mc68hc11d0cfn2 Freescale Semiconductor, Inc, mc68hc11d0cfn2 Datasheet - Page 69

• Manufacturer Part Number: mc68hc11d0cfn2
• Description: M68hc11 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

5.3 Port B
5.3.1 Port B Data Register
5.3.2 Port B Data Direction Register
MC68HC711D3 — Rev. 2
MOTOROLA
Port B is an 8-bit, general-purpose I/O port with a data register (PORTB) and a data
direction register (DDRB).
PORTB can be read at any time. Inputs return the sensed levels at the pin, while
outputs return the input level of the port B pin drivers. If PORTB is written, the data
is stored in an internal latch and can be driven only if port B is configured for
general-purpose outputs in single-chip or bootstrap mode.
Port B pins are general--purpose inputs out of reset in single-chip and bootstrap
modes. These pins are outputs (the high-order address bits) out of reset in
expanded multiplexed and test modes.
DDB7–DDB0 — Data Direction Bits for Port B
Alt. Func.:
Address:
Address:
•
•
Reset:
Reset:
Read:
Write:
Read:
Write:
1 = Corresponding port B pin configured as output
0 = Corresponding port B pin configured for input only
Freescale Semiconductor, Inc.
In the single-chip mode, port B pins are general-purpose I/O pins
(PB7–PB0).
In the expanded-multiplexed mode, all of the port B pins act as the
high-order address bits (A15–A8) of the address bus.
For More Information On This Product,
$0006
DDB7
$0004
Bit 7
Bit 7
PB7
A15
Figure 5-3. Data Direction Register for Port B (DDRB)
0
0
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Figure 5-2. Port B Data Register (PORTB)
Input/Output (I/O) Ports
DDB6
PB6
A14
6
0
6
0
DDB5
PB5
A13
5
0
5
0
DDB4
PB4
A12
4
0
4
0
DDB3
PB3
A11
3
0
3
0
DDB2
PB2
A10
2
0
2
0
Input/Output (I/O) Ports
DDB1
PB1
A9
1
0
1
0
Data Sheet
DDB0
Bit 0
Bit 0
PB0
A8
0
0
Port B
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