S29AS008J datasheet(17/56 Pages) CYPRESS

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Document Number: 002-00870 Rev.*K

Page 17 of 56

S29AS008J

7.12

Temporary Sector Group Unprotect

This feature allows temporary unprotection of previously protected sectors to change data in-system. The Sector Group Unprotect

mode is activated by setting the RESET# pin to VID. During this mode, formerly protected sectors can be programmed or erased by

selecting the sector addresses. Once VID is removed from the RESET# pin, all the previously protected sectors are protected again.

Figure 7.2 shows the algorithm, and Figure 18.10 on page 48 shows the timing diagrams, for this feature. If the WP# pin is at VIL, the

sectors protected by the WP# input will remain protected during the Temporary Sector Group Unprotect mode.

Figure 7.2 Temporary Sector Group Unprotect Operation

Notes

1. All protected sector groups unprotected.

2. All previously protected sector groups are protected once again.

7.13

Write Protect (WP#)

The Write Protect function provides a hardware method of protecting certain boot sectors without using VID. This function is one of

two provided by the WP# pin.

If the system asserts VIL on the WP# pin, the device 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 Section 7.11, Sector

Group Protection/Unprotection on page 15. 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 VIH on the WP# pin, the device reverts to whether the two outermost 8-KByte boot sectors were last set to be

protected or unprotected. That is, sector group protection or unprotection for these two sectors depends on whether they were last

protected or unprotected using the method described in Section 7.11.

The WP# contains an internal pull-up; when unconnected, WP is at VIH.

START

Perform Erase or

Program Operations

RESET# = VIH

Temporary Sector Group

Unprotect Completed

(Note 2)

RESET# = VID

(Note 1)

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