MC908JL8CDWE Datasheet, PDF (153/212 Pages) Freescale Semiconductor, Inc – Microcontrollers

Port A
11.2 Port A
Port A is an 8-bit special function port that shares all of its pins with the keyboard interrupt (KBI) module
(see Chapter 13 Keyboard Interrupt Module (KBI)). Each port A pin also has software configurable pull-up
device if the corresponding port pin is configured as input port. PTA0–PTA5 and PTA7 has direct LED
drive capability.
NOTE
PTA0–PTA5 pins are available on 28-pin and 32-pin packages only.
PTA7 pin is available on 32-pin packages only.
11.2.1 Port A Data Register (PTA)
The port A data register (PTA) contains a data latch for each of the eight port A pins.
Address: $0000
Bit 7
6
5
4
3
2
Read:
PTA7
Write:
Reset:
PTA6
PTA5
PTA4
PTA3
PTA2
Unaffected by Reset
Additional Functions:
LED
(Sink)
pull-up
pull-up
LED
(Sink)
pull-up
LED
(Sink)
pull-up
LED
(Sink)
pull-up
LED
(Sink)
pull-up
Alternative Functions:
Keyboard
Interrupt
Keyboard
Interrupt
Keyboard
Interrupt
Keyboard
Interrupt
Keyboard
Interrupt
Keyboard
Interrupt
Figure 11-2. Port A Data Register (PTA)
1
PTA1
LED
(Sink)
pull-up
Keyboard
Interrupt
Bit 0
PTA0
LED
(Sink)
pull-up
Keyboard
Interrupt
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.
KBI7–KBI0 — Port A Keyboard Interrupts
The keyboard interrupt enable bits, KBIE[7:0], in the keyboard interrupt control register (KBIER) enable
the port A pins as external interrupt pins, (see Chapter 13 Keyboard Interrupt Module (KBI)).
11.2.2 Data Direction Register A (DDRA)
Data direction register A determines whether each port A pin is an input or an output. Writing a logic 1 to
a DDRA bit enables the output buffer for the corresponding port A pin; a logic 0 disables the output buffer.
NOTE
For those devices packaged in a 28-pin package, PTA7 is not connected.
DDRA7 should be set to a 1 to configure PTA7 as an output.
For those devices packaged in a 20-pin package, PTA0–PTA5 and PTA7
are not connected. DDRA0–DDRA5 and DDRA7 should be set to a 1 to
configure PTA0–PTA5 and PTA7 as outputs.
MC68HC908JL8/JK8 • MC68HC08JL8/JK8 • MC68HC908KL8 Data Sheet, Rev. 3.1
Freescale Semiconductor
153