Pololu Wixel User manual

Pololu Wixel User's Guide
Pololu Wixel User's Guide © 2001–2011 Pololu Corporation
http://www.pololu.com/docs/0J46 Page 1 of 58

1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.a. Module Pinout and Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.b. Supported Operating Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.c. Government Regulations for Radio Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2. Contacting Pololu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3. Getting Started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.a. Installing Windows Drivers and Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.b. Installing Linux Drivers and Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.c. Installing Mac OS Drivers and Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.d. Loading an Example App . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4. Configuring Your Wixels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
5. Connecting Your Wixels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.a. Connecting Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5.b. Connecting a Microcontroller via TTL Serial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
5.c. Connecting Buttons and Starting the Bootloader . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
6. Using a Virtual COM Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
6.a. Determining the Port Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
6.b. Using a Terminal Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
6.c. Writing PC Software to Use a Serial Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
7. Ensuring a Good Radio Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
8. Schematic Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
9. Wixel Apps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
9.a. Example App: Blink LED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
9.b. Wireless Serial App . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
9.c. USB-to-Serial App . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
9.d. I/O Repeater App . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
9.e. ShiftBrite App . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
9.f. Wireless Tilt Mouse App . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
9.g. Serial-to-I²C App . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
10. Writing Your Own Wixel App . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
10.a. Getting Started in Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
10.b. Compiling an Example App . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
10.c. Using the Eclipse IDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
10.d. Sharing Your App with the Wixel Community . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
10.e. USB Configurations Recognized by the Wixel Configuration Software . . . . . . . . . . . . . . . 55
10.f. Wixel App File Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
11. The Wixel USB Bootloader . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Pololu Wixel User's Guide © 2001–2011 Pololu Corporation
Page 2 of 58

Wixel programmable USB
wireless module.
Wixel programmable USB
wireless module enabling
wireless communication
between a PC and robot.
1. Overview
The Pololu Wixel is a general-purpose programmable module featuring a
2.4 GHz radio and USB. The Wixel is based around the CC2511F32
[http://focus.ti.com/docs/prod/folders/print/cc2511f32.html] microcontroller from
Texas Instruments, which has an integrated radio transceiver, 32 KB of
flash memory, 4 KB of RAM, and a full-speed USB interface. A total of
15 general-purpose I/O lines are available, including 6 analog inputs, and
the 0.1" pin spacing makes the Wixel easy to use with breadboards
[http://www.pololu.com/catalog/category/28] and perfboards.
We provide free, open-source apps for the Wixel that you can load and
configure with its built-in USB bootloader, turning it into whatever you
need for your current project. Simply download a different app to reuse
the Wixel in your next project.
Our Wireless Serial app turns a pair of Wixels into a wireless USB/TTL
serial link for communication between two microcontrollers or between a
PC and a microcontroller. This can be used, for example, for
communication between two robots or to remotely monitor a robot from a
computer. A special version of this app is designed for use with our Wixel
shield for Arduino [http://www.pololu.com/catalog/product/2500], which
makes it easy to add wireless capabilities (including wireless
programmability) to an Arduino [http://www.pololu.com/catalog/product/1616]
or Arduino clone. Using an RF bit rate of 350 kbps, the serial app is
capable of transmitting or receiving up to 10 KB of data per second and
can reach a range of approximately 50 feet (under typical conditions
indoors). Multiple serial links can be used simultaneously on different
channels. Detailed information about the wireless serial app is available in Section 9.b.
Our USB-to-Serial app turns a single Wixel into a USB-to-TTL serial adapter that is capable of baud rates as
high as 350,000 bps and supports four serial control signals. This app does not use the radio. Detailed information
about this app is available in Section 9.c.
Our I/O Repeater app allows you to wirelessly extend the reach of your microcontroller’s I/O lines up to 50 feet
using two or more Wixels. Detailed information about this app is available in Section 9.d.
We plan to release additional apps in the future for wireless AVR programming, wireless sensing, and more.
You can also write your own apps using the open-source Wixel SDK (see Section 10) and share them with the
community.
Included Hardware
The Wixel is available in two versions:
The Partial Kit version [http://www.pololu.com/catalog/product/1337] comes with a 25×1 straight 0.1" male header
strip [http://www.pololu.com/catalog/product/965]. This version is ideal for compact installations and allows flexibility
in choice of connectors.
The Assembled version [http://www.pololu.com/catalog/product/1336] comes with its header pins soldered in, so it is
ready to be connected to your project with no soldering required.
Pololu Wixel User's Guide © 2001–2011 Pololu Corporation
1. Overview Page 3 of 58

