Forums

128k of external Data RAM

Started by atid2 August 10, 2003
Hi all,

I would like to use 128k of external Data RAM with the DSP56F827.
I'm currently using 64K of XRAM.
What is the procedure I have to take in order to achive it?

Thank you in advance,
Ari.



Hello Ari,
You can use 64K external data memory and 64k external program
memory, but no way to use 128k data memory in DSP56F827.

Regards
Hong

--- In , "atid2" <arit@j...> wrote:
> Hi all,
>
> I would like to use 128k of external Data RAM with the DSP56F827.
> I'm currently using 64K of XRAM.
> What is the procedure I have to take in order to achive it?
>
> Thank you in advance,
> Ari.





There is always a way...

I imagine the best way to do this is to dedicate about 32K (or what
ever number) to stack and global data. Then the remaining 96K should
be divided into three banks that can be selected with port outputs.
Then just make a 32K array that points to the non-stack area. The
downside is prior to accessing this non-stack area you have to select
witch of the three banks you wish to access. The Archimedes linker I
used to us for the HC11 even had a feature built in where you could
specify your bank switching routine and then memory access was
transparent to the programmer (hint hint Metrowerks)

Jacob

--- In , "hong_dspnews"
<hong_dspnews@y...> wrote:
> Hello Ari,
> You can use 64K external data memory and 64k external program
> memory, but no way to use 128k data memory in DSP56F827.
>
> Regards
> Hong
>
> --- In , "atid2" <arit@j...> wrote:
> > Hi all,
> >
> > I would like to use 128k of external Data RAM with the DSP56F827.
> > I'm currently using 64K of XRAM.
> > What is the procedure I have to take in order to achive it?
> >
> > Thank you in advance,
> > Ari.





It may possible to do what Jscob proposes. But the debugger will not be able to recognize the upper pages in memory (the 96K)

It would probably also take some tricks in the LCF to get it all to link properly.

You might ought to consider upgrading to a 56858, which supports large memory model already.

Regards

Hong



Jacob Christ <j...@pontech.com> wrote:
There is always a way... 

I imagine the best way to do this is to dedicate about 32K (or what
ever number) to stack and global data.  Then the remaining 96K should
be divided into three banks that can be selected with port outputs. 
Then just make a 32K array that points to the non-stack area.  The
downside is prior to accessing this non-stack area you have to select
witch of the three banks you wish to access.  The Archimedes linker I
used to us for the HC11 even had a feature built in where you could
specify your bank switching routine and then memory access was
transparent to the programmer (hint hint Metrowerks)

Jacob

--- In m...@yahoogroups.com, "hong_dspnews"
<hong_dspnews@y...> wrote:
> Hello Ari,
> You can use 64K external data memory and 64k external program
> memory, but no way to use 128k data memory in DSP56F827.
>
> Regards
> Hong

> --- In m...@yahoogroups.com, "atid2" <arit@j...> wrote:
> > Hi all,
> >
> > I would like to use 128k of external Data RAM with the DSP56F827.
> > I'm currently using 64K of XRAM.
> > What is the procedure I have to take in order to achive it?
> >
> > Thank you in advance,
> > Ari.



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