M50FW002 データシートの表示（PDF） - STMicroelectronics
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M50FW002 Datasheet PDF : 39 Pages
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M50FW002
Table 4. FWH Bus Read Field Definitions
Clock
Cycle
Number
Clock Cycle
Count
Field
FWH0-
FWH3
Memory
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
2
1
IDSEL
XXXX
I
value on FWH0-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.
Indicates how many bytes will be transferred during
10
1
MSIZE
0X0Xb
I
multi-byte read operations. The FWH Flash Memory
supports 1-byte (0000b), 16-byte (0100b) and 32-byte
(0101b) transfers.
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
2
WSYNC 0101b
O
(short wait-sync) for two clock cycles, indicating that the
data is not yet available. Two wait-states are always
included.
The FWH Flash Memory drives FWH0-FWH3 to 0000b,
15
1
RSYNC 0000b
O 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.
17+
5(2n-1)
0 (1-byte)
75 (16-byte)
155 (32-byte)
MULTI-
BYTE
2 WSYNC
+
1 RSYNC
+
2 DATA
For each subsequent byte of data repeat cycles 13-17
O
(2WSYNC + 1RSYNC + 2DATA) 2n-1 times. The FWH
Flash Memory supports n = 0000b (1-byte), n = 0100b
(16-byte) and n = 0101b (32-byte) reads.
Previous
+1
1
TAR
1111b
O
The FWH Flash Memory drives FWH0-FWH3 to 1111b
to indicate a turnaround cycle.
Previous
+1
1
TAR
1111b
(float)
N/A
The FWH Flash Memory floats its outputs, the host
takes control of FWH0-FWH3.
Figure 5. FWH Bus Read Waveforms (1-byte)
CLK
FWH4
FWH0-FWH3
Number of
clock cycles
START
1
IDSEL
1
ADDR
7
MSIZE
1
TAR
2
SYNC
3
DATA
2
TAR
2
AI03437
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