Nexus3/ Module
e200z3 Power Architecture Core Reference Manual, Rev. 2
10-18
Freescale Semiconductor
Table 10-16 shows the mapping of RWD bytes to byte lanes of the AHB read and write data buses.
10.4.7
Read/Write Access Address Register (RWA)
The read/write access address register, shown in
, provides the system bus address to be
accessed when initiating a read or a write access.
Table 10-16. RWD byte lane data placement
Transfer Size
and byte offset
RWA(2:0)
RWD
31–24
23–16
15–8
7–0
Byte @000
0 0 0
—
—
—
AHB[7
–
0]
Byte @001
0 0 1
—
—
—
AHB[15
–
8]
Byte @010
0 1 0
—
—
—
AHB[23
–
16]
Byte @011
0 1 1
—
—
—
AHB[31
–
24]
Byte @100
1 0 0
—
—
—
AHB[39
–
32]
Byte @101
1 0 1
—
—
—
AHB[47
–
40]
Byte @110
1 1 0
—
—
—
AHB[55
–
48]
Byte @111
1 1 1
—
—
—
AHB[63
–
56]
Half @000
0 0 0
—
—
AHB[15
–
8]
AHB[7
–
0]
Half @010
0 1 0
—
—
AHB[31
–
24]
AHB[23
–
16]
Half @100
1 0 0
—
—
AHB[47
–
40]
AHB[39
–
32]
Half @110
1 1 0
—
—
AHB[63
–
56]
AHB[55
–
48]
Word @000
0 0 0
AHB[31
–
24]
AHB[23
–
16]
AHB[15
–
8]
AHB[7
–
0]
Word @100
1 0 0
AHB[63
–
56]
AHB[55
–
48]
AHB[47
–
40]
AHB[39
–
32]
Doubleword @000
0 0 0
—
—
—
—
First RWD pass
AHB[31
–
24]
AHB[23
–
16]
AHB[15
–
8]
AHB[7
–
0]
Second RWD pass
AHB[63
–
56]
AHB[55
–
48]
AHB[47
–
40]
AHB[39
–
32]
Note:
“—” indicates byte lanes which will contain unused data.
31
0
Field
Read/Write Data
Reset
All zeros
R/W
Read/Write
Number
0xA
Figure 10-10. Read/Write Access Address Register (RWA)