DSPIC30F6011A_06 Datasheet, PDF (65/238 Pages) Microchip Technology – High-Performance, 16-Bit Digital Signal Controllers

dsPIC30F6011A/6012A/6013A/6014A
8.0 I/O PORTS
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).
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 dis-
abled. 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.
The format of the registers for PORTA are shown in
Table 8-1.
The TRISA (Data Direction Control) register controls
the direction of the RA<7:0> pins, as well as the INTx
pins and the VREF 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 8-2 through
Table 8-9 show the formats of the registers for the
shared ports, PORTB through PORTG.
Note: The actual bits in use vary between
devices.
FIGURE 8-1:
BLOCK DIAGRAM OF A DEDICATED PORT STRUCTURE
Dedicated Port Module
Read TRIS
Data Bus
WR TRIS
WR LAT +
WR Port
TRIS Latch
DQ
CK
Data Latch
DQ
CK
I/O Cell
I/O Pad
Read LAT
Read Port
© 2006 Microchip Technology Inc.
Preliminary
DS70143C-page 63