Working with an MMC, here's what I do:

Initialize:
CMD0, delay, response 0x01
CMD1, delay---loop until response 0x00, response 0x00

Then, I send the card read command with address 0000 0000, i.e. CMD17. I
should be getting 0x00 after delay and then 0xFE after delay as the start
data token. If there was a failure with the command, I should be getting a
standard R1 error byte. Instead, after sending CMD17, here's what I get in
the next couple response bytes:
0xFF (expected)
0xFE (??!!!; 0x00 skipped)
0x03 (R1 or data error token? If data error token, what would both "Error"
and "CC controller" error mean?)
0xFF
0xFF
0xFF
0xFF
0x0B (R1 or data error?)
0xFF.....continuously

The card works perfectly well in a USB reader for both read/write.

Any clues?

Thanks,
Ishaan

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