16f877a: PCLATH register

[herve]

Could somebody give me a simple example, showing how to use " PCLATH register", in a short program. My objective is to solve the message 306: Crossing page boundary - ensure page bits are set", which appears in my program. My program is done with MPLAB IDE V6.60.

Thank you in advance,

Best regards,

Hervé.

[Acetronics2]

Hi,Herve

You can forget about Message 306 ... PBasic cares for you !!!

It can be cancelled using :

@ Errorlevel -306

at the top of your program ...

OR using PM Compiler ... !!!

Now PCLATH permits to use a larger adressing range than an asm CALL allows, Look at fig 2.3 p 19 of the Datasheet : it explains the different BANKS of memory. PCLATH permits to choose one of these Banks.

a look at page 32 will show you how addressing is done ...

Good readings
Alain

[herve]

Hello Acetronics,
I have already used "ERRORLEVEL - 306". It was OK to suppress the message, but when I launched the program, I faced with problems at the level where the message 306 was indicated (before the addition of "ERRORLEVEL-306"). So, I concluded that I could not ignore this message.

I am going to analyse the datasheet, in accordance with your proposal, but could you give me a short example of program using PCLATH register, in order that it completes my analysis efficiency ?

Thank you in advance,

Best regards,

Hervé.

[paul borgmeier]

also look here
http://www.picbasic.co.uk/forum/showthread.php?t=555

[Acetronics2]

Hello Acetronics,
I faced with problems at the level where the message 306 was indicated , ... but could you give me a short example of program using PCLATH register, in order that it completes my analysis efficiency ?

Hervé.

Hi, Hervé

Using pure PbP would never involve such problems ... sooooooo, WHAT do you do and want to do here ????????????????????

My crystal ball is gone for holidays ...

Alain

[Dave]

herve, The message is just a warning. As long as you are not using the BRANCH statement you should be OK. If you are using the BRANCH statement in your program then change it to BRANCHL. This is the BranchLong statement and is used when branching to other parts of your program that are not in the same page (crossing page boundries).

Dave Purola,
N8NTA

[herve]

Hello Dave and Alain,
I am not using any "BRANCH procedure". My program is only using a lot of "GOTO" and "CALL" instructions. People explained me that this large number of "GOTO" and "CALL" is the reason why there is the message 306 (Crossing page boundary -- ensure page bits are set): the pic program memory (where my program is saved) is divided into pages due to limitation in the program counter size that can't carry the whole address bits for the whole memory. My program may have exceeded the size of one page so it crossed the page boundries to the next page. So the pc (program counter) overflowed.

The solution would be to adjust PCLATH register.

That is why I would like someone to give me an example of PCLATH use, through a short program, in order that I could know how to do with this PCLATH.

If you could help me, I thank you in advance,

Best regards,

Hervé.