Wixel programmable USB wireless
module (without header pins installed).
Wixel programmable USB wireless
module (fully assembled).
1.a. Module Pinout and Components
The Wixel can connect to a computer’s USB port via a USB A to mini-B cable [http://www.pololu.com/catalog/product/
130] (not included). The USB connection is used to configure the Wixel and also to transmit and receive data. The
USB connection can also provide power to the Wixel.
On the side of the board opposite the USB connector, the Wixel has a 2.4 GHz PCB trace antenna. This antenna,
along with the other RF circuitry, forms a radio that allows the Wixel to send and receive data packets in the
2.4 GHz band. The Wixel is based on the CC2511F32 microcontroller from Texas Instruments, which makes it
compatible with the CC2500 transceiver, the CC2510Fx family, and the CC2511Fx family of chips from Texas
Instruments. The Wixel’s radio is not compatible with Wi-Fi, Zigbee, or Bluetooth. The antenna is a “meandered
Inverted F” design that is described in Texas Instrument’s application note AN043 [http://focus.ti.com/lit/an/swra117d/
swra117d.pdf].
Pololu Wixel User's Guide © 2001–2011 Pololu Corporation
1. Overview Page 4 of 58

Wixel programmable USB wireless
module, bottom view with US
quarter for size reference.
The three GND pins are all connected and are at 0 V by definition.
When connecting the Wixel to other electronic systems, you should
make sure that the Wixel’s GND is connected to the other system’s
GND unless you are doing something very advanced.
The Wixel can be powered from VIN pin. Simply connect a 2.7–6.5 V
power source between VIN and GND, with the positive terminal going
to VIN. It is OK to connect VIN and USB at the same time. See Section
5.a for more information about powering your Wixels.
The VALT pin is connected to three things: the 5V USB bus power from
the USB port (through a diode), VIN (through a diode), and to the input
of the Wixel’s on-board 3.3 V regulator. The connection to 5V is
switched off when a power supply is connected to VIN. Most people
will not need to use the VALT pin: see Section 5.a for example uses.
The pin labeled 3V3 on the board (3.3V Output in the diagram above)
is connected to the output of the Wixel’s 3.3V regulator. This power
source can be used to power other low-current peripherals in your
system. With an input voltage of 5 V (either from USB, VIN, or VALT), this output can provide up to 150 mA of
current. At higher input voltages, this output can provide up to 100 mA.
The pin labeled RST on the board (RESET in the diagram above) is the reset line of the microcontroller. This pin
can be driven low to perform a hard reset of the Wixel’s microcontroller. This should not be necessary for typical
users, but it can be useful while you are developing a Wixel application (see Section 5.c). This pin is internally
pulled high to 3.3 V, so it is okay to leave it unconnected. If you do wire something to this pin, the CC2511F32
datasheet recommends adding an external RC filter with values of 1 nF and 2.7 kΩ close to the pin in order to
avoid unintended reset of the microcontroller.
The Wixel has 15 free I/O lines whose behavior depends on the application that is loaded onto the Wixel.
Specifically, these are all of the pins on Port 0 (P0_0 through P0_5), all of the pins on Port 1 (P1_0 through
P1_7), and P2_1. The P2_1 pin is tied to the red LED but the other 14 free I/O lines are only connected to the
microcontroller. The P2_2 line is also accessible, but it is tied to the yellow LED and is used to get the Wixel into
bootloader mode (see Section 5.c).
The amount of current that can be supplied by the CC2511F32’s I/O pins is not well-documented by the
manufacturer. According to this forum post by a TI Employee [http://e2e.ti.com/support/low_power_rf/f/155/p/31555/
319919.aspx], regular I/O pins are designed to be able to source 4 mA while P1_0 and P1_1 are designed for 20 mA.
Caution: The Wixel’s I/O lines are not 5V tolerant. You must use level-shifters, diodes, or voltage
dividers to connect the Wixel to outputs from 5V systems.
The CC2511F32 has several peripherals that are available to be used in Wixel applications:
• 2 USARTs which can perform asynchronous serial or SPI communication
• 3 timers that are capable of PWM output as shown above, plus 1 more internal timer
• 6 analog input-capable pins, connected to a 7–12 bit ADC
Pololu Wixel User's Guide © 2001–2011 Pololu Corporation
1. Overview Page 5 of 58

