Thanks again David

Forgot to mention that I want to be able to store the table in EEPROM as it
will be part of a LCD menu that can be altered by the user.

How do I set the table up to work in EEPROM?

PS as u can tell I am a new to the AVR but have managed to make a couple of
programs work including one that have entered into the circuit cellar
competition. :-)
*************************************************
Roy Hopkins   :-)

Tauranga
New Zealand
*************************************************
> Thanks for the fast response - will test it out.
>
> ----- Original Message -----
> From: "David VanHorn" <dvanhorn@CEDAR.NET>
> To: <PICLIST@MITVMA.MIT.EDU>
> Sent: Friday, June 11, 2004 7:58 PM
> Subject: Re: [AVR:]Look up Table
>
>
> > At 07:32 PM 6/11/2004 +1200, Hopkins wrote:
> >
> > >How do you program a lookup table in an AVR (ATMega 8) using assembler
> code?
> >
> > Assuming two regs named TEMP, TEMP2, and a ram var called Table_Offset
> with the pointer to the position in the table:
> >
> > Get_Table_Byte:
> >         ldi     TEMP,0                  ;For the 16 bit add to follow
> >         lds     TEMP2,Table_Offset      ;Get the offset
> >         ldi     ZL,low(Table*2)         ;Point at the table
> >         ldi     ZH,high(Table*2)        ;
> >         add     ZL,TEMP2                ;Add the offset as a 16 bit op
> >         adc     ZH,TEMP                 ;so the table can be anywhere.
> >         lpm     ;Defaults to R0, some AVRs can put it in other
registers.
> >
> >         ret     ;Byte (Table offset) of TABLE is now in R0
> >
> > For reading multiple bytes, continue with
> >
> > adiw    ZL,1
> > lpm
> >
> > and so on.
> >
> > Data is stored in WORDS in the AVR rom, but recalled in BYTES.
> > Also, the assembler will append an extra null to the end of a .db that
is
> an odd number of bytes long.
> >
> > TABLE: .db 0x45,0x46,0x47
> >
> > Ends up in rom as 45,46,47,00 << Extra null added by assembler.
> >
> > A table that ends in a null, like:
> >
> > TABLE: .db 0x45,0x46,0x43,0x47,0x00
> >
> > ends up looking like this: 45,46,43,47,00,00



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