mc9s12e256 Freescale Semiconductor, Inc, mc9s12e256 Datasheet - Page 526

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

Chapter 18 Multiplexed External Bus Interface (MEBIV3)
a
b
526
MODC
No writes to the MOD bits are allowed while operating in a secure mode. For more details, refer to
Device Overview
If you are in a special single-chip or special test mode and you write to this register, changing to normal single-chip mode, then
one allowed write to this register remains. If you write to normal expanded or emulation mode, then no writes remain.
Field
EMK
EME
IVIS
0
0
0
0
1
1
1
1
3
1
0
MODB
Internal Visibility (for both read and write accesses) — This bit determines whether internal accesses
generate a bus cycle that is visible on the external bus.
Normal: write once
Emulation: write never
Special: write anytime
0 No visibility of internal bus operations on external bus.
1 Internal bus operations are visible on external bus.
Emulate Port K
Normal: write once
Emulation: write never
Special: write anytime
0 PORTK and DDRK are in the memory map so port K can be used for general-purpose I/O.
1 If in any expanded mode, PORTK and DDRK are removed from the memory map.
In single-chip modes, PORTK and DDRK are always in the map regardless of the state of this bit.
In special peripheral mode, PORTK and DDRK are never in the map regardless of the state of this bit.
Emulate Port E
Normal and Emulation: write never
Special: write anytime
0 PORTE and DDRE are in the memory map so port E can be used for general-purpose I/O.
1 If in any expanded mode or special peripheral mode, PORTE and DDRE are removed from the memory map.
In single-chip modes, PORTE and DDRE are always in the map regardless of the state of this bit.
0
0
1
1
0
0
1
1
Removing the registers from the map allows the user to emulate the function of these registers externally.
(MC9S12E256DGV1)”.
MODA
0
1
0
1
0
1
0
1
Table 18-8. MODC, MODB, and MODA Write Capability
Table 18-7. MODE Field Descriptions (continued)
Normal expanded narrow
Normal expanded wide
Special single chip
Normal single chip
MC9S12E256 Data Sheet, Rev. 1.08
Special peripheral
Emulation narrow
Emulation wide
Special test
Mode
Description
MODB and MODA write once
write anytime but not to 110
write anytime but not to 110
MODC, MODB, and MODA
MODC, MODB, and MODA
MODx Write Capability
MODC write never,
but not to 110
a
No write
No write
No write
No write
No write
Chapter 1, “MC9S12E256
Freescale Semiconductor
b
2