MC68HC812A4 Datasheet, PDF (97/342 Pages) Motorola, Inc – 16-bit device composed of standard on-chip peripheral modules connected by an intermodule bus. Modules include

Bus Control and Input/Output (I/O)
Registers
6.4.3 Port B Data Register
Address: $0001
Bit 7
6
5
4
3
2
Read:
PB7
PB6
PB5
PB4
PB3
PB2
Write:
Reset: 0
0
0
0
0
0
Expanded and peripheral: ADDR7 ADDR6 ADDR5 ADDR4 ADDR3 ADDR2
Figure 6-3. Port B Data Register (PORTB)
1
PB1
0
ADDR1
Bit 0
PB0
0
ADDR0
Read: Anytime, if register is in the map
Write: Anytime, if register is in the map
Bits PB7–PB0 correspond to address lines ADDR7–ADDR0. When this
port is not used for external addresses such as in single-chip mode,
these pins can be used as general-purpose I/O. DDRB determines the
primary direction of each pin. This register is not in the on-chip map in
expanded and peripheral modes.
6.4.4 Port B Data Direction Register
Advance Information
MOTOROLA
Address: $0003
Bit 7
6
5
4
3
2
1
Read:
DDRB7 DDRB6 DDRB5 DDRB4 DDRB3 DDRB2 DDRB1
Write:
Reset: 0
0
0
0
0
0
0
Figure 6-4. Port B Data Direction Register (DDRB)
Bit 0
DDRB0
0
Read: Anytime, if register is in the map
Write: Anytime, if register is in the map
This register determines the primary direction for each port B pin when
functioning as a general-purpose I/O port. DDRB is not in the on-chip
map in expanded and peripheral modes.
1 = Associated pin is an output.
0 = Associated pin is a high-impedance input.
Bus Control and Input/Output (I/O)
MC68HC812A4 — Rev. 3.0
97