Datasheet

chipKIT™ Wi-FIRE™ Board Reference Manual

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2 MPIDE and USB Serial Communications

The Wi-FIRE board is designed to be used with the MPIDE; the MPIDE development platform was created by

modifying the Arduino IDE and is backwards-compatible with the Arduino IDE. Links for where to obtain the MPIDE

installation files, as well as instructions for installing MPIDE, can be found at www.chipkit.net/started.

The MPIDE uses a serial communications port to communicate with a boot loader running on the Wi-FIRE board.

The serial port on the Wi-FIRE board is implemented using an FTDI FT232RQ USB serial converter. Before

attempting to use the MPIDE to communicate with the Wi-FIRE, the appropriate USB device driver must be

installed.

The Wi-FIRE board uses a standard mini-USB connector. Generally, a USB A to mini-B cable is used for connection

to a USB port on the PC.

When the MPIDE needs to communicate with the Wi-FIRE board, the board is reset and starts running the boot

loader. The MPIDE then establishes communications with the boot loader and uploads the program to the board.

When the MPIDE opens the serial communications connection on the PC, the DTR pin on the FT232RQ chip is

driven low. This pin is coupled through a capacitor to the MCLR pin on the PIC32 microcontroller. Driving the MCLR

line low resets the microcontroller, which restarts the execution with the boot loader.

This automatic reset action (when the serial communications connection is opened) can be disabled. To disable

this operation, there is a jumper labeled JP2, which can be disconnected. JP2 is normally shorted, but if the

shorting block is removed, the automatic reset operation will be disabled.

Two red LEDs (LD5 and LD6) will blink when data is being sent or received between the Wi-FIRE and the PC over

the serial connection.

The header connector J4 provides access to the other serial handshaking signals provided by the FT232RQ.

Connector J4 is not loaded at the factory and can be installed by the user to access these signals.

3 Power Supply

The Wi-FIRE is designed to be powered via USB (J1), from an external power supply (J14 or J15), or from the USB

OTG receptacle (J11). Jumper block J16 is used to select which power supply is used. The power supply voltage

selected by J16 is applied to the unregulated power bus, VU.

In order to operate the Wi-FIRE as a USB device powered from the USB serial interface (connector J1), place a

shorting block in the UART position of jumper block J16. To operate the Wi-FIRE from an external power supply,

attach the power supply to either J14 or J15 and place a shorting block in the EXT position of J16. Be sure to

observe correct polarity when connecting a power supply to J14, as a reversed connection could damage the

board. To operate the Wi-FIRE as a USB powered device from the USB OTG connector (J11), place a shorting block

on the USB position of J16. This will normally only be done when running a sketch on the board that programs it to

operate as a USB device. The power supply section in the Wi-FIRE provides two voltage regulators, a 3.3V regulator

and a 5V regulator. All systems on the Wi-FIRE board itself operate at 3.3V and are powered by the 3.3V regulator.

The 5V regulator is used to provide power for external circuits, such as shields, that require 5V for operation and to

supply USB 5.0V when the Wi-FIRE is used as a USB Host. The 5V regulator can be completely disabled if it is not

needed for a given application.