Digilent MX7cK User Manual

Page 21

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Cerebot MX7cK Reference Manual

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page 21 of 36

External Interrupts

The PIC32 microcontroller provides five
external interrupt inputs. An external interrupt
input can be used to generate an interrupt to
the microprocessor CPU when the pin changes
state. They can be programmed to interrupt on
a rising edge or a falling edge on the pin.

Refer to the PIC32 Family Reference Manual,
Section 8, Interrupts for more information on
the operation of the external interrupts.

These are accessed using the attachInterrupt()
and detachInterrupt() functions when using the
chipKIT MPIDE software. The interrupt number
is specified using the numbers 0-4, or
preferably, the symbols EXT_INT0 through
EXT_INT4. The symbols PIN_INT0 through
PIN_INT4 are also defined to refer to the digital
pin numbers used for the external interrupt
inputs.

The following gives connector position, chipKIT
pin number, and microcontroller I/O port and
bit number. Note that INT0-INT1 are on Pmod
connectors. INT3 and INT4 are on I2C1 daisy
chain connector J7. When using these pins as
external interrupt inputs, they are not available
to use for I

C. It may also be necessary to

disable the pull-ups by pulling the shorting
blocks from JP3 or JP4.



INT0

– JD-02, digital pin 25, RD00



INT1

– JE-07, digital pin 36, RE08



INT2

– JF-07, digital pin 44, RE09



INT3

– J7-1 & J7-2, digital pin 57, RA14



INT4

– J7-3 & J7-4, digital pin 58, RA15

RTCC

The PIC32 microcontroller contains a low
frequency oscillator and Real Time
Clock/Calendar circuit, RTCC, that can be
used to maintain time and date information.
The operation of the RTCC requires a
32.768Khz frequency source. The crystal X2
position, just above and on the right of the
PIC32 microcontroller, IC1, is provided for the
user to solder in a 32Khz watch crystal. The

Citizen CFS206-32.768KDZF-UB is a crystal
part that can be used in this location.

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