S
S
S
D
D
D
8
8
8
0
0
0
s
s
s
e
e
e
r
r
r
i
i
i
e
e
e
s
s
s
Rev1.2
SD80 Secure Digital Card
Transcend Information Inc.
14
Note that for current SD Memory Cards that field must be always 0_0110_010b (032h) which is equal to 25MHz - the
mandatory maximum operating frequency of SD Memory Card.
In High-Speed mode, that field must be always 0_1011_010b (05Ah) which is equal to 50MHz. And when the timing
mode returns to the default by CMD6 or CMD0 command, its value will be 032h.
•
CCC
The SD Memory Card command set is divided into subsets (command classes). The card command class register
CCC defines which command classes are supported by this card. A value of ‘1’ in a CCC bit means that the
corresponding command class is supported.
•
READ_BL_LEN
This field is fixed to 9h, which indicates READ_BL_LEN=512 Byte.
•
READ_BL_PARTIAL
This field is fixed to 0, which indicates partial block read is inhibited and only unit of block access is allowed.
•
WRITE_BLK_MISALIGN
This field is fixed to 0, which indicates write access crossing physical block boundaries is always disabled in High
Capacity SD Memory Card.
•
READ_BLK_MISALIGN
