Joy-Con Python Library

A Linux-based Python library for reading and decoding button information from Nintendo Joy-Con controllers using the evdev interface.

Note: This library currently only supports Linux. Windows and macOS support would require implementing HID or other platform-specific backends.

Features

• Linux Support - Works on Linux with the evdev interface
• Evdev Backend - Direct communication with Joy-Con controllers via Linux input subsystem
• Real-time Input - Read button states and analog sticks in real-time
• Multiple Controllers - Support for left, right, and Pro controllers
• Dual Joy-Con Mode - Use two Joy-Cons as a single controller
• Event System - Register callbacks for button press/release events
• Polling Mode - Continuous input monitoring at configurable rates
• Clean API - Simple, intuitive interface with Google-style docstrings
• Low Latency - Optimized for minimal input lag with device grabbing and efficient event reading

Requirements

• Python 3.10 or higher
• Linux operating system
• Bluetooth-connected Joy-Con controllers
• Dependencies installed automatically:
  • evdev (Linux event device interface)

Installation

pip install joycon-lib

Prerequisites - Bluetooth Setup

Linux Setup

Before using the library, you need to set up your Linux system:

1. Enable the hid_nintendo kernel driver (REQUIRED):

# Load the driver - this is required for Joy-Con support
sudo modprobe hid_nintendo

# To load automatically on boot (recommended):
echo "hid_nintendo" | sudo tee /etc/modules-load.d/hid_nintendo.conf

Note: Without the hid_nintendo driver, Joy-Con controllers won't be recognized as input devices.

2. Add udev rules for non-root access (RECOMMENDED):

Without these rules, you'll need to run your Python scripts with sudo.

# Create udev rules file
sudo tee /etc/udev/rules.d/50-joycon.rules << 'EOF'
# Nintendo Joy-Con (L/R) and Pro Controller
KERNEL=="event*", ATTRS{name}=="*Joy-Con*", MODE="0666"
KERNEL=="event*", ATTRS{name}=="*Pro Controller*", MODE="0666"
EOF

# Reload and apply rules
sudo udevadm control --reload-rules
sudo udevadm trigger

3. Connect Joy-Con via Bluetooth:

# Open Bluetooth control
bluetoothctl

# In bluetoothctl:
power on
agent on
default-agent
scan on

# Press sync button on Joy-Con (small button between SL/SR)
# Wait for Joy-Con to appear, note the MAC address

pair XX:XX:XX:XX:XX:XX
trust XX:XX:XX:XX:XX:XX
connect XX:XX:XX:XX:XX:XX

# Exit bluetoothctl
exit

Or you can use the GUI to connect to the Joy-Con device via Bluetooth.

Quick Start

Basic Usage

from joycon_lib import JoyCon, Button
import time

# Create and connect to Joy-Con
joycon = JoyCon(use_backend='evdev')  # Linux only
joycon.connect()  # Auto-finds first available Joy-Con

# Read button states
while True:
    buttons = joycon.read_buttons()
    if buttons.is_pressed(Button.A):
        print("A button pressed!")
    time.sleep(0.016)  # ~60 FPS

# Disconnect when done
joycon.disconnect()

Dual Joy-Con Mode

from joycon_lib import DualJoyCon, Button
import time

# Create dual Joy-Con controller
dual = DualJoyCon(use_backend='evdev')  # Linux only
dual.connect(auto_find=True)  # Auto-finds and connects both Joy-Cons

# Start polling
dual.start_polling(rate=60)

# Read from both controllers as one
while True:
    buttons = dual.get_button_state()  # Combined buttons from both
    left_stick, right_stick = dual.get_sticks()  # Both analog sticks
    
    if buttons.is_pressed(Button.A):
        print("A pressed!")
    if buttons.is_pressed(Button.L) and buttons.is_pressed(Button.R):
        print("L+R combo!")
    
    time.sleep(0.016)

dual.disconnect()

Running Examples

Quick Test

# Run the library's built-in test
python -m joycon_lib

Example Scripts

The examples/ directory contains various demonstration scripts:

Script	Description
example_stick.py	Test analog stick input
example_dual.py	Use both Joy-Cons independently
example_evdev.py	Test evdev backend (Linux only)

cd examples/
python example_dual.py  # Start with the interactive demo

API Reference

Core Classes

JoyCon

Main interface for single Joy-Con interaction.

Methods:

• connect(device_path=None, device_type=None) - Connect to a Joy-Con (evdev backend)
• disconnect() - Disconnect from the Joy-Con
• read_buttons() - Read current button state from device
• get_button_state() - Get current button state without reading
• get_left_stick() - Get left analog stick state
• get_right_stick() - Get right analog stick state
• start_polling(rate=60) - Start continuous polling
• stop_polling() - Stop polling
• register_callback(event_type, callback) - Register event callback
• list_devices() - List all available Joy-Con devices
• get_device_info() - Get information about connected device

DualJoyCon

Manages two Joy-Cons as a single controller.

Methods:

• connect(auto_find=True, left_path=None, right_path=None) - Connect to both Joy-Cons
• disconnect() - Disconnect both controllers
• read_input() - Read input from both Joy-Cons and combine
• get_button_state() - Get combined button state without reading
• get_left_stick() - Get left analog stick position
• get_right_stick() - Get right analog stick position
• get_sticks() - Get both analog stick positions as tuple
• start_polling(rate=60) - Start polling both controllers
• stop_polling() - Stop polling
• is_connected() - Check connection status of both Joy-Cons

ButtonState

Represents the current state of all buttons.

Methods:

• is_pressed(button) - Check if button is currently pressed
• is_released(button) - Check if button is currently released
• just_pressed(button) - Check if button was just pressed this frame
• just_released(button) - Check if button was just released this frame
• get_pressed_names() - Get list of pressed button names
• to_dict() - Convert button state to dictionary

Button Mappings

Controller	Buttons
Right Joy-Con	Y, X, B, A, SR_RIGHT, SL_RIGHT, R, ZR, PLUS, R_STICK, HOME
Left Joy-Con	UP, DOWN, LEFT, RIGHT, SR_LEFT, SL_LEFT, L, ZL, MINUS, L_STICK, CAPTURE
Pro Controller	All of the above

StickState

Represents analog stick position and provides utility methods.

Methods:

• get_angle() - Get stick angle in degrees (0-360)
• get_magnitude() - Get displacement from center (0.0-1.0)
• is_centered(deadzone=0.1) - Check if stick is centered
• get_direction_4way() - Get 4-way directional input
• get_direction_8way() - Get 8-way directional input

Attributes:

• x - X-axis value (-1.0 to 1.0)
• y - Y-axis value (-1.0 to 1.0)
• raw_x - Raw X value from controller
• raw_y - Raw Y value from controller

Troubleshooting

Common Issues

Joy-Con not detected:

• Ensure Joy-Con is paired via Bluetooth
• Check battery level
• Try re-pairing the controller
• On Linux, verify udev rules are installed

Permission denied errors (Linux):

• Add udev rules as shown in setup
• Run with sudo (not recommended)
• Ensure hid_nintendo kernel module is loaded

Connection drops:

• Keep Joy-Con within Bluetooth range
• Check for interference from other devices
• Ensure Joy-Con firmware is up to date

License

MIT License - See LICENSE file for details