MC68HC705K1 Datasheet, PDF (64/140 Pages) Freescale Semiconductor, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
Parallel Input/Output (I/O)
7.3 I/O Port Function
The 10 bidirectional input/output (I/O) pins form two parallel I/O ports.
Each I/O pin is programmable as an input or an output. The contents of
the data direction registers determine the data direction of each I/O pin.
All 10 I/O pins have software-programmable pulldown devices.
7.4 Port A
Port A is an 8-bit, general-purpose, bidirectional I/O port with these
features:
• Programmable pulldown devices
• 8-mA current sinking capability (pins PA7–PA4)
• External interrupt capability (pins PA3–PA0)
7.4.1 Port A Data Register
The port A data register (PORTA) contains a bit for each of the 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
Read:
PA7
PA6
PA5
PA4
PA3
PA2
PA1
PA0
Write:
Reset:
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
Parallel Input/Output (I/O)
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MC68HC705K1 — Rev. 2.0