Memory
MCF51CN128 Reference Manual, Rev. 6
4-2
Freescale Semiconductor
is the generic, high level, memory map applicable to the MCF51CN128 family. Devices
(including the MCF51CN128) which include off-chip expansion capability alias smaller memories across
the range shown as shown in
.
1
The figure shows that MCF51CN128 includes 128K bytes of flash memory. This memory is 32 times
beginning at 0x(00)00_0000, but is also aliased at 0x(00)02_0000, 0X(00)04_0000, 0x(00)06_0000 and
so on up through 0x(00)3D_0000.
The region from 0x(00)40_0000 through 0x(00)7F_FFFF can be used by the Mini-FlexBus for off-chip
expansion, allowing for natural code expansion from flash to off-chip memory if required.
The 2 MB region at 0x(00)80_0000 is allocated for on-chip RAM. Only 24 KB of that is physically
implemented on the MCF51CN128. RAM address decoding is aliased every 32 KB across the 2MB region
from 0x(00)80_0000 to 0x(00)9F_FFFF.
Regions within the memory map are subject to restrictions with regard to the types of CPU accesses
allowed. These are outlined in
. Non-supported access types terminate the bus cycle with an error
(and typically generate a system reset in response to the error termination).
1. This is not necessarily true of parts with no external expansion port.
128K bytes of physical flash
memory
0x(00)00_0000
0x(00)01_FFFF
flash memory alias 1
0x(00)02_0000
0x(00)03_FFFF
flash memory alias 2
0x(00)04_0000
0x(00)05_FFFF
0x(00)00_0000
Allocated to on-chip flash
memory
...
0x(00)06_0000
0x(00)3F_FFFF
0x(00)39_FFFF
flash memory alias 30
0x(00)3A_0000
0x(00)3C_FFFF
flash memory alias 31
0x(00)3D_0000
0x(00)3F_FFFF
Figure 4-2. Flash Memory Aliasing