>  I've got my MMC hooked up - the hardware seems OK, but for some reason=

the
> MMC doesn't seem to be responding to an SPI mode entry request. If I se=
nd
the
> card the following packet:
>  0x40 0x00 0x00 0x00 0x00 0x95
> then it should switch to SPI mode and respond with the byte "0x01". My
card
> is responding with a 0x00.

I don't think that command has a useful response.  After you send it, you=

need to send CMD1 (0x41 with arbitrary data and CRC) repeatedly until it
returns 0x00 instead of 0x01.

> What direction is data clocked into an MMC? LSbit to MSbit or MSbit to
LSbit?

MSB first.  The PIC's SPI does the bits in the proper order.

> Do all MMCs support SPI mode? I've got an "Integral" branded MMC here, =
no
> idea who manufactured the IC. The Renesas (Hitachi Semiconductor)
> documentation suggests that SPI mode is listed as "Optional" in the MMC=

> specifications. =


SPI is "optional" in the sense of it being used by the host.  Its
implementation in MMC cards is mandatory, as far as I know.
        Jason Harper

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