Architecture Block Diagram
Table 1-2 Bus Signal Names
Name
Function
Program Memory Interface
pdb_m[15:0]
cdbw[15:0]
Program data bus for instruction word fetches or read operations.
Primary core data bus used for program memory writes. (Only these 16 bits of the cdbw[31:0] bus
are used for writes to program memory.)
pab[20:0]
Program memory address bus. Data is returned on pdb_m bus.
Primary Data Memory Interface Bus
cdbr_m[31:0] Primary core data bus for memory reads. Addressed via xab1 bus.
cdbw[31:0]
xab1[23:0]
Primary core data bus for memory writes. Addressed via xab1 bus.
Primary data address bus. Capable of addressing bytes1, words, and long data types. Data is written
on cdbw and returned on cdbr_m. Also used to access memory-mapped I/O.
Secondary Data Memory Interface
xdb2_m[15:0] Secondary data bus used for secondary data address bus xab2 in the dual memory reads.
xab2[23:0]
Secondary data address bus used for the second of two simultaneous accesses. Capable of
addressing only words. Data is returned on xdb2_m.
Peripheral Interface Bus
IPBus [15:0]
Peripheral bus accesses all on-chip peripherals registers. This bus operates at the same clock rate
as the Primary Data Memory and therefore generates no delays when accessing the processor.
Write data is obtained from cdbw. Read data is provided to cdbr_m.
1. Byte accesses can only occur in the bottom half of the memory address space. The MSB of the address will be forced
to 0.
56F8345 Technical Data, Rev. 17
Freescale Semiconductor
Preliminary
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FREESCALE [ Freescale ]
