EN29LV320C Datasheet, PDF (23/49 Pages) Eon Silicon Solution Inc. – 32 Megabit (4096K x 8-bit / 2048K x 16-bit) Flash Memory Boot Sector Flash Memory, CMOS 3.0 Volt-only

DQ2: Erase Toggle Bit II
EN29LV320C
The “Toggle Bit” 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 the following
table to compare outputs for DQ2 and DQ6.
Flowchart 6 shows the toggle bit algorithm, and the section “DQ2: Toggle Bit” explains the algorithm.
See also the “DQ6: Toggle Bit I” subsection. Refer to the Toggle Bit Timings figure for the toggle bit
timing diagram. The DQ2 vs. DQ6 figure shows the differences between DQ2 and DQ6 in graphical
form.
Reading Toggle Bits DQ6/DQ2
Refer to Flowchart 6 for the following discussion. Whenever the system initially begins reading toggle
bit status, it must read DQ7–DQ0 at least twice in a row to determine whether a toggle bit is toggling.
Typically, a system would note and store the value of the toggle bit after the first read. After the second
read, the system would compare the new value of the toggle bit with the first. If the toggle bit is not
toggling, the device has completed the program or erase operation. The system can read array data on
DQ7–DQ0 on the following read cycle.
However, after the initial two read cycles, the system determines that the toggle bit is still toggling. And
the system also should note whether the value of DQ5 is high (see the section on DQ5). If it is, the
system should then determine 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 erase operation. If it is still toggling, the device did not complete
the operation successfully, and the system must write the reset command to return to reading array
data.
This Data Sheet may be revised by subsequent versions
23 ^{© 2004 Eon Silicon Solution, Inc.,}
or modifications due to changes in technical specifications.
Rev. B, Issue Date: 2011/05/13
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