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eSDHC CMD protocol problem on QorIQ

Question asked by rvj on Oct 13, 2012
Latest reply on May 9, 2013 by rvj

Has anyone ever seen 6 bit messages on eSDHC CMD lines?


(FYI, the processor I am using is the P2020, but this seems to be a generic eSDHC problem).


The symptoms are that the processor will not recognise the SDHC card at all - not just a failure to mount, but wont recognise the card at all.


If you look at the command sequence being transmitted on the CMD line from the processor, instead of the usual 48 bit messages, it only transmits 6 bit messages.

The messages start with the correct bits, and end with the required stop bit, but all the other 42 bits are missing.


Something is telling the processor to behave this way - if anyone can help, I'd be very grateful.