MC912DG128A Motorola, MC912DG128A Datasheet - Page 65

• Manufacturer Part Number: MC912DG128A
• Description: Microcontrollers
• Manufacturer: Motorola

Special Operating
Modes
MODE — Mode Register
3-modes
MOTOROLA
RESET:
RESET:
RESET:
SMODN
Bit 7
0
0
0
MODB
6
0
0
1
There are three special operating modes that correspond to normal
operating modes. These operating modes are commonly used in factory
testing and system development. In addition, there is a special
peripheral mode, in which an external master, such as an I.C. tester, can
control the on-chip peripherals.
MODA
Special Single-Chip Mode — This mode can be used to force the
MCU to active BDM mode to allow system debug through the
BKGD pin. There are no external address and data buses in this
mode. The MCU operates as a stand-alone device and all
program and data space are on-chip. External port pins can be
used for general-purpose I/O.
Special Expanded Wide Mode — This mode can be used for
emulation of normal expanded wide mode and emulation of
normal single-chip mode. Ports A and B are used for the 16-bit
multiplexed address/data bus.
Special Expanded Narrow Mode — This mode can be used for
emulation of normal expanded narrow mode. Ports A and B are
used for the16-bit address bus. Port A is used as the data bus,
multiplexed with addresses. In this mode, 16-bit data is presented
one byte at a time, the high byte followed by the low byte. The
address is automatically incremented on the second cycle.
Special Peripheral Mode — The CPU is not active in this mode.
An external master can control on-chip peripherals for testing
purposes. It is not possible to change to or from this mode without
going through reset. Background debugging should not be used
while the MCU is in special peripheral mode as internal bus
conflicts between BDM and the external master can cause
improper operation of both functions.
5
0
1
0
ESTR
4
1
1
1
Operating Modes
IVIS
3
1
1
1
EBSWAI
2
0
0
0
EMK
1
1
1
1
MC68HC912DT128A Rev 2.0
EME
Bit 0
1
1
1
Special Single Chip
Operating Modes
Operating Modes
Special Exp Nar
Peripheral
$000B
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