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A29L004 View Datasheet(PDF) - AMIC Technology

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A29L004 Datasheet PDF : 39 Pages
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RY/BY : Read/Busy (N/A on 32-pin PLCC & (s)TSOP
packages)
The RY/ BY is a dedicated, open-drain output pin that
indicates whether an Embedded algorithm is in progress or
complete. The RY/ BY status is valid after the rising edge of
the final WE pulse in the command sequence. Since
RY/BY is an open-drain output, several RY/ BY pins can be
tied together in parallel with a pull-up resistor to VCC.
If the output is low (Busy), the device is actively erasing or
programming. (This includes programming in the Erase
Suspend mode.) If the output is high (Ready), the device is
ready to read array data (including during the Erase
Suspend mode), or is in the standby mode.
Table 6 shows the outputs for RY/ BY . Refer to “RESET
Timings”, “Timing Waveforms for Program Operation” and
“Timing Waveforms for Chip/Sector Erase Operation” for
more information.
I/O6: Toggle Bit I
Toggle Bit I on I/O6 indicates whether an Embedded
Program or Erase algorithm is in progress or complete, or
whether the device has entered the Erase Suspend mode.
Toggle Bit I may be read at any address, and is valid after
the rising edge of the final WE pulse in the command
sequence (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 I/O6 to toggle.
(The system may use either OE or CE to control the read
cycles.) When the operation is complete, I/O6 stops toggling.
After an erase command sequence is written, if all sectors
selected for erasing are protected, I/O6 toggles for
approximately 100µs, then 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.
The system can use I/O6 and I/O2 together to determine
whether a sector is actively erasing or is erase-suspended.
When the device is actively erasing (that is, the Embedded
Erase algorithm is in progress), I/O6 toggles. When the
device enters the Erase Suspend mode, I/O6 stops toggling.
However, the system must also use I/O2 to determine which
sectors are erasing or erase-suspended. Alternatively, the
system can use I/O7 (see the subsection on " I/O7 : Data
Polling").
If a program address falls within a protected sector, I/O6
toggles for approximately 2µs after the program command
sequence is written, then returns to reading array data.
I/O6 also toggles during the erase-suspend-program mode,
and stops toggling once the Embedded Program algorithm
is complete.
The Write Operation Status table shows the outputs for
Toggle Bit I on I/O6. Refer to Figure 6 for the toggle bit
algorithm, and to the Toggle Bit Timings figure in the "AC
Characteristics" section for the timing diagram. The I/O2 vs.
I/O6 figure shows the differences between I/O2 and I/O6 in
graphical form. See also the subsection on " I/O2: Toggle Bit II".
A29L004 Series
I/O2: Toggle Bit II
The "Toggle Bit II" on I/O2, when used with I/O6, 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.
I/O2 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 I/O2 cannot distinguish whether the sector is
actively erasing or is erase-suspended. I/O6, 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 Table 6 to compare
outputs for I/O2 and I/O6.
Figure 6 shows the toggle bit algorithm in flowchart form,
and the section " I/O2: Toggle Bit II" explains the algorithm.
See also the " I/O6: Toggle Bit I" subsection. Refer to the
Toggle Bit Timings figure for the toggle bit timing diagram.
The I/O2 vs. I/O6 figure shows the differences between I/O2
and I/O6 in graphical form.
Reading Toggle Bits I/O6, I/O2
Refer to Figure 6 for the following discussion. Whenever the
system initially begins reading toggle bit status, it must read
I/O7 - I/O0 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 I/O7 - I/O0 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 I/O5 is high (see the
section on I/O5). 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 I/O5 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 I/O5 has not
gone high. The system may continue to monitor the toggle
bit and I/O5 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 6).
PRELIMINARY (October, 2002, Version 0.0)
17
AMIC Technology, Corp.
 

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