at49bv3218 ATMEL Corporation, at49bv3218 Datasheet - Page 5

• Manufacturer Part Number: at49bv3218
• Description: 32-megabit 2mx16/4mx8 3-volt Only Flash Memory
• Manufacturer: ATMEL Corporation

AT49BV/LV3218(T)
SECTOR LOCKDOWN: Each sector has a programming lockdown feature. This feature pre-
vents programming of data in the designated sectors once the feature has been enabled.
These sectors can contain secure code that is used to bring up the system. Enabling the lock-
down feature will allow the boot code to stay in the device while data in the rest of the device is
updated. This feature does not have to be activated; any sector’s usage as a write protected
region is optional to the user.
At power-up or reset all sectors are unlocked. To activate the lockdown for a specific sector,
the six-bus cycle Sector Lockdown command must be issued. Once a sector has been locked
down, the contents of the sector is read-only and cannot be erased or programmed.
SECTOR LOCKDOWN DETECTION: A software method is available to determine if program-
ming of a sector is locked down. When the device is in the software product identification
mode (see Software Product Identification Entry and Exit sections) a read from address loca-
tion 00002H within a sector will show if programming the sector is locked down. If the data on
I/O0 is low, the sector can be programmed; if the data on I/O0 is high, the program lockdown
feature has been enabled and the sector cannot be programmed. The software product identi-
fication exit code should be used to return to standard operation.
SECTOR LOCKDOWN OVERRIDE: The only way to unlock a sector that is locked down is
through reset or power-up cycles. After power-up or reset, the content of a sector that is
locked down can be erased and reprogrammed.
ERASE SUSPEND/ERASE RESUME: The Erase Suspend command allows the system to
interrupt a sector erase operation and then program or read data from a different sector within
the same plane. Since this device has a dual-plane architecture, there is no need to use the
Erase Suspend feature while erasing a sector when you want to read data from a sector in the
other plane. After the Erase Suspend command is given, the device requires a maximum time
of 15 µs to suspend the erase operation. After the erase operation has been suspended, the
plane that contains the suspended sector enters the erase-suspend-read mode. The system
can then read data or program data to any other sector within the device. An address is not
required during the Erase Suspend command. During a sector erase suspend, another sector
cannot be erased. To resume the sector erase operation, the system must write the Erase
Resume command. The Erase Resume command is a one-bus cycle command, which does
require the plane address (determined by A20 - A19). The device also supports an erase sus-
pend during a complete chip erase. While the chip erase is suspended, the user can read from
any sector within the memory that is protected. The command sequence for a chip erase sus-
pend and a sector erase suspend are the same.
PRODUCT IDENTIFICATION: The product identification mode identifies the device and man-
ufacturer as Atmel. It may be accessed by hardware or software operation. The hardware
operation mode can be used by an external programmer to identify the correct programming
algorithm for the Atmel product.
For details, see “Operating Modes” on page 13 (for hardware operation) or “Software Product
Identification Entry/Exit” on page 20. The manufacturer and device codes are the same for
both modes.
128-BIT PROTECTION REGISTER: The device contains a 128-bit register that can be used
for security purposes in system design. The protection register is divided into two 64-bit
blocks. The two blocks are designated as block A and block B. The data in block A is non-
changeable and is programmed at the factory with a unique number. The data in block B is
programmed by the user and can be locked out such that data in the block cannot be repro-
grammed. To program block B in the protection register, the four-bus cycle Program
Protection Register command must be used as shown in the Command Definition table on
page 7. To lock out block B, the four-bus cycle Lock Protection Register command must be
used as shown in the Command Definition table. Data bit D1 must be zero during the fourth
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