AT49SV322D Datasheet, PDF (6/32 Pages) ATMEL Corporation – 32-megabit (2M x 16) 1.8-volt Only Flash Memory

4.7.3
4.7.4
Erase/Program Status Bit
The device offers a status bit on I/O5, which indicates whether the program or erase operation
has exceeded a specified internal pulse count limit. If the status bit is a “1”, the device is
unable to verify that an erase or a word program operation has been successfully performed. If
a program (Sector Erase) command is issued to a protected sector, the protected sector will
not be programmed (erased). The device will go to a status read mode and the I/O5 status bit
will be set high, indicating the program (erase) operation did not complete as requested. Once
the erase/program status bit has been set to a “1”, the system must write the Product ID Exit
command to return to the read mode. The erase/program status bit is a “0” while the erase or
program operation is still in progress. Please see “Status Bit Table” on page 11 for more
details.
VPP Status Bit
The AT49SV322D(T) provides a status bit on I/O3, which provides information regarding the
voltage level of the VPP pin. During a program or erase operation, if the voltage on the VPP
pin is not high enough to perform the desired operation successfully, the I/O3 status bit will be
a “1”. Once the V_PP status bit has been set to a “1”, the system must write the Product ID Exit
command to return to the read mode. On the other hand, if the voltage level is high enough to
perform a program or erase operation successfully, the V_PP status bit will output a “0”. Please
see “Status Bit Table” on page 11 for more details.
4.8 Sector Lockdown
Each sector has a programming lockdown feature. This feature prevents 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 lockdown 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.
4.8.1
Sector Lockdown Detection
A software method is available to determine if programming of a sector is locked down. When
the device is in the software product identification mode (see “Software Product Identification
Entry/Exit” sections on page 25), a read from address location 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 identification exit code should be
used to return to standard operation.
6 AT49SV322D(T)
3623A–FLASH–7/06