S71PL254 datasheet(78/196 Pages) SPANSION

78 / 196 page

S29PL127J/S29PL064J/S29PL032J for MCP

S29PL127J_064J_032J_MCP_00_A3 August 12, 2004

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I n f o rmation

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 19 to compare outputs for DQ2 and DQ6.

Figure 7 shows the toggle bit algorithm in flowchart form, and the DQ2: Toggle

Bit II explains the algorithm. See also the DQ6: Toggle Bit I. Figure 19 shows the

toggle bit timing diagram. Figure 20 shows the differences between DQ2 and DQ6

in graphical form.

Reading Toggle Bits DQ6/DQ2

Refer to Figure 7 for the following discussion. Whenever the system initially be-

gins reading toggle bit status, it must read DQ7–DQ0 at least twice in a row to

determine whether a toggle bit is toggling. Typically, the system would note and

Note: The system should recheck the toggle bit even if DQ5 = “1” because the toggle

bit may stop toggling as DQ5 changes to “1.” See the DQ6: Toggle Bit I and DQ2:

Toggle Bit II for more information.

Figure 7. Toggle Bit Algorithm

START

Yes

DQ5 = 1?

Yes

Toggle Bit

= Toggle?

Program/Erase

Operation Not

Complete, Write

Reset Command

Program/Erase

Operation Complete

Toggle Bit

= Toggle?

Read Byte Twice

(DQ7–DQ0)

Address = VA

Read Byte

(DQ7–DQ0)

Address =VA

Read Byte

(DQ7–DQ0)

Address =VA

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