Digilent MX3cK - Manual (Page 6)

Cerebot MX3cK Reference Manual
www.digilentinc.com page 6 of 23
Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners.
combined power used by the VCC5V0 bus and
the VCC3V3 bus should not exceed 925mA.
The Cerebot MX3cK can provide power to any
peripheral modules attached to the Pmod
connectors, JA-JE, and to I
2 C devices
connected to the I 2 C daisy chain connector,
J2. Each Pmod connector provides power pins
that can be powered from either the switched
main power bus, VCC5V0, or the regulated
voltage, VCC3V3, by setting the voltage
jumper block to the desired position.
The I
2 C power connector only provides 3.3V
from the VCC3V3 bus.
It is also possible to power the Cerebot MX3cK
from any one of the Pmod connectors or the
I
2
C connector. When powering the board from
a Pmod connector with the power select
jumper in the 5V0 position, a voltage applied at
the Pmod connector will power the VCC5V0
bus and be regulated to 3.3V for the VCC3V3
bus. When powering the board from the I
2 C
connector or a Pmod connector with the power
select jumper in the 3V3 position, only the
VCC3V3 bus will be powered and the VCC5V0
bus will not be powered.
Pmod™ Connectors
The Cerebot MX3cK 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 Cerebot MX3cK 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