MC9S12KG128_10 Datasheet, PDF (560/606 Pages) Freescale Semiconductor, Inc – HCS12 Microcontrollers

Chapter 19 Module Mapping Control (MMCV4) Block Description
unimplemented locations within the register space or to locations that are removed from the map (i.e., ports
A and B in expanded modes) will not cause this signal to become active. When the EMK bit is clear, this
pin is used for general purpose I/O.
19.4.3 Memory Expansion
The HCS12 core architecture limits the physical address space available to 64K bytes. The program page
index register allows for integrating up to 1M byte of FLASH or ROM into the system by using the six
page index bits to page 16K byte blocks into the program page window located from 0x8000 to 0xBFFF
in the physical memory space. The paged memory space can consist of solely on-chip memory or a
combination of on-chip and off-chip memory. This partitioning is configured at system integration through
the use of the paging configuration switches (pag_sw1:pag_sw0) at the core boundary. The options
available to the integrator are as given in Table 19-16 (this table matches Table 19-12 but is repeated here
for easy reference).
Table 19-16. Allocated Off-Chip Memory Options
pag_sw1:pag_sw0
00
01
10
11
Off-Chip Space
876K bytes
768K bytes
512K bytes
0K byte
On-Chip Space
128K bytes
256K bytes
512K bytes
1M byte
Based upon the system configuration, the program page window will consider its access to be either
internal or external as defined in Table 19-17.
Table 19-17. External/Internal Page Window Access
pag_sw1:pag_sw0
00
01
10
11
Partitioning
876K off-Chip,
128K on-Chip
768K off-chip,
256K on-chip
512K off-chip,
512K on-chip
0K off-chip,
1M on-chip
PIX5:0 Value
0x0000–0x0037
0x0038–0x003F
0x0000–0x002F
0x0030–0x003F
0x0000–0x001F
0x0020–0x003F
N/A
0x0000–0x003F
Page Window
Access
External
Internal
External
Internal
External
Internal
External
Internal
NOTE
The partitioning as defined in Table 19-17 applies only to the allocated
memory space and the actual on-chip memory sizes implemented in the
system may differ. Please refer to the device overview chapter for actual
sizes.
MC9S12KG128 Data Sheet, Rev. 1.16
560
Freescale Semiconductor