Digilent 410-173-KIT - Manual (Page 3)

Cerebot 32MX4 Reference Manual
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Board Power Supply
The Cerebot 32MX4 may be USB powered via
either the USB debug port, or the USB device
port. Alternatively, the board may be powered
via dedicated, “external”, power supply
connectors.
There are three different power supply
connectors on Cerebot 32MX4 for connecting
an external power supply: J13, J14, and J18.
The barrel connector, J13, is useful for desktop
development and testing where using USB or
battery power is not suitable. J13 is the
connector used by the AC supply adapter
optionally available from Digilent, or other
sources. J13 is a 2.5mm x 5.5mm coaxial
connector wired with the center terminal as the
positive voltage.
J14 is a two-pin male header that provides
easy battery or battery-pack connection.
Digilent has both two-cell and four-cell AA
battery holders with two pin connectors
available for connection to J14.
J18 is a screw terminal connector for an
alternative power supply connection for use
with higher current battery packs, bench
supplies or other power sources where use of
a hard wired power supply is desirable.
The Cerebot 32MX4 is rated for external power
from 3.6 to 5 volts DC. Using voltage outside
this range could damage the board and
connected devices.
Connectors J13, J14, and J18 are wired in
parallel and connect to the “External Power”
position (center position) on the Power Select
jumper block J12. A shorting block should be
placed on the “External Power” position of J12
when using this option for board power. Only
one of these three power connectors should be
used at a time. If multiple power supplies are
connected simultaneously, damage to the
board or the power supplies may occur.
The output of power select jumper block J12 is
wired to one terminal of the power switch,
SW1. The other terminal of SW1 connects to
the unregulated power bus DBG_VU. The
DBG_VU bus provides the input to the voltage
regulator powering the in-system-programming
and debug subsystem.
The Cerebot 32MX4 has a second screw
terminal connector, J5 that supplies power to
the servo power bus, VS, to power the RC
hobby servo connectors. This allows servos to
be powered from a separate power supply than
the one powering the electronics on the
Cerebot 32MX4. This can be useful when
using servos that draw large amounts of
power.
Jumper JP1 can be used to connect the
Cerebot 32MX4 unregulated power bus VU to
the servo power bus, VS. When no shorting
block is installed on JP1, the VU and VS
busses are separate. When a shorting block is
on JP1, the two busses are joined and the VU
bus can be powered in any of the previously
indicated ways, or from connector J5.
The Cerebot 32MX4 can provide power to any
peripheral modules attached to the Pmod
connectors and to I2C devices powered from
the I2C daisy chain connectors, J2 and J6.
Each Pmod connector provides power pins
that can be powered by either unregulated
voltage, VU, or regulated voltage, VCC, by
setting the voltage jumper block to the desired
position. The I2C power connectors only
provide regulated voltage, VCC.
The PIC32 microcontroller and on-board I/O
devices operate at a supply voltage of 3.3V
provided by the VCC bus. The regulated
voltage on the VCC bus is provided by an on-
board voltage regulator. This regulator is
capable of providing a maximum of 500mA of
current. The PIC32 microcontroller will use
approximately 55mA when running at 80MHz.
The remaining current is available to provide
power to attached Pmod and I2C devices. The
regulator is on the bottom of the board, near
the power connectors, and will get warm when