microSDXC Card not responding to SD Interface commands in 3.3V mode
I have recently made a SD/MMC interface (for a FPGA). IMHO, the standard do not make much sense.

Anyway :


My init sequence starts with CMD0 / CMD8 / ACMD41 (repeated) / CMD2 / CMD3...
You may need to send ACMD41 several times.
In normal mode, the card changes outputs on falling edges, in high speed mode (up to 50MHZ), the card changes outputs on rising clock edges.


Hope this helps...

(I have tried SD, SDHC, MicroSDHC and MMCmobile cards, but no MicroSDXC.)