PIC24HJ64GP506-I Datasheet, PDF (141/292 Pages) Microchip Technology – High-Performance, 16-Bit Microcontrollers

PIC24HJXXXGPX06/X08/X10
11.0 I/O PORTS
Note:
This data sheet summarizes the features
of the PIC24HJXXXGPX06/X08/X10 fam-
ily of devices. However, it is not intended
to be a comprehensive reference source.
To complement the information in this data
sheet, refer to the “PIC24H Family Refer-
ence Manual”, Section 10. “I/O Ports”
(DS70230), which is available from the
Microchip website (www.microchip.com).
All of the device pins (except VDD, VSS, MCLR and
OSC1/CLKIN) are shared between the peripherals and
the parallel I/O ports. All I/O input ports feature Schmitt
Trigger inputs for improved noise immunity.
11.1 Parallel I/O (PIO) Ports
A parallel I/O port that shares a pin with a peripheral is,
in general, subservient to the peripheral. The periph-
eral’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. Figure 11-1 shows
how ports are shared with other peripherals and the
associated I/O pin to which they are connected.
When a peripheral is enabled and actively driving an
associated pin, the use of the pin as a general purpose
output pin is disabled. The I/O pin may be read, but the
output driver for the parallel port bit will be disabled. If
a peripheral is enabled, but the peripheral is not
actively driving a pin, that pin may be driven by a port.
All port pins have three 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 will be
disabled. That means the corresponding LATx and
TRISx registers and the port pins will read as zeros.
When a pin is shared with another peripheral or func-
tion that is defined as an input only, it is nevertheless
regarded as a dedicated port because there is no
other competing source of outputs. An example is the
INT4 pin.
Note: The voltage on a digital input pin can be
between -0.3V to 5.6V.
FIGURE 11-1:
BLOCK DIAGRAM OF A TYPICAL SHARED PORT STRUCTURE
Peripheral Module
Output Multiplexers
Peripheral Input Data
Peripheral Module Enable
Peripheral Output Enable
Peripheral Output Data
I/O
1 _{Output Enable}
0
PIO Module
Read TRIS
1 _{Output Data}
0
Data Bus
WR TRIS
WR LAT +
WR PORT
Read LAT
DQ
CK
TRIS Latch
D
Q
CK
Data Latch
Read Port
I/O Pin
Input Data
© 2009 Microchip Technology Inc.
DS70175H-page 139