MC908AP8CFBE Datasheet, PDF (261/324 Pages) Freescale Semiconductor, Inc – Microcontrollers

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.
$0000
$0001
$0002
$0003
$0004
$0005
$0006
$0007
$000C
Register Name
Read:
Port A
Data
Register
(PTA)
Write:
Reset:
Read:
Port B
Data
Register
(PTB)
Write:
Reset:
Read:
Port C Data Register (PTC) 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 C
(DDRC)
Write:
Reset:
Read:
Data Direction Register D
(DDRD)
Write:
Reset:
Port-A LED Control ^Read:
Register Write:
(LEDA) Reset:
Bit 7
PTA7
PTB7
PTC7
PTD7
DDRA7
0
DDRB7
0
DDRC7
0
DDRD7
0
LEDA7
0
6
PTA6
PTB6
PTC6
PTD6
DDRA6
0
DDRB6
0
DDRC6
0
DDRD6
0
LEDA6
0
5
PTA5
PTB5
PTC5
PTD5
DDRA5
0
DDRB5
0
DDRC5
0
DDRD5
0
LEDA5
0
4
3
PTA4
PTA3
Unaffected by reset
PTB4
PTB3
Unaffected by reset
PTC4
PTC3
Unaffected by reset
PTD4
PTD3
Unaffected by reset
DDRA4 DDRA3
0
0
DDRB4 DDRB3
0
0
DDRC4 DDRC3
0
0
DDRD4 DDRD3
0
0
LEDA4 LEDA3
0
0
Figure 16-1. I/O Port Register Summary
2
PTA2
PTB2
PTC2
PTD2
DDRA2
0
DDRB2
0
DDRC2
0
DDRD2
0
LEDA2
0
1
PTA1
PTB1
PTC1
PTD1
DDRA1
0
DDRB1
0
DDRC1
0
DDRD1
0
LEDA1
0
Bit 0
PTA0
PTB0
PTC0
PTD0
DDRA0
0
DDRB0
0
DDRC0
0
DDRD0
0
LEDA0
0
MC68HC908AP Family Data Sheet, Rev. 4
Freescale Semiconductor
259