S29AS008J datasheet(36/56 Pages) CYPRESS

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Document Number: 002-00870 Rev.*K

Page 36 of 56

S29AS008J

12.3

DQ6: Toggle Bit I

Toggle Bit I on DQ6 indicates whether an Embedded Program or Erase algorithm is in progress or complete, or whether the device

has entered the Erase Suspend mode. Toggle Bit I may be read at any address, and is valid after the rising edge of the final WE#

pulse in the command sequence (prior to the program or erase operation), and during the sector erase time-out.

During an Embedded Program or Erase algorithm operation, successive read cycles to any address cause DQ6 to toggle. (The

system may use either OE# or CE# to control the read cycles.) When the operation is complete, DQ6 stops toggling.

After an erase command sequence is written, if all sectors selected for erasing are protected, DQ6 toggles for approximately 100 µs,

then returns to reading array data. If not all selected sectors are protected, the Embedded Erase algorithm erases the unprotected

sectors, and ignores the selected sectors that are protected.

The system can use DQ6 and DQ2 together to determine whether a sector is actively erasing or is erase-suspended. When the

device is actively erasing (that is, the Embedded Erase algorithm is in progress), DQ6 toggles. When the device enters the Erase

Suspend mode, DQ6 stops toggling. However, the system must also use DQ2 to determine which sectors are erasing or erase-

suspended. Alternatively, the system can use DQ7 (see DQ7: Data# Polling on page 34).

If a program address falls within a protected sector, DQ6 toggles for approximately 1 µs after the program command sequence is

written, then returns to reading array data.

DQ6 also toggles during the erase-suspend-program mode, and stops toggling once the Embedded Program algorithm is complete.

Table on page 38 shows the outputs for Toggle Bit I on DQ6. Figure 12.2 on page 37 shows the toggle bit algorithm in flowchart

form, and Reading Toggle Bits DQ6/DQ2 on page 37 explains the algorithm. Figure 18.8 on page 47 shows the toggle bit timing

diagrams. Figure 18.9 on page 47 shows the differences between DQ2 and DQ6 in graphical form. See also DQ2: Toggle Bit II

on page 36.

12.4

DQ2: Toggle Bit II

The “Toggle Bit II” on DQ2, when used with DQ6, indicates whether a particular sector is actively erasing (that is, the Embedded

Erase algorithm is in progress), or whether that sector is erase-suspended. Toggle Bit II is valid after the rising edge of the final WE#

pulse in the command sequence.

DQ2 toggles when the system reads at addresses within those sectors that have been selected for erasure. (The system may use

either OE# or CE# to control the read cycles.) But DQ2 cannot distinguish whether the sector is actively erasing or is erase-

suspended. DQ6, by comparison, indicates whether the device is actively erasing, or is in Erase Suspend, but cannot distinguish

which sectors are selected for erasure. Thus, both status bits are required for sector and mode information. Refer to Table

on page 38 to compare outputs for DQ2 and DQ6.

Figure 12.2 on page 37 shows the toggle bit algorithm in flowchart form, and the section Reading Toggle Bits DQ6/DQ2 on page 37

explains the algorithm. See also DQ6: Toggle Bit I on page 36. Figure 18.8 on page 47 shows the toggle bit timing diagram.

Figure 18.9 on page 47 shows the differences between DQ2 and DQ6 in graphical form.

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