Freescale Semiconductor, Inc.
Parallel Input/Output
Port B
7.4.2 Da ta Dire c tion Re g iste r B (DDRB)
The contents of the port B data direction register (DDRB) determine
whether each port B pin is an input or an output. Writing a logic one to a
DDRB bit enables the output buffer for the associated port B pin. A
DDRB bit set to a logic one also disables the pulldown device for that pin.
Writing a logic zero to a DDRB bit disables the output buffer for the
associated port B pin. A reset initializes all DDRB bits to logic zeros,
configuring all port B pins as inputs.
$0005
Read:
Write:
Reset:
Bit 7
6
5
4
3
2
1
Bit 0
DDRB7 DDRB6 DDRB5 DDRB4 DDRB3 DDRB2 DDRB1 DDRB0
0
0
0
0
0
0
0
0
Figure 7-6. Data Direction Register B (DDRB)
DDRB7–DDRB0 — Port B Data Direction Bits
These read/write bits control port B data direction. Reset clears the
bits DDRB7–DDRB0.
1 = Corresponding port B pin configured as output and pulldown
device disabled
0 = Corresponding port B pin configured as input
MC68HC705JJ7/MC68HC705JP7 — Rev. 3.0
General Release Specification
Parallel Input/Output
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