gnupic: Re: [gnupic] How do I specify certain addresses to not be banked?
Subject:
Re: [gnupic] How do I specify certain addresses to not be banked?
From:
Jesse Gordon ####@####.####
Date:
13 Sep 2009 17:02:51 -0000
Message-Id: <4AAD2043.3020901@nikola.com>
Hi Raphael,
Thank you very much. You were most helpful!
Actually, I was, for some reason, under the impression that the banked
bit was set by default in the assembler - but I see now that for
addresses 0-7f it is not set - which is exactly and perfectly what I want!
Then for my non-"globals" I can just define them with EQU 0x1xx and they
will all use the current bank select.
Thank you very much!
-Jesse
Raphael Neider wrote:
> Hi Jesse,
>
>> And I wish to use the first half of bank 0 as "global" vars in the
>> same way that the second half (the SFRs) are "global."
>>
> [>>snip<<]
>> So, here is the question: How can I make some of my own ram locations
>> also always be accessed in bank 0 without me having to specify the
>> ",0" on every file instruction?
>>
>> For example, if I do:
>>
>> MyGlobalByte EQU 0xF01
>>
>> As it is, the assembler just drops the F00 part and a CLRF on
>> MyGlobalByte will clear byte 1 in the currently selected bank. Why
>> can't the assembler see that I've specified 0xF01 and automatically
>> clear the use-bank-selected bit - Just like it does for addresses
>> above 0xF80?
>
> The PICs have an access bank, which is split into general purpose
> registers (often 0x00 - 0x7F, sometimes 0x00 - 0x5F) and special
> function registers (0x80 - 0xFF, which are mapped to 0xF80 - 0xFFF,
> sometimes 0x60 - 0xFF, remapped to 0xF60 - 0xFFF). The split point
> is defined by Microchip and cannot be changed.
> You can use
>
> MyGlobalByte EQU 0x001
> ...
> MyGlobalByte EQU 0x07F
> SFR0xF80 EQU 0xF80
> ...
> SFR0xFFF EQU 0xFFF
>
> and gpasm (knowing the memory layout of the target device) will
> access these via the access bank. All other memory locations
> (0x80 - 0xF7F) will use banked access - so use proper BANKSEL
> directives where needed.
>
> Hope that helps,
> Raphael
>
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