AT91FR40162SBPRE Datasheet, PDF (55/214 Pages) ATMEL Corporation – Flash memory in a single compact 121-ball BGA package

AT91FR40162SB
12.3
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.
12.3.1
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 Section 12.8 ”Software Product
Identification Entry” and Section 12.9 “Software Product Identification Exit” on page 66), 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 soft-
ware product identification exit code should be used to return to standard operation.
12.3.2
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.
12.3.3
Erase Suspend/Erase Resume
The Erase Suspend command allows the system to interrupt a sector or chip erase operation
and then program or read data from a different sector within the memory. After the Erase Sus-
pend 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 system can then read data or pro-
gram 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. 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.
12.3.4
Program Suspend/Program Resume
The Program Suspend command allows the system to interrupt a programming operation and
then read data from a different byte/word within the memory. After the Program Suspend com-
mand is given, the device requires a maximum of 10 µs to suspend the programming operation.
After the programming operation has been suspended, the system can then read data from any
other byte/word that is not contained in the sector in which the programming operation was sus-
pended. An address is not required during the program suspend operation. To resume the
programming operation, the system must write the Program Resume command. The program
suspend and resume are one-bus cycle commands. The command sequence for the erase sus-
pend and program suspend are the same, and the command sequence for the erase resume
and program resume are the same.
55
6410B–ATARM–12-Jan-10