MC56U032NCFA Samsung Semiconductor, Inc., MC56U032NCFA Datasheet - Page 38

• Manufacturer Part Number: MC56U032NCFA
• Description: Flash Card
• Manufacturer: Samsung Semiconductor, Inc.

4.9.4 Write Protect Management
4.9.5 Card Lock/Unlock Operation
Table 4-9 Card Lock Data Structure
MultiMediaCard
ERASE_GROUP_END(CMD36) command and finally it starts the erase process by issuing the
ERASE(CMD38) command. The address field in the erase commands is an Erase Group address in
byte units. The card will all LSB’s below the Erase Group size, effectively rounding the address down to
the Erase Group boundary.
If an erase command is received out of sequence, the card shall set the ERASE_SEQ_ERROR bit in
the status register and reset the whole sequence.
If an out of sequence(neither of the erase commands, except SEND_STATUS) command received, the
card shall set the ERASE_RESET status bit in the status register, reset the erase sequence and
execute the last command.
If the erase range includes write protected blocks, the shall be left intact and only the non-protected
blocks shall be erased. The WP_ERASE_SKIP status bit in the status register shall be set.
As described above for block write, the card will indicate that an erase is in progress by holding DAT
low The actual erase time may be quite long, and the host may issue CMD7 to deselect the card.
Card data may be protected against either erase or write. The entire card may be permanently write
protected by the manufacturer or content provider by setting the permanent or temporary write protect
bits in the CSD. Portions of the data may be protected (in units of WP_GRP_SIZE sectors as specified
in the CSD), and the write protection may be changed by the application. The SET_WRITE_PROT
command sets the write protection of the addressed write-protect group, and the CLR_WRITE_PROT
command clears the write protection of the addressed write-protect group. The SEND_WRITE_PROT
command is similar to a single block read command. The card shall send a data block containing 32
write protection bits (representing 32 write protect groups starting at the specified address) followed by
16 CRC bits. The address field in the write protect commands is a group address in byte units. The
card will ignore all LSB’s below the group size.
The password protection feature enables the host to lock a card while providing a password, which
later will be used for unlocking the card. The password and its size are kept in a 128-bit PWD and 8-bit
PWD_LEN registers, respectively. These registers are non-volatile so that a power cycle will not erase
them. Locked cards respond to (and execute) all commands in the "basic" command class (class 0)
and “lock card” command class. Thus the host is allowed to reset, initialize, select, query for status,
etc., but not to access data on the card. If the password was previously set (the value of PWD_LEN is
not‘0’) will be locked automatically after power on. Similar to the existing CSD and CID register write
commands the lock/unlock command is available in "transfer state" only. This means that it does not
include an address argument and the card has to be selected before using it. The card lock/unlock
command has the structure and bus transaction type of a regular single block write command. The
transferred data block includes all the required information of the command (password setting mode,
PWD itself, card lock/unlock etc.). The following table describes the structure of the command data
block.
Byte#
0
1
2
…
PWD_LEN+1
Bit7
TM
Bit6
Reserved
Bit5
Bit4
Password data
PWD_LEN
Bit3
ERASE
Bit2
LOCK_
UNLOCK
Bit1
CLR_
PWD
SET_
PWD
Bit0
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