adam Guest

    Yes, that's what I thought but wasn't sure. Thanks for the confirmation and info.
  6. To get to a breadboard I use this kind:
    Depending on what your breadboard looks like... you straddle the gutter.
    I'd solder into the DB25 or centronix connector.
  7. Adam

    Adam Guest

    This board:
    seems to have many of the features that I am looking for in the target circuit.
    [Am I in over my head? If so, I'll just simplify it.] And,
    they use a DB25M connector to plug directly into
    the PC's parallel port without a cable. I guess I could use a DB25M to
    DB25F extension (or whatchamacallit) cable. Searching
    for "cable db25m db25f" shows two such cables. I only wish that
    there were images or PDFs associated with them. The price is not bad (~$8).

    Or, I could use the more flexible (40-pin) cable that you mention.
    But, I'm not sure I know how best to take advantage of it yet.
    All the choices (single/double ended, gold/tin finish, etc.) is
    confusing for a newbie. Any further suggestions much appreciated.
    Also, I hope to find ways around soldering.
  8. Gary Tait

    Gary Tait Guest

    What I use to ecperiment is a ribbon cble with a 25 pin male, and a 26
    socket pin connector (like is on IDE/floppy ribbon cables).

    Specifically for I2C, I have a reader I built into a hood with a 6 way
    ribbon out with 6 way pin socket.
  9. Adam

    Adam Guest

    I wasn't able to find the ribbon cable with DB25M and 26-pin socket that
    you mention. But, I was able to find a ribbon cable with DB25 M-F (~$5) here:
    Is there a benefit of using the ribbon cable with 26-pin socket?

    Whoa! You're really keeping me on my toes and making (newbie) me think.
    You lost me with the I2C reader and 6-way ribbon cable stuff.
    Further elaboration much appreciated.

  10. On Sat, 26 Jun 2004 18:55:34 -0400, Gary Tait

    He is looking for a good and easy connection to the breadboard. It depends
    a bit on the layout of the breadboard of course but I have found that the
    DIP type plugs work well, they have 0.1 inch X 0.3 inch or even 0.5 inch
    spacing . Like chips .
    What is the pin spacing on the 26pin connector you mention?
  11. Adam

    Adam Guest

    It's not easy to disconnect and connect, IMHO, but
    I guess 0.1" straight male headers like those found here:
    could be used to connect the 26-pin socket connector to the breadboard.

    However, if I cannot find the ribbon cable with the 26-pin socket connector,
    I'll have to go with the ribbon cable with DB25 M-F from: and
    connect the female end to
    a DB25 male right angle PC mount (short type) connector (85-728) from I'm not sure how this
    approach will work with the breadboard though.

    I'm thinking about a solderless breadboard something like:
    Any other suggestions?

    Did you say that the cables with DIP connectors require soldering?
    Is there a way to work around soldering?
  12. Ian Stirling

    Ian Stirling Guest

    There are several linux parallel port drivers supported.
  13. Rich Grise

    Rich Grise Guest

    [crosspost and followups-to trimmed judiciously]

    I've used these things for years, and wouldn't want to live
    without one. You have to be aware of all the stray
    capacitance, and don't plug fat stuff into them, because
    you can distort the little contacts, but I've found that
    #24 wire, like you scrounge from phone trunk cable at
    a construction site, is perfect for those things.
    You can _make_ a cable - we used to do it all the time.

    Cut and paste this: this is a 26-pin IDC female:;524;747;

    You can put one of those on the end of a ribbon cable with
    a little bench vise, and one of these:;524;742;

    on the other end; you can get ribbon cable anywhere,
    then just jumper from the female header to the protoboard
    with little loops of #22 or #24 solid hook-up wire.

    Have Fun!
  14. Si Ballenger

    Si Ballenger Guest

    For simple/test projects, I just use cat3 four conductor
    telephone wire for the parallel port connection. Cheap and easy.
    Below are a couple of projects where I've used the four conductor
    wire. You just use more wires depending on the number of
    conductors you want to use to the parallel port.
  15. The square posts of the male headers are a tight fit for the breadboard
    But the problem IMHO is really that you have to span the 0.3in gap between
    arrays to get all signals to the board.
    The contacts on the board are thus:
    55555__66666 etc.
    If you stick your header into the left column then you connect odd & even
    The DIP type connectors can straddle the gap between columns.

    This may actually work if the right angle pins are long enough & can be
    bent apart to fit the two columns above.
    You'll have to do some bending anyways since the two rows are offset.
    Worth trying.
    This looks rather fancy & way big for what I understand you want to do.
    I have one just like it.
    No. The DIP connector cables I actually bought as readymade harness from
    DigiKey . When the needs changed I cut it apart in the middle & put other
    connectors to those ends.
    I figured if you're only dealing with 6 wires or so it is (for me) quicker
    to solder. If you do 25 wires that is another story.

    BTW if you shop from 3 different suppliers for onesies and twosies the
    shipping & handling cost is going to be brutal.

  16. Gary Tait

    Gary Tait Guest

    Thats becuase I made i t (well, I had a 25 pin Dsub M-M cable I cut
    off the one D-sub and attached the 26 pin connector to).
    The sockets are standard 0.1 inches, and contact the same wire the
    It is a semi custom (home built really), cable I made for programming
    a certain brand of universal remote (One For All).
  17. Gary Tait

    Gary Tait Guest

    Standard 0.1" The same as an IDE or floppy cable, except 26 pins
    instead of 40 or 34 for IDE/Floppy.
  18. Adam

    Adam Guest

  19. Adam

    Adam Guest

    Thanks for the info. I might try making my own cable one of these days.

  20. Adam

    Adam Guest

    Oh, I see your point about DIP type connectors now.

    I think I'm going to make life easier for myself and
    use hookup wires with a female header socket at one end and
    male on the other end similar to the ones mentioned here: under
    "Breadboard and Proto Hookup" to connect the right angle pins to
    the breadboard. Anyone know where I can find these?

    I found larger yet cheaper breadboards here:, and
    Not sure if there are significant differences though.
    Yes, they are big for the current project but
    I might work on bigger projects later.

    You're definitely right about the S&H costs.
    The links were primarily used to make sure that
    we're all on the same page.
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