MC68HC812A4 Datasheet, PDF (80/342 Pages) Motorola, Inc – 16-bit device composed of standard on-chip peripheral modules connected by an intermodule bus. Modules include

Operating Modes and Resource Mapping
5.3 Operating Modes
The states of the BKGD, MODB, and MODA pins during reset determine
the operating mode after reset.
The SMODN, MODB, and MODA bits in the MODE register show the
current operating mode and provide limited mode switching during
operation. The states of the BKGD, MODB, and MODA pins are latched
into these bits on the rising edge of the reset signal.
Table 5-1. Mode Selection
BKGD MODB MODA
Mode
Port A
Port B
Port C Port D
0
0
0
Special single-chip
G.P.⁽¹⁾ I/O ^{G.P. I/O G.P. I/O}
0
0
1 Special expanded narrow ADDR DATA G.P. I/O
0
1
0
Special peripheral
ADDR DATA DATA
0
1
1
Special expanded wide ADDR DATA DATA
1
0
0
Normal single chip
G.P. I/O G.P. I/O G.P. I/O
1
0
1 Normal expanded narrow ADDR DATA G.P. I/O
1
1
0
Reserved
(forced to peripheral)
—
—
—
1
1
1
Normal expanded wide ADDR DATA DATA
1. G.P. = General purpose
The two basic types of operating modes are:
• Normal modes — Some registers and bits are protected against
accidental changes.
• Special modes — Protected control registers and bits are allowed
greater access for special purposes such as testing and
emulation.
A system development and debug feature, background debug mode
(BDM), is available in all modes. In special single-chip mode, BDM is
active immediately after reset.
MC68HC812A4 — Rev. 3.0
80
Operating Modes and Resource Mapping
Advance Information
MOTOROLA