DS42515 AMD, DS42515 Datasheet - Page 15

• Manufacturer Part Number: DS42515
• Description: MCP Flash Memory and SRAM
• Manufacturer: AMD

Autoselect Mode
The autoselect mode provides manufacturer and de-
vice identification, and sector protection verification,
through identifier codes output on DQ7–DQ0. This
mode is primarily intended for programming equip-
m e n t t o a u t o m a t i c a l l y m a t c h a d e v i c e t o b e
programmed with its corresponding programming al-
gorithm. However, the autoselect codes can also be
accessed in-system through the command register.
To access the autoselect codes in-system, the host
system can issue the autoselect command via the
command register, as shown in Table 12. This method
does not require V
mand Sequence section for more information.
Sector/Sector Block Protection and
Unprotection
(Note: For the following discussion, the term “sector”
applies to both sectors and sector blocks. A sector
block consists of two or more adjacent sectors that are
protected or unprotected at the same time (see Table
7).
The hardware sector protection feature disables both
program and erase operations in any sector. The hard-
ware sector unprotection feature re-enables both
program and erase operations in previously protected
sectors. Sector protection and unprotection can be im-
plemented as follows.
Sector / Sector
Table 7. Bottom Boot Sector/Sector Block
SA37-SA35
SA34-SA31
SA30-SA27
SA26-SA23
SA22-SA19
SA18-SA15
SA14-SA11
SA10-SA8
Addresses for Protection/Unprotection
Block
SA38
SA7
SA6
SA5
SA4
SA3
SA2
SA1
SA0
ID
101XXXXX
100XXXXX
010XXXXX
001XXXXX
00001XXX,
00010XXX,
11110XXX,
11101XXX,
110XXXXX
011XXXXX
00011XXX
11111XXX
11100XXX
00000111
00000110
00000101
00000100
00000011
00000010
00000001
00000000
A19–A12
. Refer to the Autoselect Com-
Sector / Sector Block Size
192 (3x64) Kbytes
256 (4x64) Kbytes
256 (4x64) Kbytes
256 (4x64) Kbytes
256 (4x64) Kbytes
256 (4x64) Kbytes
256 (4x64) Kbytes
192 (3x64) Kbytes
64 Kbytes
8 Kbytes
8 Kbytes
8 Kbytes
8 Kbytes
8 Kbytes
8 Kbytes
8 Kbytes
8 Kbytes
DS42515
The sector protection and unprotection requires V
the RESET# pin only, and can be implemented either
in-system or via programming equipment. Figure 2
shows the algorithms and Figure 26 shows the timing
diagram. This method uses standard microprocessor
bus cycle timing. For sector unprotect, all unprotected
sectors must first be protected prior to the first sector
unprotect write cycle. Note that the sector unprotect
algorithm unprotects all sectors in parallel. All previ-
o u s l y p r o t e c t e d s e c t o r s m u s t b e i n d i v i d u a l l y
re-protected. To change data in protected sectors effi-
ciently, the temporary sector unprotect function is
available. See “Temporary Sector/Sector Block
Unprotect”.
The device is shipped with all sectors unprotected.
It is possible to determine whether a sector is pro-
tected or unprotected. See the Autoselect Mode
section for details.
Write Protect (WP#)
The Write Protect function provides a hardware
method of protecting certain boot sectors without
using V
WP#/ACC pin.
If the system asserts V
vice disables program and erase functions in the two
“outermost” 8 Kbyte boot sectors independently of
whether those sectors were protected or unprotected
using the method described in “Sector/Sector Block
Protection and Unprotection”. The two outermost 8
Kbyte boot sectors are the two sectors containing the
lowest addresses in a bottom-boot-configured device,
or the two sectors containing the highest addresses in
a top-boot-configured device.
If the system asserts V
vice reverts to whether the two outermost 8 Kbyte boot
sectors were last set to be protected or unprotected.
That is, sector protection or unprotection for these two
sectors depends on whether they were last protected
or unprotected using the method described in “Sec-
tor/Sector Block Protection and Unprotection”.
Note that the WP#/ACC pin must not be left floating or
unconnected; inconsistent behavior of the device may
result.
Temporary Sector/Sector Block Unprotect
(Note: For the following discussion, the term “sector”
applies to both sectors and sector blocks. A sector
block consists of two or more adjacent sectors that are
protected or unprotected at the same time (see Table
7).
This feature allows temporary unprotection of previ-
ously protected sectors to change data in-system. The
Sector Unprotect mode is activated by setting the RE-
ID
. This function is one of two provided by the
IL
IH
on the WP#/ACC pin, the de-
on the WP#/ACC pin, the de-
ID
15
on