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Too many Hello's

Discussion in 'Electronic Design' started by ozzy, Sep 11, 2006.

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  1. ozzy

    ozzy Guest

    Hi all,

    I've been trying to programme a LCD (HD44780) with a PIC, (16f84A) but
    come across a problem I'd like to share with this forum. I have
    managed to initialise the LCD and got it to write 'HELLO'. But
    unfortunately it continually repeats this, even though my program
    should lock-up. I have checked the reset pin (MCLR) but have that held
    at 5V. I've messed around with the command control codes, but that
    does'nt appear to make a difference either.

    Any input into this problem would be much appreciated.


    Regards,


    Ozzy
     
  2. Andrew Holme

    Andrew Holme Guest

    Is the watchdog restarting it?
     
  3. ozzy

    ozzy Guest


    Andrew,

    Thanks for replying!

    I've actually got this programmed with the Watchdog timer off.
    One thing though - I have the HD44100 driver chips as part of the
    module. Do you think this may have something to do with it?



    Ozzy
     
  4. Jenalee K.

    Jenalee K. Guest

    ozzy a écrit :

    Too many Hello's is better than too many goodbye's ;o)

    Serious though, if it isn't the watchdog then it is probably the power
    supply. Did you put decoupling caps everywhere? It could also be a bug
    in your program... writing an address that you didn't intend to or
    running code that isn't part of your program.

    Thanks,
    Jenalee K.
     
  5. vic

    vic Guest

    Is it a C program ? If so, the C standard startup code will call main()
    if it ever exits, resulting in a loop. You should make sure main() never
    exits or add a while(); at the end.

    vic
     
  6. Genome

    Genome Guest

    There is probably some error in your code.

    Perhaps it's the the way you have initialised the display controller or
    something went wrong when you cut and pasted the example code and modified
    it to do what you want it to do.

    Maybe the code sends the 'Hello' and expects to get some sort of
    acknowledgment from the display and, if it doesn't get it (because the
    display is broken or that part of the code is broken) it sends another
    'Hello' and so things go on.

    DNA
     
  7. Donald

    Donald Guest

    Wouldn't it be easier just to show your code.

    We can not guess at what we can not see.

    A schematic as well.

    donald
     
  8. ozzy

    ozzy Guest


    Thanks for all your replies, but I must say I cocked up big time!!

    The picallw software has a little tick box to the right hand side that
    I did'nt bother with. I had assumed that by clicking the config button
    (at the bottom) and then setting watchdog to off, would do the trick.
    These liitle buttons are only initialised when the ticks on the RHS are
    set.

    I guess I get to face the corner & wear the pointy hat then......
     
  9. ozzy

    ozzy Guest


    Thanks for all your replies, but I must say I cocked up big time!!

    The picallw software has a little tick box to the right hand side that
    I did'nt bother with. I had assumed that by clicking the config button
    (at the bottom) and then setting watchdog to off, would do the trick.
    These liitle buttons are only initialised when the ticks on the RHS are
    set.

    I guess I get to face the corner & wear the pointy hat then......
     
  10. ozzy

    ozzy Guest


    Thanks for all your replies, but I must say I cocked up big time!!

    The picallw software has a little tick box to the right hand side that
    I did'nt bother with. I had assumed that by clicking the config button
    (at the bottom) and then setting watchdog to off, would do the trick.
    These liitle buttons are only initialised when the ticks on the RHS are
    set.

    I guess I get to face the corner & wear the pointy hat then......
     
  11. Joer Breton

    Joer Breton Guest

    You sent the last message three times.
    May be you got stuck in another loop .... :(
    Bad day!

    Joer
     
  12. Guy Fawkes

    Guy Fawkes Guest

    I probably resets when main() terminates. I've seen it many times.
     
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