Assembly, Parameters – Pololu Wixel User Manual
Page 50
Configuration Utility easily get the transmitter Wixel into bootloader mode when the transmitter Wixel is connected
to the computer via USB.
Download the
(15k wxl). Open it with the Wixel Configuration Utility, choose your settings, and write it to the
receiver Wixel. The receiver Wixel should now appear to your computer as a Human Interface Device. If you are
using Windows there should be a new entry entitled “HID-compliant mouse” in your Device Manager in the “Mice
and other pointing devices” section. The receiver will also show up as a keyboard, but it does not use that interface.
The Wixel Configuration Utility does not detect Wixels with USB HID interfaces. Therefore, if you
need to reconfigure your receiver Wixel, you will need to manually get it into bootloader mode (set
pin P2_2 high and reset – although this app monitors P2_2 all the time and enters the bootloader if it
goes high, so the reset is not strictly necessary).
Assembly
With the battery pack switched off, connect power for the transmitter Wixel. The black wire from the battery pack
should connect to a GND pin on the Wixel. The red wire from the battery pack should connect to VIN. To test the
connection, turn on the battery pack: the transmitter Wixel’s yellow LED should turn on. Remember to turn off the
battery pack while you are making connections.
Connect the GND of the Wixel to the GND (ground) pin of the accelerometer. Connect power for the accelerometer.
The MMA7361L accelerometer we used can run off of 3.3 V and draws relatively little current, so we powered it
from the Wixel’s 3V3 line by connecting 3V3 to the accelerometer’s VDD.
Make any connections necessary to enable your accelerometer. For the MMA7361L, we connected SLP to VDD.
Choose which axis of the accelerometer will control the mouse cursor’s horizontal movement and connect its output
to the transmitter Wixel’s P0_2 pin. If your accelerometer is oriented as shown in the picture above, you should use
the Y axis.
Choose which axis of the accelerometer will control the mouse cursor’s vertical movement and connect its output to
the transmitter Wixel’s P0_1 pin. If your accelerometer is oriented as shown in the picture above, you should use the
X axis.
Connect a normally-open (NO) pushbutton between the transmitter Wixel’s P1_2 pin and GND. This will be the left
mouse button. The P1_2 input line has an internal pull-up resistor, so the voltage on that line should be high (3.3 V)
when the button is not pressed. When the button is pressed, the voltage should go low (0 V).
In the same manner, connect a pushbutton between the transmitter Wixel’s P1_7 pin and GND. This will be the right
mouse button.
Parameters
Both the transmitter and receiver app have a parameter called radio_channel. The channel number is from 0 to 255
and determines which frequency to broadcast on. The default is 128. The transmitter and receiver must be on the same
channel to talk to each other. To avoid interference, Wixels that aren’t supposed to talk to each other should be at least
2 channels away from each other. For example, you could have one pair of Wixels on channel 128 and another pair
on 130.
The transmitter app has additional parameters to configure the behavior of the mouse:
Pololu Wixel User's Guide
© 2001–2014 Pololu Corporation
9. Wixel Apps
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