A D V A N C E I N F O R M A T I O N
(During Embedded Algorithm),” on page 55 (toggle bit
RDY: Ready
timing diagram), and Table 15, “DQ6 and DQ2 Indica-
tions,” on page 32.
The RDY is a dedicated output that, by default, indi-
cates (when at logic low) the system should wait 1
clock cycle before expecting the next word of data.
Using the RDY Configuration Command Sequence,
RDY can be set so that a logic low indicates the system
should wait 2 clock cycles before expecting valid data.
START
RDY functions only while reading data in burst mode.
The following conditions cause the RDY output to be
low: during the initial access (in burst mode), and after
the boundary that occurs every 64 words beginning
with the 64th address, 3Fh.
Read Byte
DQ7–DQ0
Address = VA
Read Byte
DQ7–DQ0
Address = VA
DQ6: Toggle Bit I
Toggle Bit I on DQ6 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 in the
same bank, 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.
No
DQ6 = Toggle?
Yes
During an Embedded Program or Erase algorithm
operation, successive read cycles to any address
cause DQ6 to toggle. When the operation is complete,
DQ6 stops toggling.
No
DQ5 = 1?
Yes
After an erase command sequence is written, if all
sectors selected for erasing are protected, DQ6
toggles for approximately 100 µs, then returns to
reading array data. If not all selected sectors are pro-
tected, the Embedded Erase algorithm erases the
unprotected sectors, and ignores the selected sectors
that are protected.
Read Byte Twice
DQ7–DQ0
Address = VA
No
DQ6 = Toggle?
The system can use DQ6 and DQ2 together to deter-
mine 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),
DQ6 toggles. When the device enters the Erase
Suspend mode, DQ6 stops toggling. However, the
system must also use DQ2 to determine which sectors
are erasing or erase-suspended. Alternatively, the
system can use DQ7 (see the subsection on DQ7:
Data# Polling).
Yes
FAIL
PASS
Note: The system should recheck the toggle bit even if DQ5
= “1” because the toggle bit may stop toggling as DQ5
changes to “1.” See the subsections on DQ6 and DQ2 for
more information.
If a program address falls within a protected sector,
DQ6 toggles for approximately 1 ms after the program
command sequence is written, then returns to reading
array data.
Figure 5. Toggle Bit Algorithm
DQ6 also toggles during the erase-suspend-program
mode, and stops toggling once the Embedded
Program algorithm is complete.
DQ2: Toggle Bit II
See the following for additional information: Figure 4
(toggle bit flowchart), DQ6: Toggle Bit I (description),
The “Toggle Bit II” on DQ2, when used with DQ6, indi-
cates whether a particular sector is actively erasing
(that is, the Embedded Erase algorithm is in progress),
Figure 28,
“Toggle
Bit
Timings
October 31, 2002
Am29BDS640G
31
SPANSION [ SPANSION ]
