
MultiMediaCard
TM
26
Sep.22.2005
Revision 0.3
The following sections describe the CSD fields and the relevant data types. If not explicitly defined otherwise, all bit strings
are interpreted as binary coded numbers starting with the left bit first.
CSD_STRUCTURE
Describes the version of the CSD structure.
SPEC_VERS
Defines the MultiMediaCard System Specification version supported by the card.
TAAC
Defines the asynchronous part of the data access time.
NSAC
Defines the typical case for the clock dependent factor of the data access time. The unit for NSAC is 100 clock cycles.
Therefore, the maximal value for the clock dependent part of the data access time is 25.5k clock cycles.
The total access time N
AC
as expressed in Table 23 is calculated based on TAAC and NSAC. It has to be computed by the
host for the actual clock rate. The read access time should be interpreted as a typical delay for the first data bit of a data
block or stream.
CSD_STRUCTURE
CSD structure version
CSD version No. 1.0
CSD version No. 1.1
CSD version No. 1.2
Version is coded in the CSD_STRUCTURE byte in the EXT_CSD register
Valid for System Specification Version
Version 1.0 - 1.2
Version 1.4 - 2.2
Version 3.1 - 3.2 - 3.31 - 4.0 - 4.1
0
1
2
3
SPEC_VERS
System Specification Version Number
0
1
2
3
4
5 - 15
Version 1.0-1.2
Version 1.4
Version 2.0 - 2.2
Version 3.1 - 3.2 -3.31
Version 4.0 - 4.1
Reserved
TAAC bit position
code
2:0
Time unit
0=1ns, 1=10ns, 2=100ns, 3=1μs, 4=10μs, 5=100μs, 6=1ms, 7=10ms
Multiplier factor
0=reserved, 1=1.0, 2=1.2, 3=1.3, 4=1.5, 5=2.0, 6=2.5, 7=3.0, 8=3.5, 9=4.0, A=4.5,
B=5.0, C=5.5, D=6.0, E=7.0, F=8.0
Reserved
6:3
7