MC908GR16ACFA FREESCALE [Freescale Semiconductor, Inc], MC908GR16ACFA Datasheet - Page 115

• Manufacturer Part Number: MC908GR16ACFA
• Description: M68HC08 Microcontrollers
• Manufacturer: FREESCALE [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 118.
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)
Reset:
Reset:
Reset:
Reset:
Reset:
Read:
Read:
Read:
Read:
Read:
Write:
Write:
Write:
Write:
Write:
Figure 12-1. I/O Port Register Summary
DDRA7
MC68HC908GR16A Data Sheet, Rev. 1.0
PTD7
PTA7
PTB7
Bit 7
1
0
= Unimplemented
DDRA6
PTC6
PTD6
PTA6
PTB6
6
0
NOTE
DDRA5
PTC5
PTD5
PTA5
PTB5
5
0
DDRA4
Unaffected by reset
Unaffected by reset
Unaffected by reset
Unaffected by reset
PTA4
PTB4
PTC4
PTD4
4
0
DDRA3
PTA3
PTB3
PTC3
PTD3
3
0
DDRA2
PTA2
PTB2
PTC2
PTD2
2
0
DD
or
DDRA1
PTA1
PTB1
PTC1
PTD1
1
0
DDRA0
PTA0
PTB0
PTC0
PTD0
Bit 0
0
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