Block device operations
Low Level SPI driver operations
The ECSD_LowLevel_ShiftData function shifts a byte through to and from the card.
This is the data to shift out.
The data shifted in from the card.
The low level driver must activate (lower) CS (Chip-Select) when this function is called if it is not already activated. Note: You should never call this function directly. The API documentation is present to allow you to write your own low level driver optimized for your hardware.