S25FL128SAGMFI001 Datasheet, PDF (68/153 Pages) SPANSION – CMOS 3.0 Volt Core with Versatile I/O Serial Peripheral Interface with Multi-I/O

Data Sheet
9.4
Advanced Sector Protection
Advanced Sector Protection (ASP) is the name used for a set of independent hardware and software
methods used to disable or enable programming or erase operations, individually, in any or all sectors. An
overview of these methods is shown in Figure 9.1, Advanced Sector Protection Overview on page 68.
Block Protection and ASP protection settings for each sector are logically OR’d to define the protection for
each sector, i.e. if either mechanism is protecting a sector the sector cannot be programmed or erased. Refer
to Block Protection on page 67 for full details of the BP2-0 bits.
Figure 9.1 Advanced Sector Protection Overview
ASP Register
One Time Programmable
Password Method Persistent Method
(ASPR[2]=0)
(ASPR[1]=0)
6.) Password Method requires a
password to set PPB Lock to “1”
to enable program or erase of
PPB bits
Memory Array
Sector 0
Sector 1
Sector 2
64-bit Password
(One Time Protect)
7.) Persistent Method only allows
PPB Lock to be cleared to “0” to
prevent program or erase of PPB
bits. Power off or hardware reset
required to set PPB Lock to “1”
PBB Lock Bit
“0” = PPBs locked
“1”=PPBs unlocked
4.) PPB Lock bit is volatile and
defaults to “1” (persistent
mode).or “0” (password mode)
upon reset
5.) PPB Lock = “0” locks all PPBs
to their current state
Persistent
Dynamic
Protection Bits
Protection Bits
(PPB)
(DYB)
PPB 0
DYB 0
PPB 1
DYB 1
PPB 2
DYB 2
Sector N -2
Sector N -1
Sector N
1.) N = Highest Address Sector,
a sector is protected if its PPB =”0”
or its DYB = “0”
PPB N-2
PPB N-1
PPB N
DYB N-2
DYB N-1
DYB N
2.) PPB are programmed individually ^{3.) DYB are volatile bits}
but erased as a group
Every main flash array sector has a non-volatile (PPB) and a volatile (DYB) protection bit associated with it.
When either bit is 0, the sector is protected from program and erase operations.
The PPB bits are protected from program and erase when the PPB Lock bit is 0. There are two methods for
managing the state of the PPB Lock bit, Persistent Protection and Password Protection.
The Persistent Protection method sets the PPB Lock bit to 1 during POR, or Hardware Reset so that the PPB
bits are unprotected by a device reset. There is a command to clear the PPB Lock bit to 0 to protect the PPB.
There is no command in the Persistent Protection method to set the PPB Lock bit to 1, therefore the PPB
Lock bit will remain at 0 until the next power-off or hardware reset. The Persistent Protection method allows
boot code the option of changing sector protection by programming or erasing the PPB, then protecting the
PPB from further change for the remainder of normal system operation by clearing the PPB Lock bit to 0. This
is sometimes called Boot-code controlled sector protection.
The Password method clears the PPB Lock bit to 0 during POR, or Hardware Reset to protect the PPB. A 64
bit password may be permanently programmed and hidden for the password method. A command can be
used to provide a password for comparison with the hidden password. If the password matches, the PPB
Lock bit is set to 1 to unprotect the PPB. A command can be used to clear the PPB Lock bit to 0. This method
requires use of a password to control PPB protection.
68
S25FL128S and S25FL256S
S25FL128S_256S_00_05 July 12, 2012