MC68HC908LD64 Datasheet, PDF (294/362 Pages) Freescale Semiconductor, Inc – Microcontrollers

Input/Output (I/O) Ports
19.2 Introduction
Thirty-nine (39) bidirectional input-output (I/O) pins form five 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
6
5
4
3
$0000
Read:
Port A Data Register
(PTA)
Write:
Reset:
PTA7
PTA6
PTA5 PTA4 PTA3
Unaffected by reset
$0001
Read:
Port B Data Register
(PTB)
Write:
Reset:
PTB7
PTB6
PTB5 PTB4 PTB3
Unaffected by reset
$0002
Read: 0
Port C Data Register
(PTC)
Write:
Reset:
PTC6 PTC5 PTC4 PTC3
Unaffected by reset
$0003
Read:
Port D Data Register
(PTD)
Write:
Reset:
PTD7
PTD6
PTD5 PTD4 PTD3
Unaffected by reset
$0004
Read:
Data Direction Register A
(DDRA)
Write:
Reset:
DDRA7
0
DDRA6
0
DDRA5
0
DDRA4
0
DDRA3
0
$0005
Read:
Data Direction Register B
(DDRB)
Write:
Reset:
DDRB7
0
DDRB6
0
DDRB5
0
DDRB4
0
DDRB3
0
= Unimplemented
Figure 19-1. Port I/O Register Summary
2
PTA2
PTB2
PTC2
PTD2
DDRA2
0
DDRB2
0
1
PTA1
PTB1
PTC1
PTD1
DDRA1
0
DDRB1
0
Bit 0
PTA0
PTB0
PTC0
PTD0
DDRA0
0
DDRB0
0
Data Sheet
294
Input/Output (I/O) Ports
MC68HC908LD64 — Rev. 3.0
Freescale Semiconductor