Chapter 3 – SD Card Interface Description
Revision 2.2
SD Card Product Manual
© 2004 SanDisk Corporation
3-23
12/08/04
3.5.7
SD Card Registers in SPI Mode
In SPI mode, all the card’s registers are accessible. Their format is identical to the format in
the SD Card mode. However, a few fields are irrelevant in SPI mode. In SPI mode, the card
status register has a different, shorter, format as well. Refer to the SPI Protocol section for
more details.
3.6
Data Interchange Format and Card Sizes
In general, SD Card data is structured by means of a file system. The SD Card File System
Specification, published by the SD Association, describes the file format system that is
implemented in the SanDisk SD Card. In general, each SD Card is divided into two
separate DOS-formatted partitions as follows:
•
User Area
—used for secured and non-secured data storage and can be accessed by the
user with regular read/write commands.
•
Security Protected Area
—used by copyright protection applications to save security
related data and can be accessed by the host using the secured read/write command
after doing authentication as defined in the SD Security Specification. The security
protected area size is defined by SanDisk as approximately one percent of the total size
of the card. Tables 3-31 and 3-32 describe the user and protected areas for all SanDisk
SD Cards.
Table 3-31
User Area DOS Image Parameters
Capacity Total
LBAs
Number of
Partition
System Area
Sectors
Total Partition
Sectors
User Data
Sectors
User Data
Bytes
16 MB
28,800
39
28,743
28,704
14,696,448
32 MB
59,776
45
59,725
59,680
30,556,160
64 MB
121,856
57
121,817
121,760
62,341,120
128 MB
246,016
95
245,919
245,824
125,861,888
256 MB
494,080
155
493,979
493,824
252,837,888
512 MB
990,976
275
990,627
990,352
507,060,224
1 GB
1,984,000
519
1,983,495
1,982,976
1,015,283,712
2 GB
3,917,072
519
3,967,239
3,966,720
2,030,960,640
Table 3-32
Protected Area DOS Image Parameters
Capacity Total
LBAs
Number of
Partition
System Area
Sectors
Total Partition
Sectors
User Data
Sectors
User Data
Bytes
16 MB
352
35
351
316
161,792
32 MB
736
37
733
696
356,352
64 MB
1,376
37
1,373
1,336
684,032
128 MB
2,624
35
2,611
2,576
1,318,912
256 MB
5,376
37
5,365
5,328
2,727,936