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External timer

homesch00lkidhomesch00lkid Posts: 20
edited 2005-03-28 15:37 in BASIC Stamp
I am trying to do background timing with the BS2, such as running a loop until a minute has passed. I have a PWMPAL, so if I can get something to pulse every second I can count it with that. The PWMPAL itself cannot provide the pulse because I am controlling four motors with it. Any suggestions? It has to be EXTREMELY light weight for my pusposes, and hopefully it won't be too expensive.

Comments

  • Beau SchwabeBeau Schwabe Posts: 6,557
    edited 2005-03-28 02:21
    Is this a one time deal?

    If so, how about hacking a AA battery mechanical clock module? Most hobby craft stores sell these
    as a clock kit for $5 or so.

    Here is a hack that I did ...the module produces one pulse every second with a 1.5V source.
    I realize that you can't see much, but you can get a relative idea of size.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Beau Schwabe - Mask Designer III

    National Semiconductor Corporation
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    Post Edited (Beau Schwabe) : 3/28/2005 2:24:10 AM GMT
    clock.jpg
    355 x 517 - 41K
  • homesch00lkidhomesch00lkid Posts: 20
    edited 2005-03-28 02:59
    That looks like it should work, but I only have 5V and 9V sources available. To regulate 1.5V might make it too heavy. Would it work with higher voltages?
  • Beau SchwabeBeau Schwabe Posts: 6,557
    edited 2005-03-28 03:35
    I just use a voltage divider of 2.2K and 1K to get 1.56V from a 5V supply. Remember the output is only 1.5V but plenty to drive
    the base of an NPN transistor.

    You might still want to explore your options, there are several timer chips to choose from that might be a better solution
    for your application. The clock module hack was just something I did because I had one lying around that had served it's
    purpose as a mechanical clock. I certainly would not spend the $5 on a new clock module just to hack it when timer IC's
    can be purchased for much less.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Beau Schwabe - Mask Designer III

    National Semiconductor Corporation
    Latest Company News
    (Communication Interface Division)
    500 Pinnacle Court, Suite 525
    Mail Stop GA1
    Norcross,GA 30071
  • MacGeek117MacGeek117 Posts: 747
    edited 2005-03-28 15:09
    A 555 would always work.
    bugg

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    Learning Google is your friend: priceless
  • allanlane5allanlane5 Posts: 3,815
    edited 2005-03-28 15:37
    http://www.rhombus-tek.com/co-processors.html

    This guy has a nice 8-pin co-processor which will give you a mostly rock-solid 50 mSec square wave. He has techniques on his web-site to use this square-wave in order to implement a real-time counter on the BS2. You need 8-pins of space for the 8-pin DIP, and a place to plug in the resonator.

    In addition, it gives you an RS-232 recieve port which will buffer up some characters -- but you don't need to use it for that. $11.50, I believe, for a very nice package.
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