External Bus Interface
MOTOROLA
MPC823e REFERENCE MANUAL
13-15
EXTERNAL BUS
13
INTERFACE
A typical single beat transfer assumes that the external memory has a 32-bit port size. The
MPC823e provides an effective mechanism for interfacing with 16-bit port size memories
and 8-bit port size memories, thus allowing transfers to these devices when they are
controlled by the internal memory controller. The port size (PS) timing shown in the following
figures is representative of the PS field, which is described in
Section 15.3.1.1 Base
Registers
.
Figure 13-9. Single Beat, 32-Bit Data, Write Cycle From a 16-Bit Port Size
CLKOUT
A[6:31]
TS
BR
BG
BB
DATA
TA
RD/WR
BURST
TSIZ[0:1]
PS
‘10’
‘00’
‘10’
A
A + 2
ABCDEFGH
EFGHEFGH
STS
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