MPC563XM Reference Manual, Rev. 1
392
Freescale Semiconductor
Preliminary—Subject to Change Without Notice
The number of external transfers for each internal AHB master request is determined by the HSIZE value
for that request relative to the port size. For example, a half-word write to @011 (misaligned case #2) with
16-bit port size results in 4 external 16-bit transfers because the HSIZE is 64-bits. For cases where two or
more external transfers are required for one internal transfer request, these external accesses are considered
part of a "small access" set, as described in
Section 13.5.2.6, “Small Accesses (Small Port Size and Short
.
Since all transfers are aligned on the external bus, normal timing diagrams and protocol apply. Note that
the TSIZ[0:1] signals are not intended to be used for misaligned accesses, so they are not specified in
.
Table 13-24. Misalignment Cases Supported by a 64 bit AMBA EBI (external bus)
No.
1
PS
2
Program Size
and byte offset
ADDR[29:31]
3
WE_BE[0:3]
4
1
0
Half @0x1,0x9
000
1001
1
000
010
1011
0111
2
0
Half @0x3,0xB
000
100
1110
0111
1
010
100
1011
0111
3
0
Half @0x5,0xD
100
1001
1
100
110
1011
0111
4
0
Half @0x7,0xF
(2 AHB
transfers)
111
5
1110
-
000
0111
4
1
110
1011
-
000
0111
5
0
Word @0x1,0x9
000
100
1000
0111
1
000
010
100
1011
0011
0111
6
0
Word @0x2,0xA
000
100
1100
0011
1
010
100
0011
0011
7
0
Word @0x3,0xB
000
100
1110
0001
1
010
100
110
1011
0011
0111
8
0
Word @0x5,0xD
(2 AHB
transfers)
100
1000
-
000
0111
8
1
100
110
1011
0011
-
000
0111