Datasheet

MC68HC908AP Family Data Sheet, Rev. 4
Freescale Semiconductor 259
Chapter 16
Input/Output (I/O) Ports
16.1 Introduction
Thirty-two (32) bidirectional input-output (I/O) pins form four parallel ports. All I/O pins are programmable
as inputs or outputs.
NOTE
Connect any unused I/O pins to an appropriate logic level, either V
DD
or V
SS
.
Although the I/O ports do not require termination for proper operation,
termination reduces excess current consumption and the possibility of
electrostatic damage.
Addr. Register Name Bit 7 654321Bit 0
$0000
Port A Data Register
(PTA)
Read:
PTA7 PTA6 PTA5 PTA4 PTA3 PTA2 PTA1 PTA0
Write:
Reset: Unaffected by reset
$0001
Port B Data Register
(PTB)
Read:
PTB7 PTB6 PTB5 PTB4 PTB3 PTB2 PTB1 PTB0
Write:
Reset: Unaffected by reset
$0002 Port C Data Register (PTC)
Read:
PTC7 PTC6 PTC5 PTC4 PTC3 PTC2 PTC1 PTC0
Write:
Reset: Unaffected by reset
$0003 Port D Data Register (PTD)
Read:
PTD7 PTD6 PTD5 PTD4 PTD3 PTD2 PTD1 PTD0
Write:
Reset: Unaffected by reset
$0004
Data Direction Register A
(DDRA)
Read:
DDRA7 DDRA6 DDRA5 DDRA4 DDRA3 DDRA2 DDRA1 DDRA0
Write:
Reset: 00000000
$0005
Data Direction Register B
(DDRB)
Read:
DDRB7 DDRB6 DDRB5 DDRB4 DDRB3 DDRB2 DDRB1 DDRB0
Write:
Reset: 00000000
$0006
Data Direction Register C
(DDRC)
Read:
DDRC7 DDRC6 DDRC5 DDRC4 DDRC3 DDRC2 DDRC1 DDRC0
Write:
Reset: 00000000
$0007
Data Direction Register D
(DDRD)
Read:
DDRD7 DDRD6 DDRD5 DDRD4 DDRD3 DDRD2 DDRD1 DDRD0
Write:
Reset: 00000000
$000C
Port-A LED Control
Register
(LEDA)
Read:
LEDA7 LEDA6 LEDA5 LEDA4 LEDA3 LEDA2 LEDA1 LEDA0
Write:
Reset: 00000000
Figure 16-1. I/O Port Register Summary