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How to define a lit23 GOTO in PCD?

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FvM

Joined: 27 Aug 2008
Posts: 2337
Location: Germany

How to define a lit23 GOTO in PCD?

Posted: Thu Sep 25, 2008 8:03 am

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Hello,

in EX_PCD_Bootloader.c, a jump to the real bootloader is performed by

Code:

#asm
goto LOADER_ADDR
#endasm

For most PIC24 chips, LOADER_ADDR is a 23-Bit literal, e. g. 0x207FA.
PCD inserts a far GOTO instruction, but strips of the upper bits. Even inserting 23 Bit constant instead of a symbol doesn't generate the correct address.

There is also a built-in function goto_address(), but it seems to generate a near branch instruction unconditionally.

How to perform the necessary far GOTO?

Regards,
Frank

FvM

Joined: 27 Aug 2008
Posts: 2337
Location: Germany

Posted: Thu Sep 25, 2008 8:30 am

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As an additional question, how to use symbols in literal MOV instructions, e. g.:

Code:

#asm
MOV #LOADER_ADDR, W0

It gives an error Invalid Pre-Processor directive. I don't see that PCD provides an option.

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