M50FW040 データシートの表示（PDF） - STMicroelectronics
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M50FW040 Datasheet PDF : 41 Pages
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M50FW040
subset of the features available to the Firmware
Hub (FWH) Interface are available; these include
all the Commands but exclude the Security fea-
tures and other registers.
The following operations can be performed using
the appropriate bus cycles: Bus Read, Bus Write,
Output Disable and Reset.
When the Address/Address Multiplexed (A/A Mux)
Interface is selected all the blocks are unprotect-
ed. It is not possible to protect any blocks through
this interface.
Bus Read. Bus Read operations are used to out-
put the contents of the Memory Array, the Elec-
tronic Signature and the Status Register. A valid
Bus Read operation begins by latching the Row
Address and Column Address signals into the
memory using the Address Inputs, A0-A10, and
the Row/Column Address Select RC. Then Write
Enable (W) and Interface Reset (RP) must be
High, VIH, and Output Enable, G, Low, VIL, in order
to perform a Bus Read operation. The Data Inputs/
Outputs will output the value, see Figure 14., A/A
Mux Interface Read AC Waveforms, and Table
22., A/A Mux Interface Read AC Characteristics,
for details of when the output becomes valid.
Bus Write. Bus Write operations write to the
Command Interface. A valid Bus Write operation
begins by latching the Row Address and Column
Address signals into the memory using the Ad-
dress Inputs, A0-A10, and the Row/Column Ad-
dress Select RC. The data should be set up on the
Data Inputs/Outputs; Output Enable, G, and Inter-
face Reset, RP, must be High, VIH and Write En-
able, W, must be Low, VIL. The Data Inputs/
Outputs are latched on the rising edge of Write En-
able, W. See Figure 15., A/A Mux Interface Write
AC Waveforms, and Table 23., A/A Mux Interface
Write AC Characteristics, for details of the timing
requirements.
Output Disable. The data outputs are high-im-
pedance when the Output Enable, G, is at VIH.
Reset. During Reset mode all internal circuits are
switched off, the memory is deselected and the
outputs are put in high-impedance. The memory is
in Reset mode when RP is Low, VIL. RP must be
held Low, VIL for tPLPH. If RP is goes Low, VIL, dur-
ing a Program or Erase operation, the operation is
aborted and the memory cells affected no longer
contain valid data; the memory can take up to tPL-
RH to abort a Program or Erase operation.
Table 4. FWH Bus Read Field Definitions
Clock Clock
Cycle Cycle
Number Count
Field
FWH0- Memory
FWH3 I/O
Description
1
1 START 1101b
I
On the rising edge of CLK with FWH4 Low, the contents of FWH0-
FWH3 indicate the start of a FWH Read cycle.
Indicates which FWH Flash Memory is selected. The value on FWH0-
2
1
IDSEL XXXX
I FWH3 is compared to the IDSEL strapping on the FWH Flash
Memory pins to select which FWH Flash Memory is being addressed.
3-9
7
ADDR XXXX
I
A 28-bit address phase is transferred starting with the most significant
nibble first.
10
1
MSIZE 0000b
I Always 0000b (only single byte transfers are supported).
11
1
TAR 1111b
I The host drives FWH0-FWH3 to 1111b to indicate a turnaround cycle.
12
1
TAR
1111b
(float)
O
The FWH Flash Memory takes control of FWH0-FWH3 during this
cycle.
13-14
The FWH Flash Memory drives FWH0-FWH3 to 0101b (short wait-
2 WSYNC 0101b O sync) for two clock cycles, indicating that the data is not yet available.
Two wait-states are always included.
15
1
RSYNC 0000b
O
The FWH Flash Memory drives FWH0-FWH3 to 0000b, indicating
that data will be available during the next clock cycle.
16-17
2
DATA XXXX
O
Data transfer is two CLK cycles, starting with the least significant
nibble.
18
1
TAR 1111b
O
The FWH Flash Memory drives FWH0-FWH3 to 1111b to indicate a
turnaround cycle.
19
1
TAR
1111b
(float)
N/A
The FWH Flash Memory floats its outputs, the host takes control of
FWH0-FWH3.
12/41
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