problem in reset pic 16f877a

Discussion in 'Programmer's Corner' started by mostaghfir, Jun 26, 2012.

  1. mostaghfir

    Thread Starter Member

    Dec 29, 2010
    10
    0
    goodmorning anyone
    - sorry for the language
    - i have a problem in reset of pic 16f877a
    - my crcuit composed from a pic 16f877a to drive 24 ultrabrighte led ; tow press bottom one for automatic drivin and other for hendly driving /
    in the first time the circuit fontionne well ? but if i press bottom to reset the operation . some leds ( 8 last or first leds ) not exteing . pleas where is the problem
    information : - programme doing in c++
    - simple progrmmer driving by 18f2550
    - the pic is made in thailand
    - ther is not the same problem for other pics
    other explication in the attached images :
    Untitled - 1.jpg
    DSC00189.jpg
     
  2. t06afre

    AAC Fanatic!

    May 11, 2009
    5,939
    1,222
    We can not give you any help. With just pictures. Please post your code and schematics:)
     
  3. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,386
    1,605
    We can get around any language problems. I understand it may be difficult if you are not an English speaker but if we all try we can figure it out.

    When you post your schematic please give us a better description of your problem. I am not sure what "exteing" means. Do you mean some LEDs stay on when you press the reset? Do they go off when you release reset or do they still stay on?

    When you say "ther is not the same problem for other pics" do you mean if you change the PIC on this board it runs fine, or do you mean other boards of this design work OK just not this board?

    By the way, your board looks like some good work.
     
  4. mostaghfir

    Thread Starter Member

    Dec 29, 2010
    10
    0
    thank you very much mr t0afre and mr erniem for your quiqly help
    mr erniem :
    - i will try to learn more english
    - "exteing" means as you say some LEDs stay on when i press the reset
    - all boards in this design work fine ? but some pics (remmeber are made inthailand) present the precedent problem
    , i will post the complet shematic in the next time

    my respectable greetings
     
  5. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,386
    1,605
    I think I get your problem now: As you press the reset button going to MCLR some of your LEDs stay on. The problem seems to be limited to PIC chips made in Thailand.

    The PIC internal reset signal should happen when MCLR goes low. If you have some chips that do not do this you may have a problem inside the PIC. I wold first make sure the MCLR signal is clean (really goes to zero) and the LEDs really connect to the outputs.

    If all that is true then you should contact Microchip directly and open a support ticket. They will assist you, though it will take some time for them to work this problem.
     
    mostaghfir likes this.
  6. Markd77

    Senior Member

    Sep 7, 2009
    2,803
    594
    mostaghfir likes this.
  7. mostaghfir

    Thread Starter Member

    Dec 29, 2010
    10
    0
    hello friends :
    here is the schematics diagram (one is of the simulation realised in proteus)
    is there a mistakes in the eletrical schematics ?
    LED flasher20ULN2803A.jpg

    LED flasher16F.jpg
     
  8. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,386
    1,605
    According to both your schematics there is no "reset" button driving the MCLR pin, instead there are two general input switches that your code monitors. This means "reset" is a program controlled event.

    While it is curious that PICs from different countries work differently I would expect that is more of a "clue" to an underlying software issue rather then the direct cause.

    Since you do not use a hardware reset I would expect the problem to have be in the code.

    Maybe post some, either zip or in code tags.
     
    Last edited: Jul 2, 2012
  9. mostaghfir

    Thread Starter Member

    Dec 29, 2010
    10
    0
  10. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,386
    1,605
    No one will ever read a hex file.

    Post the source code of what may be causing the problem.
     
Loading...