AS29CF160T-55TIN
AS29CF160B-55TIN
RY/
: Read/
Busy
BY
I/O2: Toggle Bit II
The RY/
is a dedicated, open-drain output pin that
BY
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
indicates whether an Embedded algorithm is in progress or
complete. The RY/ status is valid after the rising edge of
BY
pulse in the command sequence. Since RY/
the final
WE
BY
pins can be tied
rising edge of the final
pulse in the command sequence.
is an open-drain output, several RY/
BY
together in parallel with a pull-up resistor to VCC.
WE
I/O2 toggles when the system reads at addresses within those
sectors that have been selected for erasure. (The system may
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.
use either
or
to control the read cycles.) But I/O2
CE
OE
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 10 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.
Table 10 shows the outputs for RY/
. Refer to “
RESET
BY
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
Reading Toggle Bits I/O6, I/O2
of the final
pulse in the command sequence (prior to the
WE
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).
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
or
to control the read
CE
OE
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".
I/O5: Exceeded Timing Limits
I/O5 indicates whether the program or erase time has
exceeded a specified internal pulse count limit. Under these
conditions I/O5 produces a "1." This is a failure condition that
indicates the program or erase cycle was not successfully
completed.
Confidential
- 20 of 41 -
Rev.1.0 July 2019
ALSC [ ALLIANCE SEMICONDUCTOR CORPORATION ]
