Mass Storage Basics - USB Mass Storage: Designing and Programming Devices and Embedded Hosts - page 22

Table 1-3: Secure Digital (SD) Cards are available in several formats.
Card

SD Card miniSD Card microSD Card

Sponsor

sdcard.org

Physical Size (mm)

32 x 24 x 2.1 20 x 21.5 x 1.4 11 x 15 x 1

Pins

9 11 8

Interface SD Card bus, SPI
Data Bus Width (bits) 1, 4
Maximum Data
Transfer Rate
(Mb/sec.)

100 (SD Card bus); 25 (SPI)

Maximum Clock
Speed (Mbits/sec.)

25

Power Supply (V)

2.7-3.6 or 1.6-3.6(LV)

support for digital rights management

Security

optional no no Write Protect Switch

Membership @$1000/year

Specification Cost

Host/ancillary product license for $1000/year, available to members
only

Licensing Fees and
Royalties

enable reading additional status information and controlling a pull-up on
the Card Detect pin.

Fees
Implementing an SD-Card host isn't practical for developers of inexpensive
products that sell in modest quantities. Every device that contains an
SD-Card host must be licensed. At this writing, it costs $1000/year to join
the SD Card Association and another $1000/year for a member to license a
host. Membership includes access to the SD Card specifications.
If you don't need the additional capabilities of SD Cards, a MultiMediaCard
host is a less expensive option. If you use a connector wide enough to accept
SD Cards, the host can communicate with both MultiMediaCards and SD
Cards operated as MultiMediaCard-compatible devices.

CompactFlash
Another option for flash memory is the CompactFlash card (Figure 1-8).
Like MultiMediaCards and SD Cards, CompactFlash cards contain mem-