| Posted: 11:21am 16 Aug 2020 |
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Hi all. I've been porting a PIC assembly program from MPASM to the newer XC8 assembler and I am struggling with the whole psect thing - I've never used them and the microchip documentation is spinning my head in circles.
Here's a summary of the program:
PIC16F648A processor
4 separate files of code
In file 1 :
A jump at address 0 to Initialisation code (File 2) to be located past the end of the interrupt code (File 3)
More code to end of file - located after the initialisation code (File 2)
In File 2:
Initialisation code
In File 3:
Interrupt code at address 0x04
In File 4:
Code and lookup table in Page 1 memory space.
Previously I had used ORG statements to define where i wanted each piece of code to be located and then included the next file in-line as needed, but according to the XC8 documentation that's not the way to do it. From the MPLABŪ XC8 PICŪ Assembler User's Guide "Note: The much-abused ORG directive does not move the location counter to the absolute address you specify." I guess I was abusing it.....
So, I have this prior to the initial jump in File 1
psect resetVec,class=CODE,delta=2
resetVec:
And this before the interrupt code in file 3
psect code
org 0x004
And this before the other sections of code In file 1 and 2
psect code
And this before the page 1 code in file 4
psect code
org 0x800 ;page 1 program memory space
I know I need to define some sort of reference for the end of each psect that the next one can link from, but I have no idea how to do that as I either can't understand the microchip documentation, or it assumes everyone is a seasoned programmer who has been taught psects somewhere else.
Question is, how do I define the sequence of the psects of code, without actually structuring the code in one file in the order I want. As it stands, the linker chucks errors because it tries to put the code somewhere that only has 0x30 words (no idea where that might be in a '648) - as this error appears for each psect in the source code.
:0:: error: (1347) can't find 0x425 words (0x425 withtotal) for psect "code" in class "CODE" (largest unused contiguous range 0x30)
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