AM29DL164D datasheet(15/57 Pages) AMD

15 / 57 page

DS42515

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-

ment to autom atic ally ma tch a dev ice to 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

ID. Refer to the Autoselect Com-

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).

Table 7.

Bottom Boot Sector/Sector Block

Addresses for Protection/Unprotection

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.

The sector protection and unprotection requires V

ID on

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-

ous ly pr otected se ctor s must be i ndiv i dua lly

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

ID. This function is one of two provided by the

WP#/ACC pin.

If the system asserts V

IL on the WP#/ACC pin, the de-

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

IH on the WP#/ACC pin, the de-

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-

Sector / Sector

Block

A19–A12

Sector / Sector Block Size

SA38

11111XXX

64 Kbytes

SA37-SA35

11110XXX,

11101XXX,

11100XXX

192 (3x64) Kbytes

SA34-SA31

110XXXXX

256 (4x64) Kbytes

SA30-SA27

101XXXXX

256 (4x64) Kbytes

SA26-SA23

100XXXXX

256 (4x64) Kbytes

SA22-SA19

011XXXXX

256 (4x64) Kbytes

SA18-SA15

010XXXXX

256 (4x64) Kbytes

SA14-SA11

001XXXXX

256 (4x64) Kbytes

SA10-SA8

00001XXX,

00010XXX,

00011XXX

192 (3x64) Kbytes

SA7

00000111

8 Kbytes

SA6

00000110

8 Kbytes

SA5

00000101

8 Kbytes

SA4

00000100

8 Kbytes

SA3

00000011

8 Kbytes

SA2

00000010

8 Kbytes

SA1

00000001

8 Kbytes

SA0

00000000

8 Kbytes

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