[s1mp3-dev] the new memory chip trick (was: s1mp3 hardware)

[Alistair Buxton]

On 30/06/06, Bluechip <csbluechip at gmail.com> wrote:
>
>  At 20:05 30/06/2006, you wrote:
>
>
> On 30/06/06, *Jules Kerssemakers* <j_kers at yahoo.co.uk> wrote:
>  Hmm, I just thought of something utterly evil :)
> With this new piggy-backing trick, you can add up to 4 chips if your
> board has a second chip slot...
> 4 chips! That would mean you could build anywhere up to a 4GB player!
> (Or even 8GB if you use the new 2GB samsung chips, but how to get some
> of those :-/ )
>
>
> No, this is not possible. The trick relies on the fact that both of the
> ATJ's chip enable lines are brought out on chip slot 1. You can never have
> more than two chips regardless of arrangement.
>
>
> How about:
>
> ce1  ce2  chip
> 0     1     A
> 1     0     B
> 1     1     C
>
>
That would require extra glue logic, as only one chip may be enabled at a
time. It would also require a lot of modification to the firmware, and would
only be possible if the ATJ allows software control of the CE lines (ie they
are not just wired directly to the internal address bus with glue logic.)

If we are only considering custom firmwares, then it's quite possible to use
spare GPIO lines to control the CE of many flash chips. You will still need
to do a little more soldering, but no extra logic chips would be needed.


-- 
Alistair Buxton
a.j.buxton at gmail.com
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