SDMJ-32 SanDisk, SDMJ-32 Datasheet - Page 46

• Manufacturer Part Number: SDMJ-32
• Manufacturer: SanDisk
• Type: MultiMedia Cardr

Specifications of SDMJ-32

• Density: 32MByte
• Operating Supply Voltage (typ): 3.3V
• Operating Temperature (min): -25C
• Operating Temperature (max): 85C
• Package Type: MMC
• Mounting: Socket
• Pin Count: 7
• Operating Temperature Classification: Commercial
• Operating Supply Voltage (min): 2.7V
• Operating Supply Voltage (max): 3.6V
• Programmable: Yes
• Lead Free Status / RoHS Status: Compliant

Revision 1.3
© 2005 SanDisk Corporation
4.2.6
4.2.5
Write Protect Management
Card Lock/Unlock Operation
Write protection features may protect MultiMediaCard/RS-MultiMediaCard data 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 also be protected in units of WP_GRP_SIZE sectors
as specified in the CSD. 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
will 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 LSBs
below the group size.
The password protection feature enables the host to lock a card while providing a password
that will be used later for unlocking the card. The password and its size are kept in 128-bit
PWD and 8-bit PWD_LEN registers, respectively. These registers are non-volatile which
protects a power cycle erase.
Locked cards respond to, and execute, all commands in the basic command class (class 0)
and lock card command class. Therefore, the host is allowed to reset, initialize, select,
query for status, etc., but not access data on the MultiMediaCard/RS-MultiMediaCard. If
the password was previously set, it 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; 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 required information
of the command—for example, password setting mode, PWD itself, card lock/unlock, etc.
Table 4-2 describes the structure of the command data block.
Table 4-2
PWD_LEN
ERASE
LOCK/UNLOCK
Byte
+ 1
…
Bit Name
0
1
2
Bit
7
Lock Card Data Structure
1 = Forced Erase Operation (all other bits shall be ‘0’) and only the CMD byte is
sent.
1 = Lock the card.
0 = Unlock the card (it is valid to set this bit together with SET_PWD but it is not
Reserved
Bit
6
Bit
5
Bit
4
4-8
ERASE
Bit 3
MultiMediaCard/RS-MultiMediaCard Product Manual
Password Data
PWD_LEN
Chapter 4 – MultiMediaCard Protocol Description
Description
LOCK_UNLOCK
Bit 2
CLR_PWD
Bit 1
SET_PWD
04/22/05
Bit 0