FLASH
AS29F040
TM
WRITE OPERATION STATUS
DQ6: Toggle Bit I
The device provides several bits to determine the status of a
Toggle bit I on DQ6 indicates whether an Embedded
write operation: DQ2, DQ3, DQ5, DQ6, and DQ7. Table 5 and Program or Erase algorithm is in progress or complete, or
the following subsections describe the functions of these bits. whether the device has entered the Erase Suspend mode.
DQ7 and DQ6 each offer a method for determining whether a Toggle Bit I may be read at any address, and is valid after the
program or erase operation is complete or in progress. These rising edge of the final WE\ pulse in the command sequence
three bits are discussed first.
(prior to the program or erase operation), and during the sector
erase time-out.
During an Embedded Program or Erase algorithm
operation, successive read cycles to any address cause DQ6
DQ7: Data\ Polling
The Data\ Polling bit, DQ7, indicates to the host system
whether an Embedded Algorithm is in progress or completed,
or whether the device is in Erase Suspend. Data\ Polling is
valid after the rising edge of the final WE\ pulse in the program
or erase command sequence.
FIGURE 3: DATA\ POLLING ALGORITHM
During the Embedded Program algorithm, the device
outputs on DQ7 the complement of the datum programmed
to DQ7. This DQ7 status also applies to programming during
Erase Suspend. When the Embedded Program algorithm
is complete, the device outputs the datum programmed to
DQ7. The system must provide the program address to read
valid status information on DQ7. If a program address falls
within a protected sector, Data\ Polling on DQ7 is active for
approximately 2µs, then the device returns to reading array
data.
During the Embedded Erase algorithm, Data\ Polling
produces a “0” on DQ7. When the Embedded Erase algorithm
is complete, or if the device enters the Erase Suspend mode,
Data\ Polling produces a “1” on DQ7. This is analogous
to the complement/true datum output described for the
Embedded Program algorithm: the erase function changes all
the bits in a sector to “1”; prior to this, the device outputs the
“complement,” or “0”. The system must provide an address
within any of the sectors selected for erasure to read valid status
information on DQ7.
After an erase command sequence is written, if all sectors
selected for erasing are protected, Data\ Polling on DQ7 is
active for approximately 100µs, then the device returns to
reading array data. If not all selected sectors are protected,
the Embedded Erase algorithm erases the unprotected sectors,
and ignores the selected sectors that are protected.
When the system detects DQ7 has changed from the
complement to true data, it can read valid data at DQ7-DQ0
on the following read cycles. This is because DQ7 may
change asynchronously with DQ0-DQ6 while Output Enable
(OE\) is asserted low. The Data\ Polling Timings (During
Embedded Algorithms) figure in the “AC Characteristics” section
illustrates this.
Table 5 shows the outputs for Data\ Polling on DQ7.
Figure 3 shows the Data\ Polling algorithm.
NOTE:
1) VA = Valid address for programming. During a sector erase opera-
tion, a valid address is an address within any sector selected for erasure.
During chip erase, a valid address is any non-protected sector address.
2) DQ7 should be rechecked even if DQ5 = “1” because DQ7 may change
simultaneously with DQ5.
Micross Components reserves the right to change products or specifications without notice.
AS29F040 • Rev. 3.1 07/19
10
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