SMART 3 ADVANCED BOOT BLOCK
3.2.3 READ STATUS REGISTER
The device status register indicates when
program or erase operation is complete and the
success or failure of that operation. To read the
status register issue the Read Status Register
(70H) command to the CUI. This causes all
subsequent read operations to output data from the
status register until another command is written to
the CUI. To return to reading from the array, issue
the Read Array (FFH) command.
E
3.2.4
PROGRAM MODE
a
Programming is executed using
a
two-write
sequence. The Program Setup command (40H) is
written to the CUI followed by a second write which
specifies the address and data to be programmed.
The WSM will execute a sequence of internally
timed events to program desired bits of the
addressed location, then Verify the bits are
sufficiently programmed. Programming the memory
results in specific bits within an address location
being changed to a “0.” If the user attempts to
program “1”s, the memory cell contents do not
change and no error occurs.
The status register bits are output on DQ0–DQ7.
The upper byte, DQ8–DQ15, outputs 00H during a
Read Status Register command.
The status register indicates programming status:
while the program sequence executes, status bit 7
is “0.” The status register can be polled by toggling
either CE# or OE#. While programming, the only
valid commands are Read Status Register,
Program Suspend, and Program Resume.
The contents of the status register are latched on
the falling edge of OE# or CE#. This prevents
possible bus errors which might occur if status
register contents change while being read. CE# or
OE# must be toggled with each subsequent status
read, or the status register will not indicate
completion of a program or erase operation.
When programming is complete, the Program
Status bits should be checked. If the programming
operation was unsuccessful, bit SR.4 of the status
register is set to indicate a program failure. If SR.3
is set then VPP was not within acceptable limits, and
the WSM did not execute the program command. If
SR.1 is set, a program operation was attempted on
a locked block and the operation was aborted.
When the WSM is active, SR.7 will indicate the
status of the WSM; the remaining bits in the status
register indicate whether or not the WSM was
successful in performing the desired operation (see
Table 7).
The status register should be cleared before
attempting the next operation. Any CUI instruction
can follow after programming is completed;
however, to prevent inadvertent status register
reads, be sure to reset the CUI to read array mode.
3.2.3.1
Clearing the Status Register
The WSM sets status bits 1 through 7 to “1,” and
clears bits 2, 6 and 7 to “0,” but cannot clear status
bits 1 or 3 through 5 to “0.” Because bits 1, 3, 4 and
5 indicate various error conditions, these bits can
only be cleared through the Clear Status Register
(50H) command. By allowing the system software
to control the resetting of these bits, several
operations may be performed (such as cumulatively
programming several addresses or erasing multiple
blocks in sequence) before reading the status
register to determine if an error occurred during that
series. Clear the status register before beginning
another command or sequence. Note, again, that
the Read Array command must be issued before
data can be read from the memory array.
3.2.4.1
Suspending and Resuming
Program
The Program Suspend halts the in-progress
program operation to read data from another
location of memory. Once the programming process
starts, writing the Program Suspend command to
the CUI requests that the WSM suspend the
program sequence (at predetermined points in the
program algorithm). The device continues to output
status register data after the Program Suspend
command is written. Polling status register bits
SR.7 and SR.2 will determine when the program
operation has been suspended (both will be set to
“1”). tWHRH1/tEHRH1 specify the program suspend
latency.
16
PRELIMINARY
INTEL [ INTEL ]
