s29cd-j Meet Spansion Inc., s29cd-j Datasheet - Page 37

• Manufacturer Part Number: s29cd-j
• Description: 32/16 Megabit Cmos 2.6 Volt Or 3.3 Volt-only Simultaneous Read/write, Dual Boot, Burst Mode Flash Memory With Versatilei/o?
• Manufacturer: Meet Spansion Inc.

March 7, 2007 S29CD-J_CL-J_00_B2
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
programming in erase
erase suspended,
actively erasing,
programming,
If device is
suspend,
D a t a
S h e e t
at an address within a sector selected
at an address within sectors selected
at an address within sectors not
at an address within secotrs not
S29CD-J & S29CL-J Flash Family
and the system reads
selected for erasure,
selected for erasure,
at any address,
at any address,
( P r e l i m i n a r y )
for erasure,
for erasure,
Table 8.8 DQ6 and DQ2 Indications
Figure 8.8
returns array
then DQ6
does not
toggles,
toggles,
toggles,
toggles,
toggle,
data,
for more on the Toggle Bit Algorithm.
read from any sector not selected for
returns array data. The system can
is not applicable.
does not toggle.
does not toggle
also toggles.
and DQ2
erasure.
toggles.
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