mc9s12e256 Freescale Semiconductor, Inc, mc9s12e256 Datasheet - Page 525

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

18.3.2.9
Read: Anytime (provided this register is in the map).
Write: Each bit has specific write conditions. Please refer to the descriptions of each bit on the following
pages.
The MODE register is used to establish the operating mode and other miscellaneous functions (i.e.,
internal visibility and emulation of port E and K).
In special peripheral mode, this register is not accessible but it is reset as shown to system configuration
features. Changes to bits in the MODE register are delayed one cycle after the write.
This register is not in the on-chip memory map in expanded and special peripheral modes. Therefore, these
accesses will be echoed externally.
Freescale Semiconductor
Normal Expanded Wide
MOD[C:A]
Emulation Expanded
Emulation Expanded
Field
Special Single Chip
Normal Single Chip
7:5
Normal Expanded
Special Test
Peripheral
Mode Select Bits — These bits indicate the current operating mode.
If MODA = 1, then MODC, MODB, and MODA are write never.
If MODC = MODA = 0, then MODC, MODB, and MODA are writable with the exception that you cannot change
to or from special peripheral mode
If MODC = 1, MODB = 0, and MODA = 0, then MODC is write never. MODB and MODA are write once, except
that you cannot change to special peripheral mode. From normal single-chip, only normal expanded narrow and
normal expanded wide modes are available.
See
Mode Register (MODE)
Narrow
Narrow
Reset
Wide
Table 18-8
W
R
MODC
and
0
0
0
0
1
1
1
1
7
Table
= Unimplemented or Reserved
MODB
18-16.
Figure 18-14. Mode Register (MODE)
Table 18-7. MODE Field Descriptions
0
0
1
1
0
0
1
1
6
MC9S12E256 Data Sheet, Rev. 1.08
MODA
0
1
0
1
0
1
0
1
5
Description
4
0
0
0
0
0
0
0
0
0
Chapter 18 Multiplexed External Bus Interface (MEBIV3)
IVIS
0
1
1
1
0
0
0
0
3
0
0
0
0
0
0
0
0
0
2
EMK
0
1
0
1
0
0
0
0
1
EME
0
1
0
1
0
0
0
0
0
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