SPI Protocol Definition
SanDisk Secure Digital (SD) Card Product Manual, Rev. 1.9 © 2003 SANDISK CORPORATION
5-9
Commands and arguments are listed in Table 5-2.
7-bit CRC Calculation: G(x) = x
7 +
x
3 +
1
M(x) = (start bit)
∗
x
39
+ (host bit)
∗
x
38
+...+ (last bit before CRC)
∗
x
0
CRC[6...0] = Remainder[(M(x)
∗
x
7
)/G(x)]
5.2.2. Command Classes
As in SD mode, the SPI commands are divided into several classes (See Table 5-1). Each class supports a set of
card functions. An SD Card will support the same set of optional command classes in both communication modes
(there is only one command class table in the CSD register). The available command classes, and the supported
commands for a specific class, however, are different in the SD Card and the SPI communication mode.
Note that except the classes that are not supported in SPI mode (class 1, 3 and 9), the mandatory required classes for
the SD mode are the same for the SPI mode.
Table 5-1. Command Classes in SPI Mode
Card CMD Class
(CCC)
Class Description
Supported Commands
0 1 9 10 12 13 16 17 18 24 25 27 28 29 30 32 33 38 42 55 56 58 59
class 0
Basic
+ + + + + +
+ +
class
1
Not
supported
in
SPI
class
2
Block
read
+ + +
class
3
Not
supported
in
SPI
class
4
Block
write
+ + +
class 5
Erase
+
+
+
class
6
Write-protection
(Optional)
+ + +
class
7
Lock
Card
(Optional)*
+
class 8
Application specific
+ +
class
9
Not
supported
in
SPI
class 10-11
Reserved
* The Lock Card command is supported in the SD Card.
5.2.2.1. Detailed Command Description
The following table provides a detailed description of the SPI bus commands. The responses are defined in Section
5.2.3. Table 5-2 lists all SD Card commands. A “yes” in the SPI mode column indicates that the command is
supported in SPI mode. With these restrictions, the command class description in the CSD is still valid. If a
command does not require an argument, the value of this field should be set to zero. The reserved commands are
reserved in SD Card mode as well.
The binary code of a command is defined by the mnemonic symbol. As an example, the content of the
Command
field for CMD0 is (binary) ‘000000’ and for CMD39 is (binary) ‘100111.’
