MC908JL3ECPE Datasheet, PDF (103/180 Pages) Freescale Semiconductor, Inc – Microcontrollers

Chapter 10
Input/Output (I/O) Ports
10.1 Introduction
Twenty three (23) bidirectional input-output (I/O) pins form three 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.
20-pin devices have non-bonded pins. These pins should be configured
either as outputs driving low or high, or as inputs with internal pullups
enabled. Configuring these non-bonded pins in this manner will prrevent
any excess current compsumption caused by floating inputs.
Addr.
$0000
$0001
$0003
$0004
$0005
$0007
Register Name
Read:
Port A Data Register
(PTA)
Write:
Reset:
Read:
Port B Data Register
(PTB)
Write:
Reset:
Read:
Port D Data Register
(PTD)
Write:
Reset:
Read:
Data Direction Register A
(DDRA)
Write:
Reset:
Read:
Data Direction Register B
(DDRB)
Write:
Reset:
Read:
Data Direction Register D
(DDRD)
Write:
Reset:
Bit 7
0
PTB7
PTD7
0
0
DDRB7
0
DDRD7
0
6
PTA6
PTB6
PTD6
DDRA6
0
DDRB6
0
DDRD6
0
5
PTA5
PTB5
PTD5
DDRA5
0
DDRB5
0
DDRD5
0
4
3
PTA4
PTA3
Unaffected by reset
PTB4
PTB3
Unaffected by reset
PTD4
PTD3
Unaffected by reset
DDRA4 DDRA3
0
0
DDRB4 DDRB3
0
0
DDRD4 DDRD3
0
0
2
PTA2
PTB2
PTD2
DDRA2
0
DDRB2
0
DDRD2
0
1
PTA1
PTB1
PTD1
DDRA1
0
DDRB1
0
DDRD1
0
Bit 0
PTA0
PTB0
PTD0
DDRA0
0
DDRB0
0
DDRD0
0
Figure 10-1. I/O Port Register Summary
MC68HC908JL3E Family Data Sheet, Rev. 4
Freescale Semiconductor
103