at49bv320a ATMEL Corporation, at49bv320a Datasheet - Page 7

• Manufacturer Part Number: at49bv320a
• Description: 32-megabit 2m X 16/4m X 8 3-volt Only Flash Memory
• Manufacturer: ATMEL Corporation

3308D–FLASH–5/03
TOGGLE BIT: In addition to Data Polling the AT49BV32XA(T) provides another method for
determining the end of a program or erase cycle. During a program or erase operation, suc-
cessive attempts to read data from the memory will result in I/O6 toggling between one and
zero. Once the program cycle has completed, I/O6 will stop toggling and valid data will be
read. Examining the toggle bit may begin at any time during a program cycle. Please see “Sta-
tus Bit Table” on page 12 for more details.
The toggle bit status bit should be used in conjunction with the erase/program and V
bit as shown in the algorithm in Figures 3 and 4 on page 11.
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 byte/word program oper-
ation 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) opera-
tion 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 12 for more details.
V
tion 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
write the Product ID Exit command to return to the read mode. On the other hand, if the volt-
age level is high enough to perform a program or erase operation successfully, the V
bit will output a “0”. Please see “Status Bit Table” on page 12 for more details.
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/Exit” sections on page 26), 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.
PP
STATUS BIT: The AT49BV32XA(T) provides a status bit on I/O3, which provides informa-
PP
status bit has been set to a “1”, the system must
AT49BV32XA(T)
PP
PP
status
status
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