Microchip Technology MA330027 Data Sheet
2009-2012 Microchip Technology Inc.
DS70616G-page 207
dsPIC33EPXXX(GP/MC/MU)806/810/814 and PIC24EPXXX(GP/GU)810/814
11.0 I/O PORTS
All of the device pins (except V
DD
, V
SS
, MCLR and
OSC1/CLKI) are shared among the peripherals and the
parallel I/O ports. All I/O input ports feature Schmitt
Trigger inputs for improved noise immunity.
parallel I/O ports. All I/O input ports feature Schmitt
Trigger inputs for improved noise immunity.
11.1
Parallel I/O (PIO) Ports
Generally, a parallel I/O port that shares a pin with a
peripheral is subservient to the peripheral. The
peripheral’s output buffer data and control signals are
provided to a pair of multiplexers. The multiplexers
select whether the peripheral or the associated port
has ownership of the output data and control signals of
the I/O pin. The logic also prevents “loop through,” in
which a port’s digital output can drive the input of a
peripheral that shares the same pin.
peripheral is subservient to the peripheral. The
peripheral’s output buffer data and control signals are
provided to a pair of multiplexers. The multiplexers
select whether the peripheral or the associated port
has ownership of the output data and control signals of
the I/O pin. The logic also prevents “loop through,” in
which a port’s digital output can drive the input of a
peripheral that shares the same pin.
illus-
trates how ports are shared with other peripherals and
the associated I/O pin to which they are connected.
the associated I/O pin to which they are connected.
When a peripheral is enabled and the peripheral is
actively driving an associated pin, the use of the pin as
a general purpose output pin is disabled. The I/O pin
can be read, but the output driver for the parallel port bit
is disabled. If a peripheral is enabled, but the peripheral
is not actively driving a pin, that pin can be driven by a
port.
All port pins have eight registers directly associated
with their operation as digital I/O. The Data Direction
register (TRISx) determines whether the pin is an input
or an output. If the data direction bit is a ‘1’, then the pin
is an input. All port pins are defined as inputs after a
Reset. Reads from the latch (LATx) read the latch.
Writes to the latch write the latch. Reads from the port
(PORTx) read the port pins, while writes to the port pins
write the latch.
Any bit and its associated data and control registers
that are not valid for a particular device is disabled. This
means the corresponding LATx and TRISx registers
and the port pin are read as zeros.
When a pin is shared with another peripheral or
function that is defined as an input only, it is
nevertheless regarded as a dedicated port because
there is no other competing source of outputs.
actively driving an associated pin, the use of the pin as
a general purpose output pin is disabled. The I/O pin
can be read, but the output driver for the parallel port bit
is disabled. If a peripheral is enabled, but the peripheral
is not actively driving a pin, that pin can be driven by a
port.
All port pins have eight registers directly associated
with their operation as digital I/O. The Data Direction
register (TRISx) determines whether the pin is an input
or an output. If the data direction bit is a ‘1’, then the pin
is an input. All port pins are defined as inputs after a
Reset. Reads from the latch (LATx) read the latch.
Writes to the latch write the latch. Reads from the port
(PORTx) read the port pins, while writes to the port pins
write the latch.
Any bit and its associated data and control registers
that are not valid for a particular device is disabled. This
means the corresponding LATx and TRISx registers
and the port pin are read as zeros.
When a pin is shared with another peripheral or
function that is defined as an input only, it is
nevertheless regarded as a dedicated port because
there is no other competing source of outputs.
Note 1: This data sheet summarizes the features
of the dsPIC33EPXXX(GP/MC/MU)806/
810/814 and PIC24EPXXX(GP/GU)810/
814 families of devices. It is not intended
to be a comprehensive reference source.
To complement the information in this
data sheet, refer to Section 10. “I/O
Ports” (DS70598) of the “dsPIC33E/
PIC24E Family Reference Manual”,
which is available from the Microchip web
site (
810/814 and PIC24EPXXX(GP/GU)810/
814 families of devices. It is not intended
to be a comprehensive reference source.
To complement the information in this
data sheet, refer to Section 10. “I/O
Ports” (DS70598) of the “dsPIC33E/
PIC24E Family Reference Manual”,
which is available from the Microchip web
site (
www.microchip.com
).
2: Some registers and associated bits
described in this section may not be
available on all devices. Refer to
available on all devices. Refer to
in
this data sheet for device-specific register
and bit information.
and bit information.