EN29F040 Datasheet, PDF (11/32 Pages) List of Unclassifed Manufacturers – 4 Megabit (512K x 8-bit) Flash Memory

EN29F040
WRITE OPERATION STATUS
DQ7
DATA Polling
The EN29F040 provides DATA Polling on DQ7 to indicate to the host system the status of the
embedded operations. The DATA Polling feature is active during the Byte Programming, Sector
Erase, Chip Erase, and Erase Suspend. (See Table 6)
When the Byte Programming is in progress, an attempt to read the device will produce the
complement of the data last written to DQ7. Upon the completion of the Byte Programming, an
attempt to read the device will produce the true data last written to DQ7. For the Byte Programming,
DATA polling is valid after the rising edge of the fourth WE or CE pulse in the four-cycle sequence.
When the embedded Erase is in progress, an attempt to read the device will produce a “0” at the
DQ7 output. Upon the completion of the embedded Erase, the device will produce the “1” at the DQ7
output during the read. For Chip Erase, the DATA polling is valid after the rising edge of the sixth
W E or CE pulse in the six-cycle sequence. For Sector Erase, DATA polling is valid after the last
rising edge of the sector erase W E or C E pulse.
DATA Polling must be performed at any address within a sector that is being programmed or erased
and not a protected sector. Otherwise, DATA polling may give an inaccurate result if the address
used is in a protected sector.
Just prior to the completion of the embedded operations, DQ7 may change asynchronously when the
output enable ( OE ) is low. This means that the device is driving status information on DQ7 at one
instant of time and valid data at the next instant of time. Depending on when the system samples the
DQ7 output, it may read the status of valid data. Even if the device has completed the embedded
operations and DQ7 has a valid data, the data output on DQ0-DQ6 may be still invalid. The valid
data on DQ0-DQ7 will be read on the subsequent read attempts.
The flowchart for DATA Polling (DQ7) is shown on Flowchart 5. The DATA Polling (DQ7) timing
diagram is shown in Figure 8.
DQ6
Toggle Bit I
The EN29F040 provides a “Toggle Bit” on DQ6 to indicate to the host system the status of the
embedded programming and erase operations. (See Table 6)
During an embedded Program or Erase operation, successive attempts to read data from the device
at any address (by toggling OE or CE ) will result in DQ6 toggling between “zero” and “one”. Once
the embedded Program or Erase operation is complete, DQ6 will stop toggling and valid data will be
read on the next successive attempts. During Byte Programming, the Toggle Bit is valid after the
rising edge of the fourth WE pulse in the four-cycle sequence. For Chip Erase, the Toggle Bit is valid
after the rising edge of the sixth-cycle sequence. For Sector Erase, the Toggle Bit is valid after the
last rising edge of the Sector Erase W E pulse. The Toggle Bit is also active during the sector erase
time-out window.
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Rev. D, Issue Date: 2001/07/05
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