DDR memory controller (MPMC)
RM0082
116/844
Doc ID 018672 Rev 1
AHB-memory controller transaction mapping equations
For AHB ports, a WORD is defined as 32 bits (4 bytes) and is the maximum size supported
for a 32 bit AHB port.
shows examples of the mapping of various AHB transaction
bursts and sizes to the corresponding Memory Controller core transaction lengths for a 32
bit wide AHB port interface.
BYTE
0x6
0x--Aa------------
BYTE
0x7
0xAa--------------
HALF WORD
0x0
0x------------BbAa
HALF WORD
0x2
0x--------BbAa----
HALF WORD
0x4
0x----BbAa--------
HALF WORD
0x6
0xBbAa------------
WORD
0x0
0x--------DdCcBbAa
WORD
0x4
0xDdCcBbAa--------
Table 57.
READ/WRITE data alignment - Big Endian
Transaction type
Address
Data alignment - big endian
BYTE
0x0
0xAa--------------
BYTE
0x1
0x--Aa------------
BYTE
0x2
0x----Aa----------
BYTE
0x3
0x------Aa--------
BYTE
0x4
0x--------Aa------
BYTE
0x5
0x----------Aa----
BYTE
0x6
0x------------Aa--
BYTE
0x7
0x--------------Aa
HALF WORD
0x0
0xAaBb------------
HALF WORD
0x2
0x----AaBb--------
HALF WORD
0x4
0x--------AaBb----
HALF WORD
0x6
0x------------AaBb
WORD
0x0
0xAaBbCcDd--------
WORD
0x4
0x--------AaBbCcDd
Table 56.
READ/WRITE data alignment - Little Endian (continued)
Transaction type
Address
Data alignment - little endian