Chapter 4 – SD Card Protocol Description
Revision 2.2
SanDisk SD Card Product Manual
© 2004 SanDisk Corporation
4-17
12/08/04
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Two types of Lock/Unlock Card
There will be two types of lock / unlock function-supported cards. Type 1 is an older
version of the SD Card, and Type 2 is the new version defined in this specification (v1.10).
Table 4-6 shows the difference between these types of cards. The SD cards that support
Lock /Unlock and comply with Version 1.01, can take either Type 1 or Type 2. SD cards
that support Lock / Unlock and comply with Version 1.10, take Type 2.
Table 4-6
Type 1 vs. Type 2 Card of Lock/Unlock Function
Note
Type 1 Card (older version)
Type 2 Card (new version)
1
Treat CMD42 Parameter=0011b as 0001b.
Treat CMD42 Parameter=0111b as 0101b.
Treat CMD42 Parameter=0110b as 0010b.
Results of other combinations are Error.
All results are each an “error.”
2
Execute force erase and set Permanent Write Protect. If
force erase is completed, the CARD_IS_LOCKED is
changed from 1 to 0. A priority is given to force erase
from Permanent Write Protect.
Results in an “error”
A priority is given to Permanent
Write Protect from force erase.
3
Execute force erase but Temporary Write Protect and
Group Write Protect are not cleared. It is in need of the
host clear.
Execute force erase and clear
Temporary Write Protect and
Group Write Protect.
4
CMD42 Parameter=0010 and CMD42 Parameter=0110
The result is no error.
Card status Bit24 will be 0.
Results in an “error”. Card
status Bit24 will be 1.
Note:
The host can use both types of card without checking difference by taking account
of following points.
(1) The host should not set the parameters of CMD42 that return error in Table 4-5. (For
*1)
(2) The host should not issue force erase command if the Permanent Write Protect is set to
1, otherwise the Type 1 card cannot be used any more even if the user remembers the pass
word. (For *2)
(3) After the force erase, if the Temporary Write Protect is not cleared, the host should clear
it. (For *3)
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Force Erase Function to the Locked Card
Figure 4-5 clarifies the relation between Force Erase and Write Protection. The Force Erase
does not erase the secure area. The card shall keep locked state during the erase execution
and change to unlocked state after the erase of all user area is completed. Similarly, The
card shall keep Temporary and Group Write Protection during the erase execution and clear
Write Protection after the erase of all user area is completed. In the case of erase error
occur, the card can continue force erase if the data of error sectors are destroyed.