Motorola MPC823e Reference Manual page 333

External Bus Interface
Figure 13-19 illustrates the device connections on the data bus.
OP0
D[0:7]
OP0
OP0
OP2
OP0
OP1
OP2
OP3
Figure 13-19. Interface To Different Port Size Devices
Table 13-2 lists the bytes for read cycles required on the data bus.
Table 13-2. Data Bus Requirements For Read Cycles
TRANSFER TSIZE INTERNAL
SIZE [0:1] ADDRESS
A30
Byte 0 1 0
0 1 0
0 1 1
0 1 1
Half-Word 1 0 0
1 0 1
Word 0 0 0
NOTE: — Denotes that a byte is not required during that read cycle.
13-26
OP1 OP2
D[8:15]
OP1 OP2
OP1
16-BIT PORT SIZE
OP3
8-BIT PORT SIZE
32-BIT PORT SIZE
A31 D0–D7 D8–D15 D16–D23
0 OP0 —
1 — OP1
0 — — OP2
1 — —
0 OP0 OP1
0 — — OP2
0 OP0 OP1 OP2
MPC823e REFERENCE MANUAL
OP3
D[16:23] D[24:31]
OP3 32-BIT PORT SIZE
16-BIT PORT SIZE
D24–D31 D0–D7
— — OP0
— — —
— OP2
— OP3 —
— — OP0
OP3 OP2
OP3 OP0
INTERFACE
OUTPUT
REGISTER
8-BIT
PORT
SIZE
D8–D15 D0–D7
— OP0
OP1 OP1
— OP2
OP3 OP3
OP1 OP0
OP3 OP2
OP1 OP0
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