Parameters, Versions – Pololu Wixel User Manual
Page 48
the app to a Wixel. (See
for more information on how this is done.) The Wixel should now appear to your
computer as a Human Interface Device.
If you are using Windows, there should be a new entry called “HID-compliant game controller” in your Device
Manager in the “Human Interface Devices” section. The Wixel will also show up as a keyboard and a mouse, but it
does not use those interfaces. To test the joystick functions, you can use the Game Controllers applet in the Control
Panel, where you should see a “Wixel Joystick” entry. Selecting this entry and clicking the Properties button will
display a dialog that shows the state of the joystick’s axes and buttons.
On Linux, the joystick should be represented by a new device node with a name like
/dev/input/js0
. You can test
the joystick with a program such as
jstest
or
jstest-gtk
.
The Wixel Configuration Utility does not detect Wixels with USB HID interfaces. Therefore, if you
need to reconfigure your 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).
This app’s parameters (detailed below) are used to configure how the Wixel’s inputs map to joystick functions. By
default, the six analog inputs P0_0 through P0_5 are mapped to six analog joystick axes, and the six digital inputs
P1_2 through P1_7 are mapped to six joystick buttons. Pull-ups are enabled for the buttons, which are configured as
inverted inputs (so the Wixel interprets a logic low as a button press). If you don’t need all of the joystick axes, some
or all of them can be disabled and the analog pins can be used as digital inputs for additional buttons instead.
Parameters
• buttonB_pin: The digital input pin that represents a joystick button; for example, a value of 12 selects the
P1_2 pin. A value of -1 disables the button.
• buttonB_invert: Set to 0 for a non-inverted input: a logic high on the pin indicates a button press. Set to 1
for an inverted input: a logic low on the pin indicates a button press. The default is 1 (inverted).
• axis_channel: The analog input (ADC channel) that represents a joystick axis. A value of -1 disables the axis.
• axis_invert: Set to 0 for a non-inverted axis: the axis position is proportional to the input voltage. Set to 1 for
an inverted axis: the axis position is inversely proportional to the input voltage. The default is 0 (non-inverted).
• PM_N_pull_enable: Enables (1) or disables (0) the internal pull-up or pull-down resistor on the
corresponding pin. (Note that P1_0 and P1_1 do not have pull-ups/pull-downs.) The direction the pin is pulled
is determined by the portM_pull_type parameter for Port M. The default is 0 (disabled) for Port 0, to avoid
interfering with analog readings, and 1 (enabled) for Port 1.
• portM_pull_type: Determines whether a pin on Port M is pulled down (0) or up (1) when the pin’s
PM_N_pull_enable parameter is set. The default is 1 (high).
Versions
•
(33k wxl), released
2013-08-12: Initial release.
Pololu Wixel User's Guide
© 2001–2014 Pololu Corporation
9. Wixel Apps
Page 48 of 64