[vdr] Re: Increasing SDRAM on DVB cards

["Martin Kemper" <martin-kemper@web.de>]

Hello again,
vdr@linuxtv.org schrieb am 17.06.03 19:22:55:
> 
> Klaus Schmidinger wrote:
> 
> 
> 
> >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?
> 
> We really need more detailed info on the DSP.
> 
> IF the DSP can adress the entire range between CC000000-CDFFFFFF so not
> mentioned as two
> 2MB blocks and the DSP's adress bus is wide enough to adress the 4MB
> block
> then the available chip select line is enough.
> 

If I understand the datasheet in the right way the DSP make an "Autoconfig" of the SDRAM
at startup(powerup) so as mentioned in the datasheet there is only the way to conect 4 Mbit or 16 Mbit ram´s.

> It's not abnormal that a DSP offers two ways to connect ram onto the
> device.
> Unfortunatly, it might be not so easy to find a suitable 32Mbit chip and
> if a 16Mbit is used,
> then you need chip select line 2 to use it.
> 64mbit chips are easy to find but usual in 54 pin housings so too big.
> 
> So it might be a good idea to focus on the extra adres lines too cause
> that seems
> a more easy way, unless the second chip select is easy to catch for.
> 
> Note at Klaus:
> 
> Let's assume that a card has 4Mbyte , for what whould you use it for?
> 
> 
> 
> 
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> 
by the way at all developer thank´s for this amazing job, i love it.
 
bye 

Martin Kemper

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