Data Transfer Operation

The High Speed MultiMedia Card allows several read/write operations (single block, multiple blocks, stream, etc.). These kinds of transfer can be selected setting the Transfer Type (TRTYP) field in the HSMCI Command Register (HSMCI_CMDR).

In all cases, the block length (BLKLEN field) must be defined either in the HSMCI Mode Register (HSMCI_MR) or in the HSMCI Block Register (HSMCI_BLKR). This field determines the size of the data block.

Consequent to MMC Specification 3.1, two types of multiple block read (or write) transactions are defined (the host can use either one at any time):