Output Compare; Input Capture - Digilent chipKIT Pro MX7 Reference Manual

chipKIT™ Pro MX7 Board Reference Manual

14 Output Compare

The PIC32MX795 microcontroller provides five output compare units that can be used to control the timing of
state changes on certain output pins or to generate pulse width modulated (PWM) outputs.
Each output compare unit works with a particular output pin (OC1-OC5). It can be programmed to control the pin
in any of the following ways:
 PWM output
 Generate continuous pulses
 Generate a single pulse
 Toggle the output pin
 Generate falling edge
 Generate rising edge
The output compare units work in conjunction with a timer. Either Timer2 or Timer3 can be used with any of the
five output compare units.
Refer to the PIC32 Family Reference Manual, Section 16, Output Compare for detailed information on the use of
the output compare units.
When using the MPIDE software, these are accessed using the analogWrite() function. The digital pin number, or
preferably, the symbols PIN_OC1 through PIN_OC5 are used to specify the pin. The MPIDE software currently only
supports using the output compare units to generate PWM outputs. It uses Timer2 to control the output
compares.
The following gives Pmod port position, chipKIT pin number, and microcontroller I/O port and bit number for the
output compare unit's output pins:
 OC1 – JD-02, digital pin 25, RD00
 OC2 – JD-07, digital pin 28, RD01
 OC3 – JD-08, digital pin 29, RD02
 OC4 – JD-09, digital pin 30, RD03
 OC5 – JC-09, digital pin 22, RD04

15 Input Capture

The PIC32MX795 microcontroller provides five input capture units. The design of the chipKIT Pro MX7 board allows
the use of three of them.
An input capture unit works in conjunction with a timer and monitors the state of an associated pin. When the pin
changes state, the current value of the timer is captured. The input capture units can be used with either Timer2 or
Timer3.
The input capture unit can be programmed to be sensitive to either a rising edge, a falling edge, or both edges on
the input pin. An interrupt can also be signaled when an input capture is triggered. Each input capture has a four
level deep FIFO that can buffer up to four capture events.
For detailed information on the operation and use of the input capture units, refer to the PIC32 Family Reference
Manual, Section 15, Input Capture.
The following gives the Pmod port position, chipKIT pin number, and microcontroller port and bit number for the
input capture units input pins:
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