S29CD032J datasheet(40/81 Pages) SPANSION

40 / 81 page

S29CD-J and S29CL-J Flash Family

S29CD-J_CL-J_00_B7 October 11, 2012

Da ta

Sh e e t

8.8.4

Reading Toggle Bits DQ6/DQ2

Whenever the system initially begins reading toggle bit status, it must perform two consecutive reads of DQ7-

DQ0 in a row in order to determine whether a toggle bit is toggling. Typically, the system notes and stores the

value of the toggle bit after the first read. After the second read, the system compares the new value of the

toggle bit with the first. If the toggle bit is not toggling, the device completes the program or erases operation.

The system can read array data on DQ7-DQ0 on the following read cycle.

However, if after the initial two read cycles, the system determines that the toggle bit is still toggling, the

system also notes whether the value of DQ5 is high (see the section on DQ5). If it is, the system then

determines again whether the toggle bit is toggling, since the toggle bit may have stopped toggling just as

DQ5 went high. If the toggle bit is no longer toggling, the device has successfully completed the program or

erases operation. If it is still toggling, the device had not completed the operation successfully, and the

system writes the reset command to return to reading array data.

The remaining scenario is that the system initially determines that the toggle bit is toggling and DQ5 has not

gone high. The system may continue to monitor the toggle bit and DQ5 through successive read cycles,

determining the status as described in the previous paragraph. Alternatively, the system may choose to

perform other system tasks. In this case, the system must start at the beginning of the algorithm when it

returns to determine the status of the operation. Refer to Figure 8.8 for more on the Toggle Bit Algorithm.

Table 8.8 DQ6 and DQ2 Indications

If device is

and the system reads

then DQ6

and DQ2

programming,

at any address,

toggles,

does not toggle.

actively erasing,

at an address within a sector selected

for erasure,

toggles,

also toggles.

at an address within sectors not

selected for erasure,

toggles,

does not toggle

erase suspended,

at an address within sectors selected

for erasure,

does not

toggle,

toggles.

at an address within sectors not

selected for erasure,

returns array

data,

returns array data. The system can

read from any sector not selected for

erasure.

programming in erase

suspend,

at any address,

toggles,

is not applicable.

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