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Advance Information
MC68HC705JJ7 MC68HC705JP7 — REV 4
90
Parallel Input/Output
MOTOROLA
Parallel Input/Output
7.4 Port B
Port B is an 8-bit, general-purpose, bidirectional I/O port with these
features:
Programmable pulldown devices
PB0–PB4 are shared with the analog subsystem.
PB3 and PB4 are shared with the 16-bit programmable timer.
PB4 can be driven directly by the output of comparator 1.
PB5–PB7 are shared with the simple serial interface (SIOP).
High current sinking capability on the PB4 pin
High current sourcing capability on the PB4 pin
7.4.1 Port B Data Register
The port B data register (PORTB) contains a bit for each of the port B
pins. When a port B pin is programmed to be an output, the state of its
data register bit determines the state of the output pin. When a port B pin
is programmed to be an input, reading the port B data register returns
the logic state of the pin. Reset has no effect on port B data.
PB0-PB7 — Port B 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 B. Reset has no effect on port B data.
Address:
$0001
Bit 7
6
5
4
3
2
1
Bit 0
Read:
PB7
PB6
PB5
PB4
PB3
PB2
PB1
PB0
Write:
Reset:
Unaffected by reset
Alternate:
SCK
SDI
SDO
AN4
AN3
AN2
AN1
AN0
Alternate:
SCK
SDI
SDO
TCMP
TCAP
AN2
AN1
AN0
Alternate:
SCK
SDI
SDO
CMP1
TCAP
AN2
AN1
AN0
Figure 7-5. Port B Data Register (PORTB)
F
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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