[vdr] Re: Increasing SDRAM on DVB cards

[Klaus Schmidinger <Klaus.Schmidinger@cadsoft.de>]

Hermann Gausterer wrote:
> 
> > The card has 2MB of DRAM (which is relatively slow) and 2MB of (fast)
> > SDRAM. The SDRAM is the one used for video decoding (buffer) and OSD.
> 
> what are the adress ranges the two consume in the "virtual" rammap
> of the DSP? are the close to another?
> (i think you have access to the firmware-source, and know this, klaus *sfg*)

Take a look at page 13 of the AV7110 data sheet, which shows its
memory map. The SDRAM is at CC000000-CDFFFFFF, while the DRAM is
at 2E000000-2FFFFFFF.

> the reason for my question:
> i think the easiest way for doing this what you want to do is,
> replace the chip with an pincompable type with more capacity
> 
> accourding to the docs, brought to us by Stefaan Coddé (thank you !!)
> the dram chip has 11 adress lines
> and they are used in the form:
> 
> A 0 - A 10
> R o w   A d d r e s s   :   R A 0   ~   R A 1 0 ,   C o l u m n   A d d r e
> s s   :   C A 0   ~   C A 7
> A u t o - p r e c h a r g e   f l a g   :   A 1 0
> 
> but the CHIP (the DIL housing) has allready forseen an A 11
> 
> for this layout, it is clear that A0 - A10 MUST be allready wired to the DSP
> and if we/you get an replacing part, simple look for an which can do
> on bit more on the COLUMN mode and you have your 4mb
> 
> for this to work, the hardware adressdecoder for the two different
> ram chips have to be a GAP between DRAM and SRAM
> 
> this layout is only guesed, for explanation only !!!!!
> 
> 0FFF:FFFF----------------------(x+2 mb)
> ###########    SRAM   #########
> 0FE0:0000----------------------(x mb)
> 
> 003F:FFFF----------------------(4 mb)
> #######  DRAM FUTURE !!! ######
> 001F:FFFF----------------------(2 mb)
> ###########    DRAM   #########
> 0000:0000----------------------(0 mb)
> 
> with this no change to the hardware decoder would be needed
> but only somebody with knowledge of the firmewareinternals
> can answer and help here !

Well, since SDRAM goes from CC000000-CDFFFFFF and only half of that
address space is currently used, your suggestion might work _if_
there are actually enough address lines connected. However, since the
AV7110 has two explicit SCS lines (SCS1 and SCS2) I would assume that
it can handle either one or two 2MB chips, each connected to its very
own SCSn line.

But I'm just guessing here... Maybe you're actually on the right track.
But then again, what would the SCS2 pin be for?

Klaus
-- 
_______________________________________________________________

Klaus Schmidinger                       Phone: +49-8635-6989-10
CadSoft Computer GmbH                   Fax:   +49-8635-6989-40
Hofmark 2                               Email:   kls@cadsoft.de
D-84568 Pleiskirchen, Germany           URL:     www.cadsoft.de
_______________________________________________________________


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