MultiMediaCard Protocol - USB Mass Storage: Designing and Programming Devices and Embedded Hosts - page 100

Table 5-3: The MultiMediaCard protocol includes ten classes of comman ds.
Class Number

Class Name SPI Support?

0 basic yes

1 stream read no

2 block read yes

3 stream write no

4 block write yes

5 erase yes

6 write protection yes

7 lock card yes

8 application specific yes

9 I/O mode no

non-storage functions. SPI mode supports everything a mass-storage device
requires, however.
All MultiMediaCards support all of the commands in the basic class. These
commands carry out basic status and control functions. MultiMediaCards
using SPI also support commands in the block-read, block-write, erase,
write-protection, lock-card, and application-specific classes.
A host needs to support only the commands required to carry out its pur-
pose. Some commands are required to initialize the card. USB mass-storage
communications read and write blocks of data, so a MultiMediaCard host in
a USB mass-storage device uses block-read and block-write commands to
access the MultiMediaCard's storage media.
The descriptions that follow apply to a MultiMediaCard host using the SPI
bus. A host using the MultiMediaCard bus can accomplish the same things,
but the command and response formats and protocols vary as described in
the MultiMediaCard specification.

Commands Used by Mass-storage Devices
Table 5-4 shows basic-class commands that flash-memory MultiMediaCard
hosts typically support in USB mass-storage devices.
Table 5-5 shows commands used in reading and writing blocks of data. The
commands that read or write data require a starting address to read or write.