Datasheet

Input/Output (I/O) Ports
Data Sheet MC68HC908LJ24/LK24 — Rev. 2.1
376 Input/Output (I/O) Ports Freescale Semiconductor
18.2 Introduction
Forty-eight (48) bidirectional input-output (I/O) pins form six 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 7654321Bit 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
Figure 18-1. I/O Port Register Summary