Datasheet

MC68HC908QY4•MC68HC908QT4•MC68HC908QY2•MC68HC908QT2•MC68HC908QY1•MC68HC908QT1
162 Input/Output (I/O) Ports MOTOROLA
Input/Output (I/O) Ports
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12.3 Port A
Port A is an 6-bit special function port that shares all six of its pins with
the keyboard interrupt (KBI) module (see Section 14. Keyboard
Interrupt Module (KBI)). Each port A pin also has a software
configurable pullup device if the corresponding port pin is configured as
an input port.
NOTE: PTA2 is input only.
When the IRQ function is enabled in the configuration register 2
(CONFIG2), bit 2 of the port A data register (PTA) will always read a
logic 0. In this case, the BIH and BIL instructions can be used to read the
Addr.Register Name Bit 7654321Bit 0
$0000
Port A Data Register
(PTA)
See page 163.
Read: 0 AWUL
PTA5 PTA4 PTA3
PTA2
PTA1 PTA0
Write:
Reset: Unaffected by reset
$0001
Port B Data Register
(PTB)
See page 167.
Read:
PTB7 PTB6 PTB5 PTB4 PTB3 PTB2 PTB1 PTB0
Write:
Reset: Unaffected by reset
$0004
Data Direction Register A
(DDRA)
See page 164.
Read: 0 0
DDRA5 DDRA4 DDRA3
0
DDRA1 DDRA0
Write:
Reset:00000000
$0005
Data Direction Register B
(DDRB)
See page 168.
Read:
DDRB7 DDRB6 DDRB5 DDRB4 DDRB3 DDRB2 DDRB1 DDRB0
Write:
Reset:00000000
$000B
Port A Input Pullup
Enable Register
(PTAPUE)
See page 166.
Read:
OSC2EN
PTAPUE5 PTAPUE4 PTAPUE3 PTAPUE2 PTAPUE1 PTAPUE0
Write:
Reset:00000000
$000C
Port B Input Pullup
Enable Register
(PTBPUE)
See page 169.
Read:
PTBPUE7 PTBPUE6 PTBPUE5 PTBPUE4 PTBPUE3 PTBPUE2 PTBPUE1 PTBPUE0
Write:
Reset:00000000
= Unimplemented
Figure 12-1. I/O Port Register Summary