mc68hc908gr8a Freescale Semiconductor, Inc, mc68hc908gr8a Datasheet - Page 115

• Manufacturer Part Number: mc68hc908gr8a
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Chapter 12
Input/Output (I/O) Ports
12.1 Introduction
Bidirectional input-output (I/O) pins form five parallel ports. All I/O pins are programmable as inputs or
outputs. All individual bits within port A, port C, and port D are software configurable with pullup devices
if configured as input port bits. The pullup devices are automatically and dynamically disabled when a port
bit is switched to output mode.
Freescale Semiconductor
Addr.
$0000
$0001
$0002
$0003
$0004
Data Direction Register A
Register Name
Port A Data Register
Port B Data Register
Port C Data Register
Port D Data Register
Connect any unused I/O pins to an appropriate logic level, either V
V
termination reduces excess current consumption and the possibility of
electrostatic damage.
Not all port pins are bonded out in all packages. Care sure be taken to make
any unbonded port pins an output to prevent them from being floating
inputs.
SS
See page 117.
See page 120.
See page 122.
See page 124.
See page 118.
. Although the I/O ports do not require termination for proper operation,
(DDRA)
(PTC)
(PTD)
(PTA)
(PTB)
MC68HC908GR8A • MC68HC908GR4A Data Sheet, Rev. 5
Reset:
Reset:
Reset:
Reset:
Reset:
Read:
Read:
Read:
Read:
Read:
Write:
Write:
Write:
Write:
Write:
Figure 12-1. I/O Port Register Summary
Bit 7
0
0
0
0
0
0
= Unimplemented
PTD6
6
0
0
0
0
0
NOTE
PTD5
PTB5
5
0
0
0
0
Unaffected by reset
Unaffected by reset
Unaffected by reset
Unaffected by reset
PTB4
PTD4
4
0
0
0
0
DDRA3
PTA3
PTB3
PTD3
3
0
0
DDRA2
PTA2
PTB2
PTD2
2
0
0
DD
or
DDRA1
PTA1
PTB1
PTC1
PTD1
1
0
DDRA0
PTA0
PTB0
PTC0
PTD0
Bit 0
0
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