S29GL01GS10TFI010 Datasheet, PDF (41/104 Pages) SPANSION – GL-S MirrorBit Eclipse Flash Non-Volatile Memory Family

Data Sheet
5.4.2.5
Reading Toggle Bits DQ6/DQ2
Refer to Figure 5.5 on page 39 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, the 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 previous value. If the toggle bit is not
toggling, the device has completed the program or erases operation. The system can read array data on
DQ15-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 should note whether the value of DQ5 is High (see DQ5: Exceeded Timing Limits on page 41). 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.
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, it 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 (top of Figure 5.6 on page 41).
Figure 5.6 Toggle Bit Program
START
Read DQ7 -DQ0
Read DQ7 -DQ0 (Note 1)
Toggle Bit
No
= Toggle?
Yes
No
DQ5 = 1?
Yes
Read DQ7 -DQ0 Twice (Notes 1, 2)
5.4.2.6
Toggle Bit
= Toggle?
Yes
Erase/Program
Operation Not
Complete
No
Erase/Program
Operation Complete
Notes:
1. Read toggle bit twice to determine whether or not it is toggling. See text.
2. Recheck toggle bit because it may stop toggling as DQ5 changes to 1. See text.
DQ5: Exceeded Timing Limits
DQ5 indicates whether the program or erase time has exceeded a specified internal pulse count limit. Under
these conditions DQ5 produces a 1. This is a failure condition that indicates the program or erase cycle was
not successfully completed. The system must issue the reset command to return the device to reading array
data.
When a timeout occurs, the software must send a reset command to clear the timeout bit (DQ5) and to return
the EAC to read array mode. In this case, it is possible that the flash will continue to communicate busy for up
to 2 µs after the reset command is sent.
December 21, 2012 S29GL_128S_01GS_00_07
GL-S MirrorBit^® Family
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