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Serial to parallel data controller — Parallax Forums

Serial to parallel data controller

BorisBoris Posts: 81
edited 2004-10-27 00:34 in BASIC Stamp
Lets say I need to control a large number of devices via relays just simple on/off, with a relatively low frequency. And lets say BS2 does not have enough I/O lines. Is there an IC i can use, that will be able to receive info from basic stamp, via one serial line, and convert the data into multiple parallel channels, and hold those pins high or low untill· other data is received from BS2
Something like this:
BS2 feeds 00100111 serial communication, the IC receives the data and sets pins 0,1,2 and 5 high, and pins 3,4,6 and 7 low. When the communication stops the IC will keep its pins set the same way untill further info is received from BS2.

Comments

  • Jon WilliamsJon Williams Posts: 6,491
    edited 2004-10-25 14:37
    I'm not aware of a single wire serial device that does that (the original Scott Edward Stamp Stretcher did -- but it's been long discontinued), but there are plenty of 3-wire (74HC595) and 2-wire (MCP23016) devices that you could use.

    Or ... you could roll your own by programming an SX micro. With the SX28 you could get 19 IO lines; the device has 20 but you need one for serial comm.

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    Jon Williams
    Applications Engineer, Parallax
    Dallas Office
  • allanlane5allanlane5 Posts: 3,815
    edited 2004-10-25 14:43
    What Jon said. The typical way of handling this is with a 74HC595 serial to parallel chip. You connect it with three wires -- Data, Clock, and Chip-Select. Then you talk to it using the SHIFTOUT command.

    Using this approach, you can easily string together more than one 75HC595 to get 16, 24, or 32 bits of output from the same three pins of the Stamp. As I recall, their current drive is pretty high, too, higher than the BS2.
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2004-10-26 01:25
    A little OT, but I just spent the last 1/2 hour searching the forums for a message posted some time ago by someone who said they had an idea for almost unlimited I/O on the Stamp using 3 I/O lines, or something to that effect...But I cannot find the post!· Anyone remember who had the idea?· They were supposed to post their results, but I think it got forgotten about...



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    Chris Savage

    Knight Designs
    324 West Main Street
    P.O. Box 97
    Montour Falls, NY 14865
    (607) 535-6777

    Business Page:·· http://www.knightdesigns.com
    Personal Page:··· http://www.lightlink.com/dream/chris
    Designs Page:··· http://www.lightlink.com/dream/designs
    ·
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2004-10-26 05:30
    Chris -

    Are you sure it wasn't the Microchip MCP23016 16-bit I/O Expander mentioned earilier in this thread. Here is the product link:
    http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1335&dDocName=en010412

    Regards,

    Bruce Bates
  • Jon WilliamsJon Williams Posts: 6,491
    edited 2004-10-26 11:31
    I'm a very big fan of the MCP23016 -- that chip rocks! The interface is I2C, but easy enough to bit-bang with a BS2.

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    Jon Williams
    Applications Engineer, Parallax
    Dallas Office
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2004-10-26 15:29
    No, a member of these forums said he'd come up with an idea for this simple, yet elaborate method of expanding the outputs of the BS2 in certain increments.· The words unlimited were used I think.

    Jon Williams replied saying that eventually he'd run out of variable space for data to send out.

    Then myself, followed by Sid said we'd be interested in hearing his theory.· But I don't recall anything ever being posted again, nor can I find the original thread to see who it was...



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    Chris Savage

    Knight Designs
    324 West Main Street
    P.O. Box 97
    Montour Falls, NY 14865
    (607) 535-6777

    Business Page:·· http://www.knightdesigns.com
    Personal Page:··· http://www.lightlink.com/dream/chris
    Designs Page:··· http://www.lightlink.com/dream/designs
    ·
  • southernbobsouthernbob Posts: 34
    edited 2004-10-26 17:09
    Try this thread near the bottom.

    http://forums.parallax.com/showthread.php?p=468086
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2004-10-26 20:39
    AH YES!· Thank you SouthernBob!· It was driving me absolutely bonkers trying to find that!· Now we just gotta get ahold of Gerry Shand·and see if he ever came up with anything!

    confused.gif

    Gerry?

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    Chris Savage

    Knight Designs
    324 West Main Street
    P.O. Box 97
    Montour Falls, NY 14865
    (607) 535-6777

    Business Page:·· http://www.knightdesigns.com
    Personal Page:··· http://www.lightlink.com/dream/chris
    Designs Page:··· http://www.lightlink.com/dream/designs
    ·
  • southernbobsouthernbob Posts: 34
    edited 2004-10-26 21:37
    Hi Chris,
    Glad to help, to keep you from going 'bonkers'.· The way I found it was
    to do a search on your name·and 'posted by' selection. Then I looked at the
    returned snippets ·to see likely possibilites. Since you are a prolific
    appender, I had to look at 200 messages and go back 2 months.
    Bob
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2004-10-27 00:34
    southernbob said...(trimmed)
    Since you are a prolific appender, I had to look at 200 messages and go back 2 months.
    Bob
    ROFLOL!· I have never been called that before!· Hehehe A prolific appender...LOL· That almost makes me feel like a repeat offender!· smilewinkgrin.gif

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    Chris Savage

    Knight Designs
    324 West Main Street
    P.O. Box 97
    Montour Falls, NY 14865
    (607) 535-6777

    Business Page:·· http://www.knightdesigns.com
    Personal Page:··· http://www.lightlink.com/dream/chris
    Designs Page:··· http://www.lightlink.com/dream/designs
    ·
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