S912XEG384J3VA Datasheet, PDF (214/1324 Pages) Freescale Semiconductor, Inc – MC9S12XEP100 Reference Manual Covers MC9S12XE Family

Chapter 3 Memory Mapping Control (S12XMMCV4)
3.4.2.5 Memory Configuration
Two bits in the MMCCTL1 register (ROMHM, RAMHM) configure the mapping of the local address
(0x4000-0x7FFF) in the global memory map.
ROMHM, RAMHM are write once in normal and emulation modes and anytime in special modes.
Three areas are identified (See Figure 3-21):
• Program FLASH (0x7F_4000-0x7F_7FFF) when ROMHM = 0.
• External Space (0x14_4000-0x14_7FFF) when ROMHM = 1 and RAMHM = 0.
• XSRAM Space (0x0F_C000-0x0F_FFFF) when ROMHM = 1 and RAMHM = 1.
Table 3-19 shows the translation from the local memory map to the global memory map taking in
consideration the different configurations of ROMHM and RAMHM.
Table 3-19. ROMHM and RAMHM Address Location
Local Address
0x4000 - 0x7FFF
0x2000 - 0x3FFF
0x2000 - 0x3FFF
ROMHM RAMHM
Global Address
0
X
0x7F_4000 - 0x7F_7FFF
1
0
0x14_4000 - 0x14_7FFF
0x0F_C000 - 0x0F_FFFF
1
1
0x0F_A000 - 0x0F_BFFF
1
0
0x0F_E000 - 0x0F_FFFF
Location
Internal Flash
External Space
Bottom of the Implemented RAM
Fixed up to 8K RAM
Fixed up to 8K RAM
Table 3-20 describes the application note of the RAM configuration and its dedicated global address.
Table 3-20. RAM Configuration
phase
After reset
During setup
Normal Operation
RPAGE
ROMHM
RPAGE = 0xFD
0
(Reset value)
RPAGE = 0xFD
1
(Reset value)
(0x00 <= RPAGE <= 0xF9)
1
(0xFA <= RPAGE <= 0xFF)
1
RAMHM
0
1
1
1
RAM AREA
12 Kilobytes
Global Address
0x0F_D000 - 0x0F_FFFF
24 Kilobytes 0x0F_A000 - 0x0F_FFFF
28 Kilobytes 0x00_0000 - 0x0F_9FFF
24 Kilobytes 0x0F_A000 - 0x0F_FFFF
MC9S12XE-Family Reference Manual Rev. 1.25
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