Chapter 3 Memory Mapping Control (S12XMMCV4)
MC9S12XE-Family Reference Manual , Rev. 1.21
194
Freescale Semiconductor
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indicated here currently are not available from Freescale for import or sale in the United States prior to September 2010
Table 3-7 shows the address boundaries of each chip select and the relationship with the implemented
resources (internal) parameters.
Table 3-6. MMCCTL0 Field Descriptions
Field
Description
7–6
CS3E[1:0]
Chip Select 3 Enables — These bits enable the external chip select CS3 output which is asserted during
accesses to specic external addresses. The associated global address range is shown in
Table 3-7 and
Chip select 3 is only active if enabled in Normal Expanded mode, Emulation Expanded mode.
The function disabled in all other operating modes.
00
Chip select 3 is disabled
01,10,11 Chip select 3 is enabled
5–4
CS2E[1:0]
Chip Select 2 Enables — These bits enable the external chip select CS2 output which is asserted during
accesses to specic external addresses. The associated global address range is shown in
Table 3-7 and
Chip select 2 is only active if enabled in Normal Expanded mode, Emulation Expanded mode.
The function disabled in all other operating modes.
00
Chip select 2 is disabled
01,10,11 Chip select 2 is enabled
3–2
CS1E[1:0]
Chip Select 1 Enables — These bits enable the external chip select CS1 output which is asserted during
accesses to specic external addresses. The associated global address range is shown in
Table 3-7 and
Chip select 1 is only active if enabled in Normal Expanded mode, Emulation Expanded mode.
The function disabled in all other operating modes.
00
Chip select 1 is disabled
01,10,11 Chip select 1 is enabled
1–0
CS0E[1:0]
Chip Select 0 Enables — These bits enable the external chip select CS0 output which is asserted during
accesses to specic external addresses. The associated global address range is shown in
Table 3-7 and
Chip select 0 is only active if enabled in Normal Expanded mode, Emulation Expanded mode.
The function disabled in all other operating modes.
00
Chip select 0 is disabled
01,10,11 Chip select 0 is enabled
Table 3-7. Global Chip Selects Memory Space
Chip Selects
Bottom Address
Top Address
CS3
0x00_0800
0x0F_FFFF minus RAMSIZE(1)
1. External RPAGE accesses in (NX, EX)
CS2(2)
2. When ROMHM is set (see ROMHM in
Table 3-16) the CS2 is asserted in the space occupied by this on-
chip memory block.
0x14_0000
0x1F_FFFF
CS1
0x20_0000
0x3F_FFFF
CS0(3)
the CS0 is not asserted in the space occupied by this on-chip memory block.
0x40_0000
0x7F_FFFF minus FLASHSIZE(4)
4. External PPAGE accesses in (NX, EX)