Specifications

©Copyright 2001-2013 SD Group (Panasonic, SanDisk, Toshiba) and SD Card Association
Physical Layer Simplified Specification Version 4.10
42
CMD42 Parameter
Current
Card State
PWD_LEN
and PWD
Result of the Function
Card Status
Bit3
Bit2
Bit1
Bit0
Bit25
Bit24
After Power On
Exist
The card is locked
1
0
Cleared
The card is unlocked
0
0
1
0
0
0
Locked
Exist
Force Erase (Refer to Table 4-8)
Table 4-8
1
0
0
0
Unlocked
Exist
Error
0
1
1
0
0
0
Unlocked
Cleared
Error
0
1
0
1
0
0
Locked
Exist
Error
1
1
0
1
0
0
Unlocked
Exist
Lock the card
0 to 1
0
0
1
0
0
Unlocked
Cleared
Error
0
1
0
1
0
1
Locked
Exist
Replace password and the card is still locked
1
0
0
1
0
1
Unlocked
Exist
Replace password and the card is locked
0 to 1
0
0
1
0
1
Unlocked
Cleared
Set Password and lock the card
0 to 1
0
0
0
1
0
Locked
Exist
Clear PWD_LEN and PWD and the card is unlocked
1 to 0
0
0
0
1
0
Unlocked
Exist
Clear PWD_LEN and PWD
0
0
0
0
1
0
Unlocked
Cleared
Error (Note *4 Refer to Table 4-10)
0
1
0
0
0
1
Locked
Exist
Replace password and the card is unlocked
1 to 0
0
0
0
0
1
Unlocked
Exist
Replace password and the card is unlocked
0
0
0
0
0
1
Unlocked
Cleared
Set password and the card is still unlocked
0
0
0
0
0
0
Locked
Exist
Unlock the card
1 to 0
0
0
0
0
0
Unlocked
Exist
Error
0
1
0
0
0
0
Unlocked
Cleared
Error
0
1
Other combinations
Don't care
Don't care
Error (Note *1 Refer to Table 4-10)
0 or 1
1
Table 4-7: Lock Unlock Function (Basic Sequence for CMD42)
Application Note:
To replace password, the host should consider following cases. When PWD_LEN and password
data exist, the card assumes old and new passwords are set in the data structure. When PWD_LEN
and PWD are cleared, the card assumes only new password is set in the data structure. In this case,
the host shall not set old password in the data structure; otherwise, unexpected password is set.
CMD42 Parameter in the data
Bit3: ERASE
Bit2: LOCK_UNLOCK
Bit1: CLR_PWD
Bit0: SET_PWD
Related bits in the Card Status
Bit25: CARD_IS_LOCKED
Bit24: LOCK_UNLOCK_FAILED