Datasheet

chipKIT™ WF32™ Board Reference Manual
Copyright Digilent, Inc. All rights reserved.
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Page 5 of 24
VU is the unregulated input voltage selected by the jumper setting jumper block J15.
5V0 is the connection to the VCC5V0 power bus on the WF32 board.
EN Ext is a signal provided to enable an external voltage regulator if one is being used. This would allow the sketch
running on the WF32 to turn on/off the external voltage regulator. When used with an external voltage regulator,
this allows the board to go into an extremely low power operating mode. This signal is connected to Port D, bit 13
(RD13) on the PIC32 microcontroller. This is accessible using digital pin 64.
GND is a connection to the digital ground bus on the WF32 board.
To completely disable operation of the on-board linear regulator, remove all shorting blocks from J16.
To use the on-board 5V regulator, use the provided shorting blocks to connect VU to LDO In, and to connect LDO
Out to 5V0, as follows:
LDO OutLDO In
VU 5V0
GNDEN Ext
Note: In this case, when J15 is in the EXT position, and J16 is jumpered to regulate the external input, do not apply
more than 18V. This can destroy the 5.0V regulator.
To bypass the on-board 5V regulator when powering the board from an externally regulator 5V power supply, such
as USB, Use one of the provided shorting blocks to connect VU to 5V0, as follows:
LDO OutLDO In
VU 5V0
GNDEN Ext
An external 5V regulator can be used. This would be desirable, for example, when operating from batteries. An
external switch mode 5V regulator could be used to provide higher power efficiency than the on-board linear
regulator. In this case, use wires as appropriate to connect VU to the unregulated input of the external regulator.
Connect the regulated 5V output to 5V0. Connect GND to the ground connection of the external regulator.
Optionally, connect EN Ext to the enable input control of the external regulator, if available. This allows the
external regulator to be turned off for low power operation. Digital pin 64 is then used to turn on/off the external
regulator.
The PIC32MX695 microcontroller is rated to use a maximum of 98mA of current when operating at 80Mhz. The
MRF24WG0MA WiFi module typically consumes a maximum of 237mA when transmitting. This allows
approximately 265mA of current to power the remaining 3.3V circuitry on the WF32 board and external circuitry
powered from the VCC3V3 bus. No circuitry on the WF32 board is powered from the VCC5V0 power bus, leaving
all current available from the 5V regulator to power external circuitry.
The POWER connector (J3) is used to power shields connected to the WF32 board. Pin 1 is unconnected, the
following pins are provided on this connector:
IOREF (pin 2): This pin is tied to the VCC3V3 bus.
P32_RST (pin 3): This connects to the MCLR pin on the PIC32 microcontroller and can be used to reset the PIC32.
VCC3V3 (pin 4): This routes the 3.3V power bus to shields.
VCC5V0 (pin 5): This routes the 5V power bus to shields.