E
SMART 5 BOOT BLOCK MEMORY FAMILY
operation has completed, the device remains in
read status register mode. From this mode any of
the other read or write modes can be reached with
the appropriate command. For example, to read
data, issue the Read Array command. Additional
Program or Erase commands can also be issued
from this state.
3.0 PRINCIPLES OF OPERATION
The system processor accesses the Smart 5 boot
block memories through the Command User
Interface (CUI), which accepts commands written
with standard microprocessor write timings and
TTL-level control inputs. The flash can be switched
into each of its three read and two write modes
During program or erase operations, the array data
is not available for reading or code execution,
except during an erase suspend. Consequently, the
software that initiates and polls progress of program
and erase operations must be copied to and
executed from system RAM during flash memory
update. After successful completion, reads are
again possible via the Read Array command.
through commands issued to the CUI.
comprehensive chart showing the state transitions
is in Appendix A.
A
After initial device power-up or return from deep
power-down mode, the device defaults to read
array mode. In this mode, manipulation of the
memory control pins allows array read, standby,
and output disable operations. The other read
modes, read identifier and read status register, can
be reached by issuing the appropriate command to
the CUI. Array data, identifier codes and status
register results can be accessed using these
commands independently from the VPP voltage.
Read identifier mode can also be accessed by
PROM programming equipment by raising A9 to
high voltage (VID).
Each of the device modes will be discussed in
detail in the following sections.
3.1
Bus Operations
The local CPU reads and writes flash memory in-
system. All bus cycles to or from the flash memory
conform to standard microprocessor bus cycles.
Four control pins dictate the data flow in and out of
the component: CE#, OE#, WE#, and RP#. These
bus operations are summarized in Tables 3 and 4.
CUI commands sequences also control the write
functions of the flash memory, Program and Erase.
Issuing program or erase command sequences
internally latches addresses and data and initiates
Write State Machine (WSM) operations to execute
the requested write function. The WSM internally
regulates the program and erase algorithms,
including pulse repetition, internal verification, and
margining of data, freeing the host processor from
these tasks and allowing precise control for high
reliability. To execute Program or Erase
commands, VPP must be at valid write voltage (5 V
or 12 V).
3.1.1
READ
The flash memory has three read modes available,
read array, read identifier, and read status. These
read modes are accessible independent of the VPP
voltage. RP# can be at either VIH or VHH. The
appropriate read-mode command must be issued to
the CUI to enter the corresponding mode. Upon
initial device power-up or after exit from deep
power-down mode, the device automatically
defaults to read array mode.
While the WSM is executing a program operation,
the device defaults to the read status register mode
and all commands are ignored. Thus during the
programming process, only status register data can
be accessed from the device. While the WSM is
CE# and OE# must be driven active to obtain data
at the outputs. CE# is the device selection control,
and, when active, enables the selected memory
device. OE# is the data output (DQ0–DQ15) control
and when active drives the selected memory data
onto the I/O bus. In read modes, WE# must be at
VIH and RP# must be at VIH or VHH. Figure 15
illustrates a read cycle.
executing
a erase operation, the device also
defaults to the read status register mode but one
additional command is available, erase suspend to
read, which will suspend the erase operation and
allow reading of array data. The suspended erase
operation can be completed by issuing the Erase
Resume command. After the program or erase
13
ADVANCE INFORMATION
INTEL [ INTEL ]
