Datasheet

Input/Output Ports (I/O)
Port A
MC68HC908GR8 — Rev 4.0 Technical Data
MOTOROLA Input/Output Ports (I/O) 209
16.3 Port A
Port A is an 4-bit special-function port that shares all four of its pins with
the keyboard interrupt (KBI) module. Port A also has software
configurable pullup devices if configured as an input port.
16.3.1 Port A Data Register
The port A data register (PTA) contains a data latch for each of the four
port A pins.
PTA3–PTA0 — 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.
KBD3–KBD0 — Keyboard Inputs
The keyboard interrupt enable bits, KBIE3–KBIE0, in the keyboard
interrupt control register (KBICR) enable the port A pins as external
interrupt pins. See Keyboard Interrupt (KBI).
Address: $0000
Bit 7654321Bit 0
Read: 0000
PTA3 PTA2 PTA1 PTA0
Write:
Reset: Unaffected by reset
Alternate
Function:
KBD3 KBD2 KBD1 KBD0
Figure 16-2. Port A Data Register (PTA)
Frees
cale Semiconductor,
I
Freescale Semiconductor, Inc.
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