Freescale Semiconductor MC68HC08KH12 - Manual (Page 186)

Advance Information MC68HC(7)08KH12 — Rev. 1.1
186 Freescale Semiconductor
12.3 Port A
Port A is an 8-bit general-purpose bidirectional I/O port with software
configurable pullups.
12.3.1 Port A Data Register (PTA)
The port A data register contains a data latch for each of the eight port
A pins.
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.
The port A pullup enable bit, PAP, in the port option control register
(POC) enables pullups on port A pins if the respective pin is configured
as an input.
(See 12.9 Port Options .)
12.3.2 Data Direction Register A (DDRA)
Data direction register A determines whether each port A pin is an input
or an output. Writing a logic one to a DDRA bit enables the output buffer
for the corresponding port A pin; a logic zero disables the output buffer.
Address: $0000
Bit 7 6 5 4 3 2 1 Bit 0
Read:
PTA7 PTA6 PTA5 PTA4 PTA3 PTA2 PTA1 PTA0
Write:
Reset: Unaffected by reset
Figure 12-1. Port A Data Register (PTA)