MC68HC08AZ32A Datasheet, PDF (155/312 Pages) Motorola, Inc – HCMOS Microcontroller Unit

13.2 Port A
Port A is an 8-bit general-purpose bidirectional I/O port.
Port A
13.2.1 Port A Data Register (PTA)
The port A data register contains a data latch for each of the eight port A pins.
Address: $0000
Bit 7
Read:
PTA7
Write:
Reset:
6
PTA6
5
PTA5
4
3
PTA4
PTA3
Unaffected by reset
2
PTA2
1
PTA1
Bit 0
PTA0
Figure 13-2. Port A Data Register (PTA)
PTA[7:0] — Port A Data Bits
These read/write bits are software programmable. Data direction of each port A pin is under the control
of the corresponding bit in data direction register A. Reset has no effect on port A data.
13.2.2 Data Direction Register A (DDRA)
Data direction register A determines whether each port A pin is an input or an output. Writing a 1 to a
DDRA bit enables the output buffer for the corresponding port A pin; a 0 disables the output buffer.
Address: $0004
Bit 7
Read:
DDRA7
Write:
Reset: 0
6
DDRA6
0
5
DDRA5
0
4
DDRA4
0
3
DDRA3
0
2
DDRA2
0
1
DDRA1
0
Bit 0
DDRA0
0
Figure 13-3. Data Direction Register A (DDRA)
DDRA[7:0] — Data Direction Register A Bits
These read/write bits control port A data direction. Reset clears DDRA[7:0], configuring all port A pins
as inputs.
1 = Corresponding port A pin configured as output
0 = Corresponding port A pin configured as input
NOTE
Avoid glitches on port A pins by writing to the port A data register before
changing data direction register A bits from 0 to 1.
MC68HC08AZ32A Data Sheet, Rev. 2
Freescale Semiconductor
155