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Advice Please: LCD Timer Project

Discussion in 'Electronic Basics' started by Darren Harris, Oct 20, 2004.

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  1. I need what will basically be a digital stopwatch. It will need to be
    an accurate LCD timer/clock that can record a huge number of splits to
    1/60th of a second, and since nothing like what I need is on the
    market I'll obviously have to build one for myself, if this is
    possible.

    This may be a simple project, or a really complex one. But I was
    hoping to get ideas on where/how to start.

    Outisde of it's foot-print not being more than about 2 or 3 inches
    wide, the following is what I'm after...

    1) Two digital displays:
    A) One for the main timer, which can be reset to zero at the press of
    a button.
    B) One that will show the latest split time, at the press of a button.

    2) The ability to record/recall *at least* 256 splits.

    Any advice on what parts and where to get them would be greatly
    appreciated.

    Thanks a lot.

    Darren Harris
    Staten Island, New York.
     
  2. jakdedert

    jakdedert Guest

    I think I'd look into whatever stopwatch programs are available for handheld
    PDA's. There are some good deals out there for monochrome Palm OS devices.
    (In fact, I'd unload one of mine to the right buyer.) It seems that I've
    seen programs which might do what you desire. Certainly there are stopwatch
    programs out there. Do a Google search....

    Much easier to program a computer (PDA) to do the above, than to build a
    dedicated hardware solution....

    jak
     
  3. John

    John Guest

    I'll second the PDA platform. Monochrome Palm devices have recently
    been available for $30US at Fry's, Sears, Ebay, computergeeks.com,
    surpluscomputers.net, and others.

    Most of these devices have a hardware clock with 100 clock
    ticks/second, so you can can get fractional seconds - however, 1/60
    second doesn't divide well with 1/100 second pulses ;-)
     
  4. I bet the 1/60th probably came from the power line and they'd actually prefer
    1/100th accuracy!

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  5. NSM

    NSM Guest

    | I need what will basically be a digital stopwatch. It will need to be
    | an accurate LCD timer/clock that can record a huge number of splits to
    | 1/60th of a second, and since nothing like what I need is on the
    | market I'll obviously have to build one for myself, if this is
    | possible.

    Not sure how many 'huge' is, but an old Model 100 Radio Shack computer will
    do it. There's a M/L program you can download to give you several splits.

    N
     
  6. jakdedert

    jakdedert Guest

    A model 100 (I remember mine fondly...) doesn't really fit his size
    criterea...PDA's much more available, with current program development. My
    guess is that the program is available in shareware. There's an immense
    amount of resources available. If an available program doesn't exactly fit
    his needs, he could either modify the criterea, or possibly convince the
    programmer to develop a modification.

    jak
     
  7. I know nothing at all about PDAs or programming. But from what I can
    tell, it wouldn't suit my purpose anyway. I was visualizing two
    displays(like the big red numbers on those easy to read digital
    clocks). For power consumption reasons I assumed that this timer would
    have to be something I'd plug into an outlet. I could settle for a
    timer that would increment at 1/100th of a second instead of 1/60th.
    So I guess that would mean that I'd need 8 decimal places for the
    display that would show the split times.

    Anyway, from what I gather, what I want to do is too complicated,
    going by the recommdations so far.

    Or perhaps there is a way to use a PDA hidden in a specially built box
    where it would output to the kind of displays I need. Is this
    plausible?

    Thanks a lot.

    Darren Harris
    Staten Island, New York.
     
  8. Rich Grise

    Rich Grise Guest

    Oh, that's only because everybody jumped on that pocket thing.
    All you need is a clock oscillator, a counter, a few latches
    and display drivers, and some gating logic.

    You push "start", that gates on the counter (so you get a full cycle
    at start time - the oscillator is free-running), and then your "time 1"
    button latches the current count into display 1, your "time 2" button
    latches display 2, and so on. You can add displays all day long, if you
    want.

    Maybe a dozen parts, if you do it all with "discrete" chips.
    Yabbut, it's way overkill, or maybe "underkill." ;-) Like I said, you can
    do it with a few counters and latches. For a digital weenie like me, it's
    just a matter of connecting the dots. :)

    Chips you might want to look at:
    74HC393 - dual decade counter
    74HC273 - 8-bit D FF (or edge-triggered latch)

    Oh, yeah, you'll need some kind of BCD-to-7-segment decoders, but you
    already knew that, right? ;-)

    Have Fun!
    Rich
     
  9. jakdedert

    jakdedert Guest

    Fun, I guess, but: <http://www.intellitimer.com/>
    Sport's #1 Stopwatch Software
    for Palm OS handhelds and compatibles
    Intelli-products are now used in over 100 countries worldwide!

