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LH75400/01/10/11 (Preliminary) User’s Guide
Static Memory Controller
6/17/03
7-9
7.2.5 External Bus Read/Write Operations
Table 7-3 and Table 7-4 show how the SMC places data from the external bus onto the
AHB based on the specified AHB control signals. Table 7-5 and Table 7-6 show how the
SMC places data onto the external data bus and exercises the nBLE[1:0] signals based
on the AHB control signals. During reads, the nBLE[1:0] signals are both LOW or HIGH,
depending on the SMC configuration.
Table 7-3. 8-bit External Bus Read
ACCESS: READ, 8-BIT EXTERNAL BUS
EXTERNAL DATA MAPPING
ONTO AHB DATA BUS
INTERNAL
TRANSFER
WIDTH
HSIZE[1:0]
HADDR[1:0]
A[1:0]
31:24
23:16
15:8
7:0
Word
(4 transfers)
10
10
10
10
xx
xx
xx
xx
11
10
01
00
7:0
—
—
—
—
7:0
—
—
—
—
7:0
—
—
—
—
7:0
Halfword
(2 transfers)
01
1x
11
10
7:0
—
—
7:0
—
—
—
—
Halfword
(2 transfers)
01
0x
01
00
—
—
—
—
7.0
—
—
Byte
00
11
11
7:0
—
—
—
Byte
00
10
10
—
7:0
—
—
Byte
00
01
01
—
—
7:0
—
Byte
00
00
00
—
—
—
7:0
Table 7-4. 16-bit External Bus Read
ACCESS: READ, 8-BIT EXTERNAL BUS
EXTERNAL DATA MAPPING
ONTO AHB DATA BUS
INTERNAL
TRANSFER
WIDTH
HSIZE[1:0]
HADDR[1:0]
A[1:0]
31:24
23:16
15:8
7:0
Word
(2 transfers)
10
10
xx
xx
1x
0x
15:8
—
7:0
—
—
15:8
—
7:0
Halfword
01
1x
1x
15:8
7:0
—
—
Halfword
01
0x
0x
—
—
15:8
7:0
Byte
00
11
1x
15:8
—
—
—
Byte
00
10
1x
—
7:0
—
—
Byte
00
01
0x
—
—
15:8
—
Byte
00
00
0x
—
—
—
7:0