Chapter 4 – SD Card Protocol Description
Revision 2.2
SanDisk SD Card Product Manual
© 2004 SanDisk Corporation
4-18
12/08/04
Table 4-7
Force Erase Function to Locked Card
CMD42 Parameter
TWP
15
Card
Status
Bit3 Bit2 Bit1 Bit0
PWP
14
GWP
16
Result of the Function
Bit25 Bit24
1 0 0 0 Yes Don’t
care
Error
17
1
1
1
0
0
0
No
Yes
Execute force erase & clear
Temporary Write Protect and
Group Write Protect
18
1 to 0
0
1
0
0
0
No
No
Execute force erase
1 to 0
0
•
Relation between ACMD6 and Lock/Unlock State
ACMD6 is rejected when the card is locked and bus width can be changed only when the
card is unlocked. Figure 4-11 shows the relation between ACMD6 and Lock / Unlock state.
Table 4-8
Relationship between ACMD6 and Lock/Unlock State
Card State
Bus Mode
Result of the Function
Unlocked
1-bit
ACMD6 is accepted
Locked
1-bit
ACMD6 is rejected and remains in 1-bit mode
Unlocked
4-bit
ACMD6 is accepted
Locked
4-bit
ACMD6 is rejected and remains in 4-bit mode; CMD0 changes to 1-bit
mode
Note:
After power on (in 1-bit mode), if the card is locked, the SD mode host shall issue
CMD42 in 1-bit mode. If the card is locked in 4-bit mode, the SD mode host shall issue
CMD42 in 4-bit mode.
•
Commands Accepted for Locked Card
The locked card will accept commands listed below and return a response with setting
CARD_IS_LOCKED.
−
Basic class (0)
−
Lock card class (7)
−
CMD16
−
ACMD41
All other commands (including security commands) are treated as illegal commands.
Note:
After power on, the host can recognize the card lock/unlock state by the
CARD_IS_LOCKED in the response of CMD7 or CMD13.
4.4.8
Application-specific
Commands
The SanDisk SD Card is defined to be protocol-forward-compatible to the MultiMediaCard
Standard.
The SD Card system is designed to provide a standard interface for a variety application
types. In order to keep future compatibility to the MultiMediaCard standard together with
14
Write Protection
PWP
: Permanent Write Protect (CSD bit13).
15
Write Protection
TWP
: Temporary Write Protect (CSD bit12).
16
Write Protection
GWP
: Group Write Protect (CMD28, CMD29, CMD30).
17
Refer to Note 2 in Table 4-6.
18
Refer to Note 3 in Table 4-6.