Microchip Technology DM240015 Data Sheet
PIC24FJ128GC010 FAMILY
DS30009312B-page 192
2012-2013 Microchip Technology Inc.
11.4
Peripheral Pin Select (PPS)
A major challenge in general purpose devices is provid-
ing the largest possible set of peripheral features while
minimizing the conflict of features on I/O pins. In an
application that needs to use more than one peripheral
multiplexed on a single pin, inconvenient work arounds
in application code, or a complete redesign, may be the
only option.
The Peripheral Pin Select (PPS) feature provides an
alternative to these choices by enabling the user’s
peripheral set selection and its placement on a wide
range of I/O pins. By increasing the pinout options
available on a particular device, users can better tailor
the microcontroller to their entire application, rather
than trimming the application to fit the device.
The Peripheral Pin Select feature operates over a fixed
subset of digital I/O pins. Users may independently
map the input and/or output of any one of many digital
peripherals to any one of these I/O pins. PPS is per-
formed in software and generally does not require the
device to be reprogrammed. Hardware safeguards are
included that prevent accidental or spurious changes to
the peripheral mapping once it has been established.
ing the largest possible set of peripheral features while
minimizing the conflict of features on I/O pins. In an
application that needs to use more than one peripheral
multiplexed on a single pin, inconvenient work arounds
in application code, or a complete redesign, may be the
only option.
The Peripheral Pin Select (PPS) feature provides an
alternative to these choices by enabling the user’s
peripheral set selection and its placement on a wide
range of I/O pins. By increasing the pinout options
available on a particular device, users can better tailor
the microcontroller to their entire application, rather
than trimming the application to fit the device.
The Peripheral Pin Select feature operates over a fixed
subset of digital I/O pins. Users may independently
map the input and/or output of any one of many digital
peripherals to any one of these I/O pins. PPS is per-
formed in software and generally does not require the
device to be reprogrammed. Hardware safeguards are
included that prevent accidental or spurious changes to
the peripheral mapping once it has been established.
11.4.1
AVAILABLE PINS
The PPS feature is used with a range of up to 44 pins,
depending on the particular device and its pin count.
Pins that support the Peripheral Pin Select feature
include the designation, “RPn” or “RPIn”, in their full pin
designation, where “n” is the remappable pin number.
“RP” is used to designate pins that support both remap-
pable input and output functions, while “RPI” indicates
pins that support remappable input functions only.
PIC24FJ128GC010 family devices support a larger
number of remappable input only pins than remappable
input/output pins. In this device family, there are up to
32 remappable input/output pins, depending on the pin
count of the particular device selected. These pins are
numbered, RP0 through RP31. Remappable input only
pins are numbered above this range, from RPI32 to
RPI43 (or the upper limit for that particular device).
See
depending on the particular device and its pin count.
Pins that support the Peripheral Pin Select feature
include the designation, “RPn” or “RPIn”, in their full pin
designation, where “n” is the remappable pin number.
“RP” is used to designate pins that support both remap-
pable input and output functions, while “RPI” indicates
pins that support remappable input functions only.
PIC24FJ128GC010 family devices support a larger
number of remappable input only pins than remappable
input/output pins. In this device family, there are up to
32 remappable input/output pins, depending on the pin
count of the particular device selected. These pins are
numbered, RP0 through RP31. Remappable input only
pins are numbered above this range, from RPI32 to
RPI43 (or the upper limit for that particular device).
See
for a summary of pinout options in each
package offering.
11.4.2
AVAILABLE PERIPHERALS
The peripherals managed by the PPS are all digital
only peripherals. These include general serial commu-
nications (UART and SPI), general purpose timer clock
inputs, timer related peripherals (input capture and out-
put compare) and external interrupt inputs. Also
included are the outputs of the comparator module,
since these are discrete digital signals.
only peripherals. These include general serial commu-
nications (UART and SPI), general purpose timer clock
inputs, timer related peripherals (input capture and out-
put compare) and external interrupt inputs. Also
included are the outputs of the comparator module,
since these are discrete digital signals.
PPS is not available for these peripherals:
• I
• I
2
C™ (input and output)
• USB (all module inputs and outputs)
• Change Notification inputs
• RTCC alarm output(s)
• EPMP signals (input and output)
• LCD signals
• Analog (inputs and outputs)
• INT0
A key difference between pin select and non-pin select
peripherals is that pin select peripherals are not asso-
ciated 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-pin select peripherals are always
available on a default pin, assuming that the peripheral
is active and not conflicting with another peripheral.
• Change Notification inputs
• RTCC alarm output(s)
• EPMP signals (input and output)
• LCD signals
• Analog (inputs and outputs)
• INT0
A key difference between pin select and non-pin select
peripherals is that pin select peripherals are not asso-
ciated 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-pin select peripherals are always
available on a default pin, assuming that the peripheral
is active and not conflicting with another peripheral.
11.4.2.1
Peripheral Pin Select Function
Priority
Priority
Pin-selectable peripheral outputs (e.g., OC, UART
transmit) will take priority over general purpose digital
functions on a pin, such as EPMP and port I/O. Special-
ized digital outputs (e.g., USB on USB-enabled
devices) will take priority over PPS outputs on the same
pin. The pin diagrams list peripheral outputs in the
order of priority. Refer to them for priority concerns on
a particular pin.
Unlike PIC24F devices with fixed peripherals,
pin-selectable peripheral inputs will never take owner-
ship of a pin. The pin’s output buffer will be controlled
by the TRISx setting or by a fixed peripheral on the pin.
If the pin is configured in Digital mode, then the PPS
input will operate correctly. If an analog function is
enabled on the pin, the PPS input will be disabled.
transmit) will take priority over general purpose digital
functions on a pin, such as EPMP and port I/O. Special-
ized digital outputs (e.g., USB on USB-enabled
devices) will take priority over PPS outputs on the same
pin. The pin diagrams list peripheral outputs in the
order of priority. Refer to them for priority concerns on
a particular pin.
Unlike PIC24F devices with fixed peripherals,
pin-selectable peripheral inputs will never take owner-
ship of a pin. The pin’s output buffer will be controlled
by the TRISx setting or by a fixed peripheral on the pin.
If the pin is configured in Digital mode, then the PPS
input will operate correctly. If an analog function is
enabled on the pin, the PPS input will be disabled.
11.4.3
CONTROLLING PERIPHERAL PIN
SELECT
SELECT
PPS features are controlled through two sets of Special
Function Registers (SFRs): one to map peripheral
inputs and one to map the 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-selectable pin is handled in two different
ways, depending on if an input or an output is being
mapped.
Function Registers (SFRs): one to map peripheral
inputs and one to map the 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-selectable pin is handled in two different
ways, depending on if an input or an output is being
mapped.