Mass Storage Basics - USB Mass Storage: Designing and Programming Devices and Embedded Hosts - page 18

Table 1-2: MultiMediaCards are available in several formats.
Card

MultiMediaCard RS-
MultiMediaCard

MMCplus MMCmobile MMCmicro

Sponsor

mmca.org

Physical Size
(mm)

32 x 24 x 1.4 18 x 24 x 1.4 32 x 24 x 1.4 18 x 24x 1.4 14 x 12 x 1.1

Pins

7 13 10

Interface

MultiMediaCard bus (serial),
SPI

MultiMediaCard bus (serial or parallel), SPI

Data Bus
Width (bits)

1 1, 4, 8 1, 4

Maximum
Data Transfer
Rate
(Mbits/sec.)

20 416 208

Maximum
Clock Speed
(Mbits/sec.)

20 52 52

3/3.3/1.8 Power

Supply (V)

SecureMMC interface supports digital rights management Security

Specification
Cost

$500 or MMCA member
@$2500/year

$1000 or MMCA member @$2500/year
(includes all MultiMediaCard variants)

none

Licensing
Fees and
Royalties

4-bit parallel MultiMediaCard bus. The MMCplus and MMCmobile can
use an 8-bit parallel MultiMediaCard bus.
An SPI host must have a clock output (SCLK), a data output (DataIn on the
card), and a data input (DataOut on the card). The host must also control a
unique chip-select output (CS) for each device the host communicates with.
A MultiMediaCard-bus host must have a clock output (CLK), a bidirec-
tional pin for commands (CMD), and a bidirectional pin for data (DAT).
The master uses commands to assign addresses and select cards, so the Mul-
tiMediaCard bus doesn't need a chip-select line for each card.
On power-up, a MultiMediaCard must be clocked at 400 kHz or less.
When the initialization procedure is complete, the host can increase the
clock frequency.