Table 10. Configuration Register After Device Reset
CR15
RM
1
CR14
Reserve
0
CR13
IAD3
0
CR12
IAD2
1
CR11
IAD1
1
CR10
IAD0
1
CR9
DOC
0
CR8
WC
0
CR7
BS
1
CR6
CC
1
CR5
Reserve
0
CR4
Reserve
0
CR3
Reserve
0
CR2
BL2
1
CR1
BL1
0
CR0
BL0
0
driven active before data will be available. This value
is determined by the input clock frequency.
Initial Access Delay Configuration
The frequency configuration informs the device of the
number of clocks that must elapse after ADV# is
SECTOR PROTECTION
The Am29BDD160 features several levels of sector
protection, which can disable both the program and
erase operations in certain sectors or sector groups
they must set the Persistent Sector Protection
Mode Locking Bit. This will permanently set the part
to operate only using Persistent Sector Protection. If
the customer decides to use the password method,
they must set the Password Mode Locking Bit. This
will permanently set the part to operate only using
password sector protection.
Sector and Sector Groups
The distinction between sectors and sector groups is
fundamental to sector protection. Sector are individual
sectors that can be individually sector protected/un-
protected. These are the outermost 4 kword boot sec-
tors, that is, SA0 to SA7 and SA38 to SA45. See
tables 11 and 12.
It is important to remember that setting either the Per-
sistent Sector Protection Mode Locking Bit or the
Password Mode Locking Bit permanently selects
the protection mode. It is not possible to switch be-
tween the two methods once a locking bit has been
set. It is important that one mode is explicitly se-
lected when the device is first programmed, rather
than relying on the default mode alone. This is so
that it is not possible for a system program or virus to
later set the Password Mode Locking Bit, which would
cause an unexpected shift from the default Persistent
Sector Protection Mode into the Password Protection
Mode.
Sector groups are a collection of three or four adjacent
32 kword sectors. For example, sector group SG8 is
comprised of sector SA8 to SA10. When any sector in
a sector group is protected/unprotected, every sector
in that group is protection/unprotected. See Tables 11
and 12.
Persistent Sector Protection
A command sector protection method that replaces
the old 12 V controlled protection method.
The WP# Hardware Protection feature is always avail-
able, independent of the software managed protection
method chosen.
Password Sector Protection
A highly sophisticated protection method that requires
a password before changes to certain sectors or sec-
tor groups are permitted
Persistent Sector Protection
The Persistent Sector Protection method replaces the
old 12 V controlled protection method while at the
same time enhancing flexibility by providing three dif-
ferent sector protection states:
WP# Hardware Protection
A write protect pin that can prevent program or erase
to the two outermost 8 Kbytes sectors in the 75% bank
All parts default to operate in the Persistent Sector
Protection mode. The customer must then choose if
the Persistent or Password Protection method is most
desirable. There are two one-time programmable
non-volatile bits that define which sector protection
method will be used. If the customer decides to con-
tinue using the Persistent Sector Protection method,
■ Persistently Locked—A sector is protected and
cannot be changed.
■ Dynamically Locked—The sector is protected and
can be changed by a simple command
■ Unlocked—The sector is unprotected and can be
changed by a simple command
24
Am29BDD160G
June 7, 2006
SPANSION [ SPANSION ]
