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BS2 pins connected to other BS2 pins — Parallax Forums

BS2 pins connected to other BS2 pins

ArchiverArchiver Posts: 46,084
edited 2001-12-28 21:45 in General Discussion
Hi,

I would like to know if it is safe to connect the IO pins of one
stamp to the IO pins of another stamp. Can one stamp sink everything
another can source. Or do I need a resistor in between them

I need to do some very mild comunication between two BS2's.

my email is stuff@m...

Happy Holidays to all,

Rod

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2001-12-28 21:34
    Technically you don't need resistors IF you have only one output pin at
    a time. However, it would be prudent to put a small resistor between
    each pin in case you accidentally made both outputs of different values
    at one time. A 1K resistor would be OK and would cause 5mA to flow in an
    error state -- not much at all. The only downside is that if you use
    long wires the increased R and C could stretch signals. For moderately
    short runs you won't have any problem at all.

    Al Williams
    AWC
    * Floating point A/D
    http://www.al-williams.com/awce/pak9.htm



    >
    Original Message
    > From: bru2seismo [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=7AHSrNSqE42xLcJGl6zVYKny6T7bcXFL-iocA3gNnKRbct6Rz3jdnDqDcOIqX1eg0Dfv-EXF59KR3cQM2QMcrQ]stuff@m...[/url
    > Sent: Friday, December 28, 2001 3:26 PM
    > To: basicstamps@yahoogroups.com
    > Subject: [noparse][[/noparse]basicstamps] BS2 pins connected to other BS2 pins
    >
    >
    > Hi,
    >
    > I would like to know if it is safe to connect the IO pins of one
    > stamp to the IO pins of another stamp. Can one stamp sink everything
    > another can source. Or do I need a resistor in between them
    >
    > I need to do some very mild comunication between two BS2's.
    >
    > my email is stuff@m...
    >
    > Happy Holidays to all,
    >
    > Rod
    >
    >
    > To UNSUBSCRIBE, just send mail to:
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    >
  • ArchiverArchiver Posts: 46,084
    edited 2001-12-28 21:34
    It is always a good idea to use a resistor between IO of one stamp and IO of
    another this is in case they both wind up as outputs in opposite states.
    Anything from 470 ohm to 10K is common, and even 100K will work in most
    cases.
    Original Message
    From: "bru2seismo"
    > Hi,
    >
    > I would like to know if it is safe to connect the IO pins of one
    > stamp to the IO pins of another stamp. Can one stamp sink everything
    > another can source. Or do I need a resistor in between them
    >
    > I need to do some very mild comunication between two BS2's.
    >
    > my email is stuff@m...
    >
    > Happy Holidays to all,
    >
    > Rod
  • ArchiverArchiver Posts: 46,084
    edited 2001-12-28 21:45
    While training European electronics instructors in BASIC Stamp programming
    and applications this past summer, I often referred to resistors as "cheap
    insurance." Even though I have a lot of experience with Stamps (7 years) and
    don't have to pay for them ... whenever I connect two Stamp pins together I
    put a resistor in between (usually 1 kOhm). It's better to be safe than
    sorry.

    Watch for the January 2002 issue of Nuts & Volts magazine. My column ("Stamp
    Applications") discusses connecting Stamp pins and synchronized
    communications between two Stamps.

    Happy New Year.

    -- Jon Williams
    -- Parallax



    In a message dated 12/28/01 3:27:27 PM Central Standard Time,
    stuff@m... writes:


    > I would like to know if it is safe to connect the IO pins of one
    > stamp to the IO pins of another stamp. Can one stamp sink everything
    > another can source. Or do I need a resistor in between them
    >
    > I need to do some very mild comunication between two BS2's.
    >







    [noparse][[/noparse]Non-text portions of this message have been removed]
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