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Re: Enhanced instruction set

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  • Re: Enhanced instruction set

    I'm curious about the option to enable/disable the enhanced program set during fuse programming. I have a simple program that works fine (18F2423) when I disable the "EIS", but doesn't when I do. I've searched the forums, web etc.

    I'm running current copies of PBP3, U2 Programmer, Microcode Studio plus with the UMC boot loader.

    Thanks for any clarification.

  • #2
    The extended instruction set changes the way the FSR's work, and PBP uses the FSR's quite a bit.

    But PBP cannot use the FSR's the way they get changed by XINST.
    So ALWAYS disable XINST in the configs if that chip has the XINST option.

    And remember that the #CONFIG/#ENDCONFIG block removes all default configurations.
    So you need to explicitly disable XINST in each program.
    PBP3 Manual : Microchip Datasheets - 10F, 12F, 16F, 18F
    Never download a PIC datasheet from anywhere but microchip.com

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    • #3
      Thank you for the explanation Darrel, and the warning about the configs. I'm using the UMC program and setting my defines in the builder application.

      Is there a preference on the "stack over flow/reset" config? Sorry if the terminology isn't correct, don't have a programmer in front of me. If I remember correctly this config instructs the micro on what to do in the event of a stack overflow?
      Thanks

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      • #4
        Since a well written program would never over/underflow the stack... it should not matter which way you set it.

        But if you are unsure of whether the program is "Well Written", you can enable STVREN and the PIC will reset if an over/underflow condition occurs.

        You can then check the STKFUL/STKUNF bits in the STKPTR register at the beginning of your program to determine if the reset was normal or from a stack problem.
        PBP3 Manual : Microchip Datasheets - 10F, 12F, 16F, 18F
        Never download a PIC datasheet from anywhere but microchip.com

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