Joysticks

Joystick drivers for Julia, tested on Linux and Windows, should also work on Mac.

Installation

using Pkg
pkg"add https://github.com/ufechner7/Joysticks.jl"

High level interface for reading the axes

using Joysticks

const js       = open_joystick()
const jsaxes   = JSState()

async_read!(js, jsaxes)

while true
    println(jsaxes)
    sleep(0.05)
end

After you called the function async_read! the struct jsaxes will be updated every few milli-seconds and will automatically reflect the state of the (max) 6 axis.

The values are of type Float64 in the range of -1.00 to 1.00.

The members of the struct are x, y, z and u, v, w.

High level interface reacting on button events

using Joysticks, Observables

const js        = open_joystick()
const jsbuttons = JSButtonState()

async_read!(js, nothing, jsbuttons)

on(jsbuttons.btn1) do val
    if val println("Button 1 pressed!") end
end
on(jsbuttons.btn2) do val
    if ! val println("Button 2 released!") end
end

The struct jsbuttons contains 12 observables, one for each possible button. Using the function on can be used to bind an action to a change of the button state. When pressed val is true, when released val is false.

The function async_read! must be called once to start the event loop for processing button events.

Reading both axes and buttons

using Joysticks, Observables

const js        = open_joystick()
const jsaxes    = JSState()
const jsbuttons = JSButtonState()

async_read!(js, jsaxes, jsbuttons)

The function async_read! must be called once to start the event loop for processing button events.

You can then access the axes values and assign events to buttons as in the examples above.

Using the second Joystick

Windows and Mac

using Joysticks, Observables
const js        = open_joystick("", JOYSTICK_2)

The counting starts at one.

Linux

using Joysticks, Observables
const js        = open_joystick("/dev/input/js1")

The counting starts at zero.

Reference

Constants

JS_EVENT_BUTTON, JS_EVENT_AXIS, JS_EVENT_INIT

Types

JSEvent, JSEvents, JSAxisState, JSButtonState, JSState

Functions

open_joystick(filename = "/dev/input/js0", device=JOYSTICK_1; glfw=false)
read_event(js::JSDevice)
axis_state!(axes::JSAxisState, event::JSEvent)
axis_state!(axes::JSState, event::JSEvent)
async_read!(js::JSDevice, jsaxes=nothing, jsbuttons=nothing)

Example of using the low-level interface (Linux only)

using Joystick

jsd = open_joystick()
axis_count   = jsd.axis_count
button_count = jsd.button_count
println(axis_count, " ", button_count)

Example for printing all events:

using Joystick

const jsdevice = open_joystick()
const jsaxes   = JSAxisState()

while (true)
    event = read_event(jsdevice)
    if ! isnothing(event) 
        if event.type == Int(JS_EVENT_BUTTON)
            println("Button ", event.number, " ", event.value != 0 ? "pressed" : "released")
        elseif event.type == Int(JS_EVENT_AXIS)
            axis = axis_state!(jsaxes, event)
            if axis <= 6
                println("axis: ", axis)
                println(jsaxes)
            end
        end
    end
    sleep(0.001)
end

Remark

The word axes is the plural of axis.