Product manual

Industrial Grade SD Card Interface Description

NOTE: The device size indicates the user area size. It does not include the protected area that is used for security applications

and is about 1 percent of the total card size.

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.

Table 3-11. CSD Register Structure

CSD_STRUCTURE CSD Structure Version Valid for SD Card Physical

Specification Version

0 CSD version No. 1.0 Version 1.0-1.01

1-3 Reserved

TAAC—Defines the asynchronous part (relative to the SD Card clock (CLK)) of the read access time.

Table 3-12. TAAC Access Time Definition

TAAC Bit

Position

Code

2:0 time unit

0=1ns, 1=10ns, 2=100ns, 3=1µms, 4=10µms, 5=100µms, 6=1ms, 7=10ms

6:3 time value

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

7 Reserved

NSAC—Defines the worst 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 read access time is 25.5k clock

cycles.

The total read access time N

as expressed in the Table 5-17 is the sum of 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 from the end bit on the read commands.

TRAN_SPEED—Table 3-13 defines the maximum data transfer rate TRAN_SPEED.

Table 3-13. Maximum Data Transfer Rate Definition

TRAN_SPEED Bit Code

2:0 transfer rate unit

0=100kbit/s, 1=1Mbit/s, 2=10Mbit/s, 3=100Mbit/s, 4... 7=reserved

6:3 time value

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

7 Reserved

CCC—The Industrial Grade SD 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. Table 3-14 lists the supported card command classes; refer to

Table 4-2 for command class definitions.