Thank you Don,

but if you want to name a register, which code version would you prefer
and why? Normally one uses the 'equ'-code. But makes this any sense?

Martin


Don Hyde schrieb:

> The code
> counter equ     0x20
>
> sets an "assembler constant" to the hex value 20.  The conversion of the
> symbols "0x20" to a binary value happens when the "equ" line is scanned by
> the assembler, which you can tell because if you make a typo, the error
> message occurs at that point.  Later when you reference "counter", the
> assembler performs a value substitution at that point, inserting the binary
> value just as it would insert the value of a label.
>
> the code
>  #define counter 0x20
>
> tells the assembler to save the text "0x20".  Later when the assembler sees
> "counter", it performs a textual substitution.  If you made a typo in the
> 0x20, the error message would appear at the point where you referred to
> "counter", and not on the line where you made the actual typo.  Since it's
> text, you can put anything into a #define that you want
> (for instance #define Serial_In PORTC,7 ), and it works or doesn't work
> depending on the context where you later use it.  In this case,
>         btfsc   Serial_In
> would work, but
>         goto    Serial_In
> would get an error because a comma is illegal in the target of a goto.
>