Wixel indicator LEDs.
Different Wixel applications may use different sets of these peripherals. Consult the application documentation
for details on the behavior of the I/O lines.
The pinout and peripheral diagram at the top of this section is also available as a printable pdf
[http://www.pololu.com/file/download/wixel_pinout.pdf?file_id=0J462] (145k pdf).
The Wixel has three indicator LEDs:
Green USB LED
The green LED is powered from USB, so it can only be turned
on when USB cable is connected and supplying power to the
Wixel.
While the Wixel is in bootloader mode (i.e. the app is stopped),
this LED is used to indicate the USB status of the device. When
the Wixel USB Bootloader connects to USB, the green LED
starts blinking slowly. The blinking continues until the
bootloader receives a particular message from the computer
indicating that the Wixel USB Bootloader drivers are installed
correctly (see Section 3.a for driver installation instructions).
After the bootloader gets this message, the green LED will do a
double-blinking pattern. The green LED also turns off during
USB Suspend Mode, which happens when the computer goes to
sleep or shuts down the USB port for any other reason.
While the Wixel is running its app, the behavior of the LED depends on the app. The standard apps provided by
Pololu all behave as follows: When the app connects to USB, the green LED starts blinking slowly. The blinking
continues until the app receives a particular message from the computer indicating that the app’s drivers are
installed correctly. After the app gets this message, the green LED turns solidly on. The green LED also turns off
during USB Suspend Mode, which happens when the computer goes to sleep or shuts down the USB port for any
other reason.
Red LED
While the Wixel is in bootloader mode (i.e. the app is stopped), this LED indicates whether there is an application
on the Wixel. If there is no application, the red LED will be on. Otherwise, it will be off. By default, the Wixel
does not have an application on it, so this LED will be on the first time you power your Wixel.
The P2_1 pin is connected to the red LED, so this line will go high when the red LED is on and otherwise be
pulled low.
While the Wixel is running its app, the behavior of this LED depends on the app. See the documentation of your
particular app for more details.
Yellow LED
While the Wixel is in bootloader mode (i.e. the app is stopped), this LED turns solidly on and flickers whenever
the bootloader receives a command from Wixel software on the computer. The Wixel Configuration Utility
queries the state of the bootloader once per second, so if the Wixel Configuration Utility is open then the LED
will flicker once per second. While the Wixel is being programmed, the yellow LED will constantly flicker.
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1. Overview Page 6 of 58

