Datasheet

© 2011 Microchip Technology Inc. DS70150E-page 59
dsPIC30F6010A/6015
8.0 I/O PORTS
All of the device pins (except VDD, VSS, MCLR and
OSC1/CLKI) are shared between the peripherals and
the parallel I/O ports.
All I/O input ports feature Schmitt Trigger inputs for
improved noise immunity.
8.1 Parallel I/O (PIO) Ports
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
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 the operation of the port pin. 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 (LATx). Reads from
the port (PORTx), read the port pins and writes to the
port pins, write the latch (LATx).
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 pin 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. Figure 8-1 shows the structure for a
dedicated port.
The format of the registers for PORTA are shown in
Table 8-1.
The TRISA register (Data Direction Control) controls
the direction of the RA<7:0> pins, as well as the INTx
pins and the V
REF pins. The LATA register supplies
data to the outputs and is readable/writable. Reading
the PORTA register yields the state of the input pins,
while writing the PORTA register modifies the contents
of the LATA register.
A parallel I/O (PIO) port that shares a pin with a periph-
eral is, in general, 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 pad cell. Figure 8-2 shows how ports are shared
with other peripherals, and the associated I/O cell (pad)
to which they are connected. Table 8-1 shows the
formats of the registers for the shared ports, PORTB
through PORTG.
FIGURE 8-1: BLOCK DIAGRAM OF A DEDICATED PORT STRUCTURE
Note: This data sheet summarizes features of
this group of dsPIC30F devices and is not
intended to be a complete reference
source. For more information on the CPU,
peripherals, register descriptions and
general device functionality, refer to the
“dsPIC30F Family Reference Manual”
(DS70046).
QD
CK
WR LAT+
TRIS Latch
I/O Pad
WR Port
Data Bus
QD
CK
Data Latch
Read LAT
Read Port
Read TRIS
WR TRIS
I/O Cell
Dedicated Port Module