Program Code and Program Memory


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  1. #1
    Join Date
    Feb 2007
    Posts
    4

    Default Program Code and Program Memory

    I am using MicroCode Studio Plus (V2.3.0.0), PBP 2.47, and MPASM.
    I thought that the porgrams were stored from high memory down (as in the MSLoader hex file).
    I just noticed that the code I am loading is going in at the the begining of program memory. It doesn't even skip the Interup Vector locations.

    ????????????

  2. #2
    Join Date
    Jul 2003
    Posts
    2,405

    Default

    Program code for 12-bit & 14-bit core parts always starts at 0. For 18F
    parts, you have the option of using DEFINE RESET_ORG to force the
    reset vector to another location.

    If you're using the MCS loader, just use DEFINE LOADER_USED 1 to leave
    space from 0-4 for the loader jump.

    The MCS loader occupies high memory - so it's out of the way of normal
    program code space.
    Regards,

    -Bruce
    tech at rentron.com
    http://www.rentron.com

  3. #3
    Join Date
    Feb 2007
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    Default

    Interesting, but the code is being written into locations 0008h thru 0018h which the data sheet indicates is for interrupt vectors.

    ??

  4. #4
    Join Date
    Jul 2003
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    Unless you tell PBP to do otherwise, it's always going to drop code in the
    hardware interrupt vector locations.

    Try something like this;
    Code:
    DEFINE  INTHAND HIGH_INT  ' High Priority Ints
    DEFINE  INTLHAND LOW_INT ' Low Priority Ints
    
    ASM
    HIGH_INT
       blah
       blah
    ENDASM
    
    ASM
    LOW_INT
       blah
       blah
    ENDASM
    Now PBP will insert jumps to both of your .asm interrupt handlers at both high
    and low hardware interrupt vectors.

    If you use the BASIC ON INTERRUPT option, PBP will just drop a RETURN at
    location 4.
    Regards,

    -Bruce
    tech at rentron.com
    http://www.rentron.com

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