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SD Card Interface Description
3-24
SanDisk Secure Digital (SD) Card Product Manual, Rev. 1.9 © 2003 SANDISK CORPORATION
3.5.8. 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:
•
The 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 3-30 and 3-31 describe the user and
protected areas for all SanDisk SD Cards.
Table 3-30. Parameters for User Area DOS Image
Capacity Total
LBAs
No. of Partition
Sys. 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
990,864
275
990,627
990,352
507,060,224
1024 MB
1,983,744
519
1,983,495
1,982,976
1,015,283,712
Table 3-31. Parameters for Protected Area DOS Image
Capacity Total
LBAs
No. of Partition
Sys. 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
5376
37
5365
5328
2,727,936
512 MB
10,240
37
10,213
10,176
5,210,112
1024 MB
20,480
37
20,421
20,384
10,436,608