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@rdb
Last active October 1, 2023 16:10
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Access joysticks/game controllers from Python in Linux via the joystick driver. See https://discourse.panda3d.org/t/game-controllers-on-linux-without-pygame/14128
# Released by rdb under the Unlicense (unlicense.org)
# Based on information from:
# https://www.kernel.org/doc/Documentation/input/joystick-api.txt
import os, struct, array
from fcntl import ioctl
# Iterate over the joystick devices.
print('Available devices:')
for fn in os.listdir('/dev/input'):
if fn.startswith('js'):
print(' /dev/input/%s' % (fn))
# We'll store the states here.
axis_states = {}
button_states = {}
# These constants were borrowed from linux/input.h
axis_names = {
0x00 : 'x',
0x01 : 'y',
0x02 : 'z',
0x03 : 'rx',
0x04 : 'ry',
0x05 : 'rz',
0x06 : 'throttle',
0x07 : 'rudder',
0x08 : 'wheel',
0x09 : 'gas',
0x0a : 'brake',
0x10 : 'hat0x',
0x11 : 'hat0y',
0x12 : 'hat1x',
0x13 : 'hat1y',
0x14 : 'hat2x',
0x15 : 'hat2y',
0x16 : 'hat3x',
0x17 : 'hat3y',
0x18 : 'pressure',
0x19 : 'distance',
0x1a : 'tilt_x',
0x1b : 'tilt_y',
0x1c : 'tool_width',
0x20 : 'volume',
0x28 : 'misc',
}
button_names = {
0x120 : 'trigger',
0x121 : 'thumb',
0x122 : 'thumb2',
0x123 : 'top',
0x124 : 'top2',
0x125 : 'pinkie',
0x126 : 'base',
0x127 : 'base2',
0x128 : 'base3',
0x129 : 'base4',
0x12a : 'base5',
0x12b : 'base6',
0x12f : 'dead',
0x130 : 'a',
0x131 : 'b',
0x132 : 'c',
0x133 : 'x',
0x134 : 'y',
0x135 : 'z',
0x136 : 'tl',
0x137 : 'tr',
0x138 : 'tl2',
0x139 : 'tr2',
0x13a : 'select',
0x13b : 'start',
0x13c : 'mode',
0x13d : 'thumbl',
0x13e : 'thumbr',
0x220 : 'dpad_up',
0x221 : 'dpad_down',
0x222 : 'dpad_left',
0x223 : 'dpad_right',
# XBox 360 controller uses these codes.
0x2c0 : 'dpad_left',
0x2c1 : 'dpad_right',
0x2c2 : 'dpad_up',
0x2c3 : 'dpad_down',
}
axis_map = []
button_map = []
# Open the joystick device.
fn = '/dev/input/js0'
print('Opening %s...' % fn)
jsdev = open(fn, 'rb')
# Get the device name.
#buf = bytearray(63)
buf = array.array('B', [0] * 64)
ioctl(jsdev, 0x80006a13 + (0x10000 * len(buf)), buf) # JSIOCGNAME(len)
js_name = buf.tobytes().rstrip(b'\x00').decode('utf-8')
print('Device name: %s' % js_name)
# Get number of axes and buttons.
buf = array.array('B', [0])
ioctl(jsdev, 0x80016a11, buf) # JSIOCGAXES
num_axes = buf[0]
buf = array.array('B', [0])
ioctl(jsdev, 0x80016a12, buf) # JSIOCGBUTTONS
num_buttons = buf[0]
# Get the axis map.
buf = array.array('B', [0] * 0x40)
ioctl(jsdev, 0x80406a32, buf) # JSIOCGAXMAP
for axis in buf[:num_axes]:
axis_name = axis_names.get(axis, 'unknown(0x%02x)' % axis)
axis_map.append(axis_name)
axis_states[axis_name] = 0.0
# Get the button map.
buf = array.array('H', [0] * 200)
ioctl(jsdev, 0x80406a34, buf) # JSIOCGBTNMAP
for btn in buf[:num_buttons]:
btn_name = button_names.get(btn, 'unknown(0x%03x)' % btn)
button_map.append(btn_name)
button_states[btn_name] = 0
print('%d axes found: %s' % (num_axes, ', '.join(axis_map)))
print('%d buttons found: %s' % (num_buttons, ', '.join(button_map)))
# Main event loop
while True:
evbuf = jsdev.read(8)
if evbuf:
time, value, type, number = struct.unpack('IhBB', evbuf)
if type & 0x80:
print("(initial)", end="")
if type & 0x01:
button = button_map[number]
if button:
button_states[button] = value
if value:
print("%s pressed" % (button))
else:
print("%s released" % (button))
if type & 0x02:
axis = axis_map[number]
if axis:
fvalue = value / 32767.0
axis_states[axis] = fvalue
print("%s: %.3f" % (axis, fvalue))
@rdb
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rdb commented Nov 5, 2022

I checked and instead of os.open there may be an easier alternative, by calling this on the file after the open call:

os.set_blocking(jsdev.fileno(), False)

Of course you'll need to deal with the exception you will probably get when calling read() without data being available.

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