The P2_2 pin is connected to the yellow LED, so this line will go high when the yellow LED is on and otherwise
be pulled low.
While the Wixel is running its app, the behavior of this LED depends on the app. See the documentation of your
particular app for more details.
1.b. Supported Operating Systems
The Wixel USB drivers and configuration software currently work under Windows 7, Windows Vista,
Microsoft Windows XP (SP 3), and Linux. We plan to support Mac OS in the future.
Any Wixel app that implements a single USB virtual COM port will work on Linux or Mac OS with no special
driver installation required. Any Wixel app that implements a Human Interface Device (HID) will work on
Windows, Linux, or Mac OS with no special driver installation required. Therefore, you can use most Wixel Apps
with Mac OS but you will need a Windows or Linux computer to reconfigure the Wixel.
1.c. Government Regulations for Radio Devices
Warning about radio regulations: The Wixel has not been tested or certified for conformance with
any radio regulations, and the Wixel is shipped with only a bootloader that does not use the radio.
The 2.4 GHz band is relatively unrestricted in many parts of the world, but it is your responsibility to
comply with your local regulations if you program your Wixel to use its wireless capabilities.
The Wixel is a multi-purpose development platform, not a finished product, and it is not certified by the FCC
or any other government agency. It is your responsibility to follow local regulations and use good engineering
practices when developing, installing, and configuring apps for your Wixel. The Wixel has a low-power radio and
uses the reference PCB antenna suggested by TI, so we expect typical applications developed for the Wixel to
comply with FCC rules, but the Wixel is not intended for integration into other products. If you are contemplating
adding Wixel-like features to your product, we recommend that you integrate the CC2511 IC directly using
documentation from TI; any software developed for the Wixel should work on any other CC2511-based platform.
For more information on the requirements for operating a 2.4 GHz device, see TI Application Note 032:
SRD regulations for license-free transceiver operation in the 2.4 GHz band [http://focus.ti.com/lit/an/swra060/
swra060.pdf].
Pololu Wixel User's Guide © 2001–2011 Pololu Corporation
1. Overview Page 7 of 58

Wixel programmable USB
wireless module with USB cabled
connected.
2. Contacting Pololu
We would be delighted to hear from you about any of your projects and
about your experience with the Wixel. You can contact us
[http://www.pololu.com/contact] directly or post on our forum
[http://forum.pololu.com/]. Tell us what we did well, what we could improve,
what you would like to see in the future, or anything else you would like
to say!
Pololu Wixel User's Guide © 2001–2011 Pololu Corporation
2. Contacting Pololu Page 8 of 58

3. Getting Started
3.a. Installing Windows Drivers and Software
Before you connect a Wixel to a computer running Microsoft Windows, you should install the drivers:
1. Download the Wixel Windows Drivers and Software [http://www.pololu.com/file/download/wixel-
windows-110705.zip?file_id=0J448] (12MB zip)
2. Open the ZIP archive and run setup.exe. The installer will guide you through the steps required to install
the Wixel Configuration Utility, the Wixel command-line utility (WixelCmd), and the Wixel drivers on your
computer. If the installer fails when run directly from the ZIP file, extract the contents of the ZIP file to a
temporary directory on your computer, right click setup.exe, and select “Run as Administrator”.
3. During the installation, Windows will warn you that the drivers have not been tested by Microsoft and
recommend that you stop the installation. Click “Continue Anyway” (Windows XP) or “Install this driver
software anyway” (Windows 7 and Vista).
4. After the installation is finished, your start menu should have a shortcut to the Wixel Configuration Utility
(in the Pololu folder). This is a Windows application that allows you to load apps onto your Wixel. There
will also be a command-line utility called WixelCmd which you can run at a Command Prompt.
Windows 7 and Windows Vista users: Your computer should now automatically install the necessary drivers
when you connect a Wixel. No further action from you is required.
Windows XP users: Follow steps 5–9 for each new Wixel you connect to your computer. You will also have to
follow these steps again the first time you run an actual Wixel app on the Wixel.
5. Connect the device to your computer’s USB port.
6. When the “Found New Hardware Wizard” is displayed, select “No, not this time” and click “Next”.
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3. Getting Started Page 9 of 58

7. On the second screen of the “Found New Hardware Wizard”, select “Install the software automatically”
and click “Next”.
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8. Windows XP will warn you again that the driver has not been tested by Microsoft and recommend that
you stop the installation. Click “Continue Anyway”.
9. When you have finished the “Found New Hardware Wizard”, click “Finish”.
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3. Getting Started Page 11 of 58

