MC68HC908QT4CPE Datasheet, PDF (106/192 Pages) Motorola, Inc – M68HC08 Microcontrollers

Input/Output Ports (PORTS)
12.2 Port A
NOTE:
Port A is a 6-bit special function port that shares all six of its pins with the keyboard
interrupt (KBI) module (see Section 9. 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.
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 0. In this case, the BIH and BIL
instructions can be used to read the logic level on the PTA2 pin. When the IRQ
function is disabled, these instructions will behave as if the PTA2 pin is a logic 1.
However, reading bit 2 of PTA will read the actual logic level on the pin.
12.2.1 Port A Data Register
The port A data register (PTA) contains a data latch for each of the six port A pins.
Address: $0000
Bit 7
Read:
R
Write:
Reset:
Additional Functions:
6
AWUL
5
PTA5
KBI5
4
3
PTA4
PTA3
Unaffected by reset
KBI4
KBI3
2
PTA2
KBI2
1
PTA1
KBI1
Bit 0
PTA0
KBI0
R
= Reserved
= Unimplemented
Figure 12-2. Port A Data Register (PTA)
PTA[5:0] — 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.
AWUL — Auto Wakeup Latch Data Bit
This is a read-only bit which has the value of the auto wakeup interrupt request
latch. The wakeup request signal is generated internally (see Section 4. Auto
Wakeup Module (AWU)). There is no PTA6 port nor any of the associated bits
such as PTA6 data register, pullup enable or direction.
KBI[5:0] — Port A Keyboard Interrupts
The keyboard interrupt enable bits, KBIE5–KBIE0, in the keyboard interrupt
control enable register (KBIER) enable the port A pins as external interrupt pins
(see Section 9. Keyboard Interrupt Module (KBI)).
Data Sheet
106
Input/Output Ports (PORTS)
MC68HC908QY/QT Family — Rev. 3
MOTOROLA