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chipKIT™ MX3 Board Reference Manual
Copyright Digilent, Inc. All rights reserved.
Other product and company names mentioned may be trademarks of their respective owners.
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2.1 RESET
A reset button is at the upper left corner of the board. Pressing this button will reset the PIC32 microcontroller.
3
Pmod™ Connectors
The chipKIT MX3 has five connectors for connecting Digilent Pmod peripheral modules. The Pmod connectors,
labeled JA–JF, are 2x8 right-angle, female pin header connectors. Each connector has an associated power select
jumper block labeled JPA–JPF.
Digilent Pmods are a line of small peripheral modules that provide various kinds of I/O interfaces. The Pmod
product line includes such things as button, switch and LED modules, connector modules, LCD displays, high
current output drivers, and many others.
There are two styles of Pmod connector: six-pin and twelve-pin. Both connectors use standard pin headers with
100mil spaced pins. The six-pin connectors have the pins in a 1x6 configuration, while the twelve-pin connectors
use a 2x6 configuration. All of the Pmod connectors on the chipKIT MX3 are twelve pin connectors.
The six-pin connectors provide four I/O signals, ground and a switchable power connection. The twelve-pin
connectors provide eight I/O signals, two power and two ground pins. The twelve-pin connectors have the signals
arranged so that one twelve-pin connector is equivalent to two of the six-pin connectors. Pins 1–4 and 7–10 are
the signal pins, pins 5 and 11 are the ground pins and pins 6 & 12 are the power supply pins.
The pin numbering that Digilent uses on the twelve-pin Pmod connectors is non-standard. The upper row of pins
are numbered 1–6, left to right (when viewed from the top of the board), and the lower row of pins are numbered
7–12, left to right. This is in keeping with the convention that the upper and lower rows of pins can be considered
to be two six-pin connectors stacked. When viewed from the end of the connector, pin 1 is the upper right pin and
pin 7 is immediately below it (closer to the PCB).
Each Pmod connector has an associated power select jumper. These are used to select the power supply voltage
supplied to the power supply pin on the Pmod connector. They are switchable between either the regulated 5V
power supply or the 3.3V main board supply. Place the shorting block in the 3V3 position for regulated 3.3V and in
the 5V0 position for regulated 5V. Note that the 5V0 position will supply the unregulated input supply if the
regulator bypass jumper JP2 is in the BYP position.
Each signal pin on the Pmod connectors is connected to an input/output pin on the PIC32 microcontroller. Each pin
has a 200 ohm series resistor and an ESD protection diode. The series resistor provides short circuit protection to
prevent damaging the I/O block in the microcontroller if the pin is inadvertently shorted to VDD or GND, or two
outputs are shorted together. The ESD protection diode protects the I/O block from damage due to electro-static
discharge.
Although ESD protection is provided between the connector pins and the microcontroller pins, ESD safe handling
procedures should be followed when handling the circuit board. The pins on the microcontroller and other circuits
on the board are exposed and can be damaged through ESD when handling the board.
Digilent Pmod peripheral modules can either be plugged directly into the connectors on the chipKIT MX3 or
attached via cables. Digilent has a variety of Pmod interconnect cables available.