MC68HC705P9 Datasheet, PDF (83/160 Pages) Motorola, Inc – HCMOS Microcontroller Unit

7.3 Port A
Freescale Semiconductor, Inc.
Parallel Input/Output (I/O) Ports
Port A
Port A is an 8-bit general-purpose I/O port.
7.3.1 Port A Data Register (PORTA)
The port A data register contains a latch for each of the eight port A pins.
$0000 Bit 7
6
5
4
3
2
1
Bit 0
Read:
PA7
PA6
PA5
PA4
PA3
PA2
PA1
PA0
Write:
Reset:
Unaffected by reset
Figure 7-2. Port A Data Register (PORTA)
PA[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.
7.3.2 Data Direction Register A (DDRA)
Data direction register A determines whether each port A pin is an input
or an output.
$0004
Read:
Write:
Reset:
Bit 7
6
5
4
3
2
1
DDRA7 DDRA6 DDRA5 DDRA4 DDRA3 DDRA2 DDRA1
0
0
0
0
0
0
0
Figure 7-3. Data Direction Register A (DDRA)
Bit 0
DDRA0
0
DDRA[7:0] — Data Direction Register A Bits
These read/write bits control port A data direction. Reset clears
DDRA[7:0], configuring all eight port A pins as inputs.
1 = Corresponding port A pin configured as output
0 = Corresponding port A pin configured as input
MC68HC705P9 — Rev. 4.0
MOTOROLA
Parallel Input/Output (I/O) Ports
For More Information On This Product,
Go to: www.freescale.com
Technical Data
83