piclist 2008\07\23\131058a >
Thread: Sd card interface
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face BY : Herbert Graf email (remove spam text)



On Mon, 2008-07-21 at 21:03 -0300, John Coppens wrote:
> On Mon, 21 Jul 2008 16:35:55 -0700 (PDT)
> threewheeler7 <spamBeGonethreewheeler7RemoveMEspamhotmail.com> wrote:
>
> >
> > i do beleve that the mmc interface is the SPI interface, am i correct?
>
> Yes... And just to point out the largest stumbling block: all of the
> filesystems use 512-byte 'sectors'. So you need a PIC with at least 512
> bytes of memory to store one complete sector (which is why all the
> references point to the larger PICs).
>
> The only exception, is that you could only partially write each sector,
> and then use some program in the PC to put it all together.
>
> As far as I know, that limit is part of the SD norm, and not changeable.

You are correct, however you don't necessarily need a PIC with 512bytes
of RAM to get things going.

For my carmon project http://repatch.dyndns.org:8383/pic_stuff/carmon I
used a 32kB I2C EEPROM for sector storage on a 877. Works to this day
perfectly.

TTYL

<1216833052.9870.11.camel@E2140> 7bit

In reply to: <20080721210335.70dd6af1.john@jcoppens.com>
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