After installing the drivers, if you go to your computer’s Device Manager and expand the “Pololu USB Devices”
list, you should see an entry for the Pololu Wixel USB Bootloader.
Windows Vista or Windows 7 Device
Manager showing a Wixel in bootloader
mode.
Windows XP Device Manager showing a
Wixel in bootloader mode.
If you see the “Pololu Wixel USB Bootloader” entry in your device manager, it means that your Wixel is in
bootloader mode. Your Wixel should go into bootloader mode when you first plug it into USB, because there is no
app on the Wixel by default. Once you have loaded an app onto the Wixel using the Wixel Configuration Utility,
and the app is running, then you will not see the Pololu Wixel USB Bootloader entry in your Device Manager.
The entry you see in the Device Manager will depend on the application that is loaded on the Wixel. Some apps
might not enable the USB interface, in which case you will see no entry for the Wixel in the Device Manager.
However, typical Wixel Apps will appear in your Device Manager as a single Virtual COM port (with product ID
0x2200) in the “Ports (COM & LPT)” list as shown below:
Pololu Wixel User's Guide © 2001–2011 Pololu Corporation
3. Getting Started Page 12 of 58

Windows Vista or Windows 7 Device
Manager showing a Wixel that is
running an app with a virtual COM port.
Windows XP Device Manager showing a
Wixel that is running an app with a
virtual COM port.
In parentheses, you will see the name of the port (for example, COM5 or COM6). Some software will not allow
connection to higher COM port numbers. If you need to change the COM port number assigned to a Wixel, you
can do so using the Device Manager. Bring up the properties dialog for the COM port and click the “Advanced…”
button in the “Port Settings” tab. From this dialog you can change the COM port assigned to your device.
Windows will remember which COM port was assigned to which Wixel using the built-in serial number of the
Wixel; a given Wixel will always get assigned to the same COM port regardless of which USB port it is plugged
into.
Pololu Wixel User's Guide © 2001–2011 Pololu Corporation
3. Getting Started Page 13 of 58

3.b. Installing Linux Drivers and Software
The Wixel Configuration Utility running in Ubuntu Linux.
You can download the Wixel Configuration Utility and the Wixel command-line utility (WixelCmd) for Linux
here:
•Wixel Linux Software for i386 (32-bit) [http://www.pololu.com/file/download/wixel-
linux-110623-i386.tar.gz?file_id=0J489] (211k gz)
•Wixel Linux Software for amd64 (64-bit) [http://www.pololu.com/file/download/wixel-
linux-110623-amd64.tar.gz?file_id=0J490] (216k gz)
Unzip the tar/gzip archive by running “tar -xzvf” followed by the name of the file. After following the instructions
in README.txt, you can run the programs by executing wixelconfig or wixelcmd.
Any Wixel app that implements a USB virtual COM port or a Human Interface Device (HID) will work on Linux
with no special driver installation required.
The virtual COM ports are managed by the cdc-acm kernel module, whose source code you can find in
your kernel’s source code in drivers/usb/class/cdc-acm.c. When you connect a Wixel running an app that
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3. Getting Started Page 14 of 58