    Times, Totals, & Tabulates

    ....splits, finishes, and speeds for all sports!

    IntelliTimer:
    * Tri-Timer display;
    * Delta Time Tracking;
    * Multi-mode operation;
    * Unlimited event logging;
    * 50 split/finish times per event;
    * Accuracy to 1/100th second;
    * Event timing up to 99 hours;
    * Finish-time and group editing;

    * Editable descriptions and events;
    * Real-time split display and recording;
    * Editable descriptions and events;
    * Beaming to other Palm-enabled handhelds;
    * PC Desktop Companion;;
    * Print results;
    * Save results to Web page;
    * Save results to CSV file;
    * Create charts
    IntelliTimer: For the timings of your life!

    or maybe: http://www.palmspot.com/software/detail/ps4238a_98332.html:
    Banana Split Race Timer 2.0a
    Race Split Timer
    SHAREWARE- $25.00
    from: Medical Informatics, Inc.
    Complete race timer which can be used for recording race results or on the
    course to record splits. Keeps track of laps, interval starts, multiple
    classes of racers, race groups (teams), racer names.

    Was originally designed as a XC ski race timer to track complex splits and
    interval starts for on-course coaching. Gives lap information, time from
    leader, time to next racer and much more.

    Racer registration screen allows you to enter names, classes, groups, and
    start delay for each racer.

    Full reporting on screen and export to memo pad.

    Improved split time display and performance of the program.
    You can now operate program with one hand!
    Instant Split display gives you everything you need to know.
    Now can also sort and display results by lap and class.

    If neither of these work, you can try:
    http://www.palmspot.com/software/detail/ps2908a_98332.html
    PocketTimer 2.1

    COMMERCIAL- $49.95
    from: Stevens Creek Software
    The handheld, inexpensive race timing solution, ideal for race directors,
    running clubs, or anyone else putting on an event that needs timing. Use it
    as primary finish line timing or as backup for existing timing gear. Record
    transition times in triathlons, split times at aid stations in an ultra, or
    anything else. Records bib#, place, time, and pace for thousands of racers.
    Download the results to your desktop computer in an easy-to-read format.

    - What's New! -----
    New updates in this version:
    Times can be sorted by time or bib#
    export of data is controlled so user can specify place
    bib#, time, and/or pace to be exported in CSV or tab-delimited format.

    Or you might want to try:
    http://www.palmspot.com/software/detail/ps1721a_98332.html
    RaceTimes 1.2

    SHAREWARE- $15.00
    from: Nu-Log Pty Limited
    This program records times (up to 100) in hh:mm:ss using the hard buttons on
    the PalmPilot. Names (or numbers/boats) are recorded using graffiti (or the
    popup keyboard). A clock can be displayed on screen in either 12 or 24 hour
    mode. The PalmPilot may be turned off, and when the "Record" button is
    pressed, the time is recorded (and the Pilot turns on). The program was
    originally written to record sailing results, but is equally useful for any
    race or purpose where times need to be recorded to 1 second accuracy. More
    than one time can be recorded for the same second.


    Now you can output to the Serial Port. So you can Print to a Serial Printer
    (or Parallel Printer using a converter) or capture to a File (or print to
    your computer's printer) on a Computer using a Terminal program (does not
    require HotSync software)
    RaceTimes 1.2

    or: http://www.palmspot.com/software/detail/ps653a_98332.html
    or: http://www.a-metrics.com/laptrack1.htm
    or maybe something from here:
    http://www.pilotzone.com/palm/util_time_pop.html

    Those are just from a quick search on Google for "Palm stopwatch program"
    There are many more....

    jak
     
  10. Okay.

    Since there doesn't seem to be another way, can anyone refer me to
    someone who may be able to build something like what I'm after?

    Thanks.

    Darren Harris
    Staten Island, New York.
     
  11. John Fields

    John Fields Guest

     
  12. hamilton

    hamilton Guest

    "2.com" is not a valid email.
     
