LHF00L02 6
2 Device Operation
2.1 Mode Selection
The product can operate in two distinct interface modes:
• The LPC interface mode for In-System erasing and
programming
• Address/Address Multiplexed (A/A) interface mode
for factory erasing and programming
The state of the device’s MODE pin determines which
interface is in use. If the MODE pin is set to logic high,
the device is in A/A mode; while if the MODE pin is set
low, the device is in the LPC mode. The MODE selection
pin must be configured prior to device operation.
2.2 LPC Mode
The LPC mode uses a 5-signal communication interface,
4-bit address/data bus, LAD3-LAD0, and a control line,
LFRAME#, to control operations of the product. Cycle
type operations such as Memory Read and Memory Write
are defined in Intel Low Pin Count Interface
Specification, Rev.1.0. Erase and Program commands
sequences are incorporated into the standard LPC
memory cycles.
LPC signals are transmitted via the 4-bit Address/Data
bus (LAD3-LAD0), and follow a particular sequence,
depending on whether they are Read or Write operations.
The standard LPC memory cycle is defined in Table 2 and
Table 3.
2.2.1 CE#, LFRAME#
The CE# pin, enables and disables the product,
controlling read and write access of the device. To enable
the product, the CE# pin must be driven low one cycle
prior to LFRAME# being driven low. For write (erase or
program) cycles, the CE# pin must remain low during the
internal operation. When CE# is high, the product is
placed in standby mode.
The LFRAME# signifies the start of a frame or the
termination of a broken frame. Asserting LFRAME# for
one or more clock cycle and driving a valid "START"
value on LAD3-LAD0 will initiate device operation. The
device enters standby mode when LFRAME# and CE#
are high and no internal operation is in progress.
2.2.2 Abort Mechanism
If LFRAME# is driven low for 4 clock cycles during a
LPC cycle, the cycle will be terminated and the device
will wait for the "ABORT" command. To return the
device to the ready mode, the host must drive the LAD3-
LAD0 with "1111b" ("ABORT" command) while
LFRAME# is driven low, and LAD3-LAD0 must remain
unchanged until LFRAME# goes to VIH (refer to Figure
18). When an abort procedure is performed between the
two command write cycles, such as sector/block erase or
byte program, the device turns the bus around to the host
but the termination of command for the internal operation
is not guaranteed. If the system needs to abort after the
first command cycle, the host must write "FFH" and
check the status register after performing the abort
procedure. Status register indicates the termination of
internal operation and error conditions. If abort occurs
during the internal write cycle, the data may be
incorrectly programmed or erased. It is required to wait
for the write operation to complete prior to initiation of
the abort command. It is recommended to check the write
status with status polling (DQ7) or toggle bit (DQ6). One
other option is to wait for the fixed write time to expire.
2.3 Status Polling DQ7
(LPC Mode, A/A Mode)
When the product device is in the automatic internal
operation (program, erase, etc.), WSM (Write State
Machine) status bit DQ7 (SR.7) will produce a "0". Once
the internal operation is completed, DQ7 will produce a
"1". The SR.7 bit can be polled to find the end of the
operation. The other status bits (SR.5-0) should not be
checked until the WSM completes the operation and the
status bit SR.7 is "1". Refer to Table 13 for the status
register definition.
Rev. 0.05