implements a virtual serial port to the PC, the virtual serial port should appear as a device with a name like /dev/
ttyACM0 (the number depends on how many other ACM devices you have plugged in). You can use any terminal
program (such as kermit or screen) to send and receive bytes on those ports.
3.c. Installing Mac OS Drivers and Software
The Wixel software currently does not work on Mac OS, but certain Wixel apps should. See Section 1.b for
details.
3.d. Loading an Example App
When you first get your Wixel it will have no application loaded. To make your Wixel do something useful, you
must load an app onto it. This section guides you through the steps needed to load an example application onto
the Wixel using the Wixel Configuration Utility.
1. Install the Wixel drivers and software by following the instructions in the preceding sections.
2. Download the example application here: Example Blink LED App v1.0 [http://www.pololu.com/file/
download/example_blink_led_v1.0.wxl?file_id=0J449] (11k wxl). If you want to see the source code, it is in the Wixel
SDK under apps/example_blink_led. (See Section 10.a.)
3. Open the app in the Wixel Configuration Utility. To do this in Windows, you can simply double-click on
the Wixel App (WXL) file. Alternatively, you can open the Wixel Configuration Utility, click the “Open…”
button, and select the Wixel App file. In Windows, you can find the Wixel Configuration Utility in the Pololu
folder in your Start Menu.
4. Connect a Wixel to your computer via USB. You should see it appear in the “Wixels” list. If it does not
appear, you might need to use a button or wire to get your Wixel into bootloader mode (see Section 5.c). At
this point, your screen should look something like this:
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3. Getting Started Page 15 of 58

The Wixel Configuration Utility with the Example Blink LED App open.
5. Note that in the Wixels box, there is a list of all the Wixels connected to USB that the Wixel
Configuration Utility can recognize. There is one Wixel connected, and its 32-bit serial number is displayed
in the list. Also note that in the App Configuration box, we have opened the example_blink_led_v1.0.wxl
app. This app has one parameter, blink_period_ms, and it is currently set to 500 (the default).
6. Select the Wixel by left-clicking on its entry in the Wixels list. If you see a dialog box pop up, this
is because the Wixel already has an application on it and the Auto Read checkbox is checked. Click the
“Cancel” button in that dialog because we are not interested in reading the contents of the Wixel yet.
7. Click the Write to Wixel button. This writes the currently open app and the settings to the selected
Wixel, and then starts running the application.
8. The example blink LED application should be running now. The Wixel’s yellow LED should be off,
and the red LED should be blinking. If you are in Windows XP and this is the first time you have run an
application on this Wixel, the Found New Hardware Wizard will pop up and you will have to follow steps
5–9 from Section 3.a to install the drivers properly. After the USB drivers are installed properly, the green
LED should be on solid. Congratulations, you have successfully configured your Wixel!
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9. The speed of the blinking is determined by the blink_period_ms parameter. The units of this parameter
are milliseconds (ms). Try changing blink_period_ms to 100 by double-clicking on the number and typing
“100”. You can now write the new configuration to the Wixel by clicking the “Write to Wixel” button. After
the writing is done and the app is running, you should see the red LED blinking 5 times faster than it was
before.
10. The Wixel Configuration Utility can also read the settings from the Wixel. To demonstrate this, close
the Wixel Configuration Utility, reopen it, and select your Wixel. Since the Auto Read checkbox is checked
by default, and there is an application on the Wixel, the Wixel Configuration Utility will attempt to read the
Wixel’s settings. If you have not yet opened the correct app, a dialog box like the one below will pop up:
If Auto Read is enabled when you select a Wixel with an app on it, then you might be prompted
you to open the App File.
11. To read the settings from a Wixel, you will need to open the app that is currently on the Wixel. Click
the “Open” button in the dialog, and select example_blink_led_v1.0.wxl.
It is necessary to open the app file that you originally loaded onto the Wixel because the file
contains metadata required to interpret the settings contained in the Wixel’s flash memory. If
you open a different app file, even a different version of the same app, your settings will likely
be corrupted. In this case, a warning dialog box will pop up to warn you and give you some
options. Since you still have the correct app file, you should not see that dialog now.
12. After you open the Wixel App file, the Wixel Configuration Utility will read the Wixel and compare its
contents to what is in the app. You will then see the Wixel’s settings displayed on the right: blink_period_ms
should be 100. Note that the number 100 is displayed in bold. This is because it differs from the default
setting, which is 500. You can reset it to the default at any time by right-clicking on the number and selecting
“Reset to Default Value”.
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3. Getting Started Page 17 of 58

