at49bv320ct ATMEL Corporation, at49bv320ct Datasheet - Page 6

• Manufacturer Part Number: at49bv320ct
• Description: 32-megabit 2m X 16 3-volt Only Flash Memory
• Manufacturer: ATMEL Corporation

4.7.1
4.8
4.8.1
4.8.2
6
Flexible Sector Protection
AT49BV320C(T)
Clear Status Register
Softlock and Unlock
Hardlock and Write Protect
The WSM can set status register bits 1 through 7 and can clear bits 2, 6 and 7; but, the WSM
cannot clear status register bits 1, 3, 4 or 5. Because bits 1, 3, 4 and 5 indicate various error con-
ditions, these bits can be cleared only through the Clear Status Register command. By allowing
the system software to control the resetting of these bits, several operations may be performed
(such as cumulatively programming several addresses or erasing multiple sectors in sequence)
before reading the status register to determine if an error occurred during those operations. The
status register should be cleared before beginning another operation. The Read command must
be issued before data can be read from the memory array. The status register can also be
cleared by resetting the device.
The AT49BV320C(T) offers two sector protection modes, the Softlock and the Hardlock. The
Softlock mode is optimized as sector protection for sectors whose content changes frequently.
The Hardlock protection mode is recommended for sectors whose content changes infrequently.
Once either of these two modes is enabled, the contents of the selected sector is read-only and
cannot be erased or programmed. Each sector can be independently programmed for either the
Softlock or Hardlock sector protection mode. At power-up and reset, all sectors have their Soft-
lock protection mode enabled.
The Softlock protection mode can be disabled by issuing a two-bus cycle Unlock command to
the selected sector. Once a sector is unlocked, its contents can be erased or programmed. To
enable the Softlock protection mode, a two-bus cycle Softlock command must be issued to the
selected sector.
The Hardlock sector protection mode operates in conjunction with the Write Protect (WP) pin.
The Hardlock sector protection mode can be enabled by issuing a two-bus cycle Hardlock Soft-
ware command to the selected sector. The state of the Write Protect pin affects whether the
Hardlock protection mode can be overridden.
To disable the Hardlock sector protection mode, the chip must be either reset or power cycled.
• When the WP pin is low and the Hardlock protection mode is enabled, the sector cannot be
• When the WP pin is high, the Hardlock protection mode is overridden and the sector can be
unlocked and the contents of the sector is read-only.
unlocked via the Unlock command.
3372F–FLASH–4/05