mc9s12e256 Freescale Semiconductor, Inc, mc9s12e256 Datasheet - Page 554

• Manufacturer Part Number: mc9s12e256
• Description: Hcs12 Microcontrollers 16-bit Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Chapter 19 Module Mapping Control (MMCV4)
In emulation modes, if the EMK bit in the MODE register (see
Interface
memory map and become external accesses.
19.4.2.2
When the EMK bit in the MODE register (see
(MEBIV3)”) is set, port K bit 7 is used as an active-low emulation chip select signal, ECS. This signal is
active when the system is in emulation mode, the EMK bit is set and the FLASH or ROM space is being
addressed subject to the conditions outlined in
Signal
19.4.2.3
When the EMK bit in the MODE register (see
(MEBIV3)”) is set, port K bit 6 is used as an active-low external chip select signal, XCS. This signal is
active only when the ECS signal described above is not active and when the system is addressing the
external address space. Accesses to 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
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
for easy reference).
Based upon the system configuration, the program page window will consider its access to be either
internal or external as defined in
554
Functionality.” When the EMK bit is clear, this pin is used for general purpose I/O.
(MEBIV3)”) is set, the data and data direction registers for port K are removed from the on-chip
Memory Expansion
Emulation Chip Select Signal
External Chip Select Signal
pag_sw1:pag_sw0
00
01
10
11
Table 19-16. Allocated Off-Chip Memory Options
Table
MC9S12E256 Data Sheet, Rev. 1.08
19-17.
Table 19-16
Section 19.4.3.2, “Extended Address (XAB19:14) and ECS
Off-Chip Space
Chapter 18, “Multiplexed External Bus Interface
Chapter 18, “Multiplexed External Bus Interface
876K bytes
768K bytes
512K bytes
0K byte
(this table matches
Chapter 18, “Multiplexed External Bus
Table 19-12
On-Chip Space
128K bytes
256K bytes
512K bytes
1M byte
Freescale Semiconductor
but is repeated here