Freescale Semiconductor, Inc.
Parallel Input/Output (I/O)
7.3 Port A
Port A is an 8-bit, general-purpose, bidirectional input/output (I/O) port.
7.3.1 Port A Data Register
The port A data register (PORTA) shown in Figure 7-1 contains a data
latch for each of the eight port A pins. When a port A pin is programmed
to be an output, the state of its data register bit determines the state of
the output pin. When a port A pin is programmed to be an input, reading
the port A data register returns the logic state of the pin.
Address: $0000
Bit 7
6
5
4
3
2
1
Bit 0
PA0
Read:
Write:
Reset:
PA7
PA6
PA5
PA4
PA3
PA2
PA1
Unaffected by reset
Figure 7-1. Port A Data Register (PORTA)
PA7–PA0 — Port A Data Bits
These read/write bits are software programmable. Data direction of
each bit is under the control of the corresponding bit in data direction
register A. Reset has no effect on port A data.
Technical Data
78
MC68HC705C8A — Rev. 3
Parallel Input/Output (I/O)
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