
MultiMediaCard Flash
Preliminary MultiMediaCard Product Manual;
1998 SANDISK CORPORATION
Page 54 of 79
The CRC7 checksum is computed by the following formula:
CRC Calculation: G(x) = x
7
+ x
3
+ 1
M(x) = (MID-MSB)
x
119
(CIN-LSB)
x 0
CRC[6...0] = Remainder[(M(x)
x
7
)/G(x)]
5.8.3 CSD Register
The Card-Specific Data register provides information on how to access the card contents.
The CSD defines the data format, error correction type, maximum data access time, data
transfer speed, whether the DSR register can be used etc. The programmable part of the
register (entries marked by W or E, see below) can be changed by CMD27. The type of
the entries in the table below is coded as follows: R = readable, W = writable once, E =
erasable (multiple writable).
Table 5-13 The CSD Fields
Name
Field
Width
Cell Type
CSD-slice
CSD Structure
CSD_STRUCTURE
2
R
[127:126]
MultiMediaCard Protocol Version
MMC_PROT
4
R
[125:122]
Reserved
-
2
R
[121:120]
Data Read Access-Time-1
TAAC
8
R
[119:112]
Data Read Access-Time-2 In CLK Cycles
(NSAC*100)
NSAC
8
R
[111:104]
Max. Data Transfer Rate
TRAN_SPEED
8
R
[103:96]
Card Command Classes
CCC
12
R
[95:84]
Max. Read Data Block Length
READ_BL_LEN
4
R
[83:80]
Partial Blocks For Read Allowed
READ_BL_PARTIAL
1
R
[79:79]
Write Block Misalignment
WRITE_BLK_MISALIGN
1
R
[78:78)
Read Block Misalignment
READ_BLK_MISALIGN
1
R
[77:77]
DSR Implemented
DSR_IMP
1
R
[76:76]
Reserved
-
2
R
[75:74]
Device Size
C_SIZE
12
R
[73:62]
Max. Read Current @V
DD
Min.
VDD_R_CURR_MIN
3
R
[61:59]
Max. Read Current @V
DD
Max.
VDD_R_CURR_MAX
3
R
[58:56]
Max. Write Current @V
DD
Min.
VDD_W_CURR_MIN
3
R
[55:53]
Max. Write Current @V
DD
Max.
VDD_W_CURR_MAX
3
R
[52:50]
Device Size Multiplier
C_SIZE_MULT
3
R
[49:47]
Erase Sector Size
SECTOR_SIZE
5
R
[46:42]
Erase Group Size
ERASE_GRP_SIZE
5
R
[41:37]
Write Protect Group Size
WP_GRP_SIZE
5
R
[36:32]
Write Protect Group Enable
WP_GRP_ENABLE
1
R
[31:31]
Manufacturer Default
ECC DEFAULT_ECC
2
R
[30:29]
Stream Write Speed Factor
R2W_FACTOR
3
R
[28:26]
Max. Write Data Block Length
WRITE_BL_LEN
4
R
[25:22]