dsPIC33FJ32MC204 Microchip Technology, dsPIC33FJ32MC204 Datasheet - Page 111

• Manufacturer Part Number: dsPIC33FJ32MC204
• Description: (dsPIC33FJ16MC304 / dsPIC33FJ32MC20x) 16-bit Microcontrollers
• Manufacturer: Microchip Technology

9.4
Peripheral pin select configuration enables peripheral
set selection and placement on a wide range of I/O
pins. By increasing the pinout options available on a
particular device, programmers can better tailor the
microcontroller to their entire application, rather than
trimming the application to fit the device.
The peripheral pin select configuration feature oper-
ates over a fixed subset of digital I/O pins. Program-
mers can independently map the input and/or output of
most digital peripherals to any one of these I/O pins.
Peripheral pin select is performed in software, and gen-
erally does not require the device to be reprogrammed.
Hardware safeguards are included that prevent acci-
dental or spurious changes to the peripheral mapping,
once it has been established.
9.4.1
The peripheral pin select feature is used with a range
of up to 26 pins. The number of available pins depends
on the particular device and its pin count. Pins that
support the peripheral pin select feature include the
designation “RPn” in their full pin designation, where
"RP" designates a remappable peripheral and “n” is the
remappable pin number.
9.4.2
The peripherals managed by the peripheral pin select
feature are all digital-only peripherals. These include:
• General serial communications (UART and SPI)
• General purpose timer clock inputs
• Timer-related peripherals (input capture and
• Interrupt-on-change inputs
In comparison, some digital-only peripheral modules
are never included in the peripheral pin select feature.
This is because the peripheral’s function requires spe-
cial I/O circuitry on a specific port and cannot be easily
connected to multiple pins. These modules include I
A similar requirement excludes all modules with analog
inputs, such as the Analog-to-Digital Converter (ADC).
© 2007 Microchip Technology Inc.
output compare)
Peripheral Pin Select
AVAILABLE PINS
AVAILABLE PERIPHERALS
Preliminary
2
C.
Remappable peripherals are not associated with a
default I/O pin. The peripheral must always be
assigned to a specific I/O pin before it can be used. In
contrast, non remappable peripherals are always avail-
able on a default pin, assuming that the peripheral is
active and not conflicting with another peripheral.
9.4.2.1
When a remappable peripheral is active on a given I/O
pin, it takes priority over all other digital I/O and digital
communication peripherals associated with the pin.
Priority is given regardless of the type of peripheral that
is mapped. Remappable peripherals never take priority
over any analog functions associated with the pin.
9.4.3
Peripheral pin select features are controlled through
two sets of special function registers: one to map
peripheral inputs, and one to map outputs. Because
they are separately controlled, a particular peripheral’s
input and output (if the peripheral has both) can be
placed on any selectable function pin without
constraint.
The association of a peripheral to a peripheral select-
able pin is handled in two different ways, depending on
whether an input or output is being mapped.
9.4.3.1
The inputs of the peripheral pin select options are
mapped on the basis of the peripheral. A control regis-
ter associated with a peripheral dictates the pin it will be
mapped to. The RPINRx registers are used to config-
ure peripheral input mapping (see Register 9-1 through
Register 9-13). Each register contains sets of 5-bit
fields, with each set associated with one of the remap-
pable peripherals. Programming a given peripheral’s
bit field with an appropriate 5-bit value maps the RPn
pin with that value to that peripheral. For any given
device, the valid range of values for any bit field corre-
sponds to the maximum number of peripheral pin
selections supported by the device.
Figure 9-2 Illustrates remappable pin selection for
U1RX input.
CONTROLLING PERIPHERAL PIN
SELECT
Peripheral Pin Select Function
Priority
Input Mapping
DS70283B-page 109