After completing this tutorial you should be comfortable with writing apps to the Wixel and reading back the
settings. This is all you need to know in order to configure your Wixels. When you load a real application, such
as the Wireless Serial App [http://www.pololu.com/docs/0J46/9.b], the only thing that will be different are the names
and meanings of the parameters. To understand what the different parameters mean, refer to the documentation
for your specific app.
Some apps might implement a non-standard USB interface (or no USB interface at all). In that case, they will
not be recognized by the Wixel Configuration Utility while the app is running, so you will need to get them into
bootloader mode manually (see Section 5.c and also the app’s documentation).
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3. Getting Started Page 18 of 58

4. Configuring Your Wixels
The Wixel Configuration Utility allows you to write and read settings from the Wixel. This section explains all of
the features of the Wixel Configuration Utility in detail.
The Wixel Configuration Utility with 2 Wixels connected and an App file open.
Wixels
On the left side of the window, in the Wixels box, you can see a list of all the Wixels connected to the computer
that are recognized by the Wixel Configuration Utility. The Wixel Configuration Utility should recognize any
Wixel that is in bootloader mode (i.e. the app is stopped) or is running an app that implements a single USB
Virtual COM port with a USB Vendor ID of 0x1FFB (for Pololu) and a Product ID of 0x2200. If your Wixel is
connected to your computer, but does not show up in the Wixel Configuration Utility, then your drivers might not
be installed properly, or the Wixel might be running an application that uses a different type of USB interface or
doesn’t use USB at all. If you have trouble getting the Wixel Configuration Utility to recognize your Wixel, then
see Section 10 for help.
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4. Configuring Your Wixels Page 19 of 58

The text displayed in the Wixel list (e.g. “07-C2-C8-3A”) is the serial number of your Wixel. Each Wixel has a
unique 32-bit serial number which was randomly generated and assigned to it when the Wixel was manufactured.
The icon displayed in the Wixel list represents the current state of the Wixel. Each Wixel will be in one of these
states:
Wixel Status Icon Description
App Running The app you loaded on the Wixel is now running.
App Stopped The app you loaded on the Wixel is currently stopped; the Wixel is in bootloader mode.
No App There is no app on the Wixel; the Wixel is in bootloader mode.
Reconnecting The Wixel is reconnecting, disconnecting, or in a transitional state.
If you select a Wixel, you can see more information about it in the area below the list. The USB Product ID is the
current product ID presented by the Wixel on its USB interface, as defined in the USB Specification. The Port
Name is the name of the virtual COM port that has been assigned to the Wixel. In Windows, the Port Name is
also available in the Device Manager.
The Stop App button stops the application that is running on the currently-selected Wixel, putting that Wixel into
bootloader mode. The Start App button takes the Wixel out of bootloader mode to run the application that is
currently on it.
App Configuration
On the right side of the window, in the App Configuration box, you can see the name of the currently-open app
and the current settings.
You can open a different app by clicking the “Open…” button. In Windows, you can also open an app simply by
double-clicking on it. The Wixel Configuration Utility can open app files in either the WXL format (documented
in 0J603) or the standard Intel HEX [http://en.wikipedia.org/wiki/Intel_HEX] format.
You can change the current settings by double-clicking on a value and typing a new value in. The parameters that
are available depend on the app that is open; different apps have different parameters available.
Please see the documentation for your specific application for an explanation of what the parameters
mean, and what the valid values are. The Wixel Configuration Utility will not prevent you from
entering invalid or inconsistent values.
Writing to a Wixel
After you have chosen the app and settings you want to use, and selected a Wixel, you can write the app and
settings to the Wixel by clicking the Write to Wixel button. This will erase whatever application was previously
on the Wixel and write the new application to the Wixel. When the write operation is done, the Wixel will be
restarted and the application should start running.
Reading from a Wixel
To read the settings from a Wixel that has been programmed, select the Wixel. If the Auto Read checkbox is
checked, then the Wixel will automatically be read. Uncheck this box if you want to retain current settings when
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4. Configuring Your Wixels Page 20 of 58