  13. Rich Grise

    Rich Grise Guest

    Apparently not just plain multiple displays, each with its own
    "latch" button, all started and clocked together.

    Cheers!
    Rich
     
  14. What's a "split"?
    Splits = individual lap times.

    I'll settle for a single LCD display if I have to.

    Since this appears to be too complicated, perhaps I can start off with
    something simple. Does anyone know how to build a simple timer with an
    LCD screen that shows hours, minutes, and seconds?

    Thanks.

    Darren Harris
    Staten Island, New York.
     
  15. James Sweet

    James Sweet Guest

    It's not terribly complicated, but either way you'll pretty much need to use
    a microcontroller. Check out www.maximic.com for LCD display driver chips,
    and look at www.atmel.com or www.microchip.com for microcontroller info. You
    could save some hardware time by using a ready-made LCD display, 16
    character x 2 line displays are relatively common, cheap, and not overly
    complex to drive. To save some time coding you can skip the assembly
    language and look into one of the compilers out there, RVK Basic, Bascom
    Basic, PICBasic, C, etc. Another advantage of this approach is that if you
    don't like the way it works or think of a new feature you want, you simply
    tweak the code until it works the way you want it to.
     
  16. It's not terribly complicated, but either way you'll pretty much need to use
    Unfortunately, since I know nothing about microcontrollers, driver
    chips, or programming, can anyone advise me on how I can find someone
    who could do this?

    Thanks.

    Darren Harris
    Staten Island, New York.
     
  17. Unfortunately, driving an LCD screen isn't a simple thing; they are
    really designed to be driven using software. There may be front-end
    chips which simplify them, but LED 7-Segment displays are much easier to
    drive from discrete logic.

    Building a 'simple' timer with discrete, digital logic isn't as easy as
    it seems. You need

    1) a timer source, like an oscillator circuit
    2) a counter (or more like a set of counter chips)
    3) logic to sample these counter outputs, and display the results on an
    the LED segments.

    At the least, this will require

    1) a crystal oscillator/divider, like the philips hef4521b combination
    oscillator/divider chip. Using a crystal, you can generate accurate one
    second clock pulses

    2) a set of bcd counters, one per decade of timing accuracy.
    3) a set of LED 7-segment display drivers, one per digit.
    4) some 7 segment displays
    5) power supply
    6) enclosure

    You can get fancy and multiplex the LED displays, thus cutting down on
    the number of chips required, but this increases the complexity a bit,
    requiring more logic.

    Note that a microcontroller costing less than a buck can replace 1-3
    with a simple program of about 100 lines of assembler. Also, there are
    designs for discrete timer circuits out on the web, if you want to look
    and see what you are getting yourself into before starting.

    If you decide to try to show speeds, you'll need division as well, which
    is fairly easy in a microcontroller, and much harder with digital logic.

    --
    Regards,
    Robert Monsen

    "Your Highness, I have no need of this hypothesis."
    - Pierre Laplace (1749-1827), to Napoleon,
    on why his works on celestial mechanics make no mention of God.
     
  18. James Sweet

    James Sweet Guest


    I didn't either until a couple years ago, it was having an achievable goal
    like this that gave me the motivation and direction to learn it.
     
  19. NSM

    NSM Guest

    | > It's not terribly complicated, but either way you'll pretty much need to
    use
    | > a microcontroller. Check out www.maximic.com for LCD display driver
    chips,
    | > and look at www.atmel.com or www.microchip.com for microcontroller info.
    You
    | > could save some hardware time by using a ready-made LCD display, 16
    | > character x 2 line displays are relatively common, cheap, and not overly
    | > complex to drive. To save some time coding you can skip the assembly
    | > language and look into one of the compilers out there, RVK Basic, Bascom
    | > Basic, PICBasic, C, etc. Another advantage of this approach is that if
    you
    | > don't like the way it works or think of a new feature you want, you
    simply
    | > tweak the code until it works the way you want it to.
    |
    | Unfortunately, since I know nothing about microcontrollers, driver
    | chips, or programming, can anyone advise me on how I can find someone
    | who could do this?

    If you look on the Microchip site you will find all the app notes you will
    need. Look at PIC Microcontrollers. http://www.microchip.com/

    N
     
  20. hamilton

    hamilton Guest

    Darren,

    Your email is bogus.

    If you want this project, you will have to send me an email.

    hamilton AT dimensional DOT com
     
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