
Input/Output Ports (PORTS)
Data Sheet
MC68HLC908QY/QT Family — Rev. 2
104
Input/Output Ports (PORTS)
MOTOROLA
12.2 Port A
Port A is a 6-bit special function port that shares all six of its pins with the keyboard
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 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.
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
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
Address: $0000
Bit 7
6
543
21
Bit 0
Read:
R
AWUL
PTA5
PTA4
PTA3
PTA2
PTA1
PTA0
Write:
Reset:
Unaffected by reset
Additional Functions:
KBI5
KBI4
KBI3
KBI2
KBI1
KBI0
R= Reserved
= Unimplemented
Figure 12-2. Port A Data Register (PTA)
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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