upkie::cpp::sensors::Joystick Class Reference

Sensor for a joystick controller. More...

#include <Joystick.h>

Public Member Functions
	Joystick (const std::string &device_path="/dev/input/js0")
	Open the device file. More...
	~Joystick () override
	Close device file.
bool	present () const noexcept
	Check if the device file was opened successfully.
std::string	prefix () const noexcept final
	Prefix of output in the observation dictionary. More...
void	write (Dictionary &output) final
	Write output to a dictionary. More...
Public Member Functions inherited from upkie::cpp::sensors::Sensor
virtual	~Sensor ()
	Destructor is virtual to deallocate lists of observers properly.
virtual std::string	prefix () const noexcept
	Prefix of output in the observation dictionary. More...
virtual void	write (Dictionary &observation)
	Write output to a dictionary. More...

Detailed Description

Sensor for a joystick controller.

Note

This sensor only works on Linux.

Axes are the same for PS4 and Xbox controllers, but buttons differ slightly.

Outputs

This sensor has the following outputs:

Buttons

Key	Type	Description
cross_button	float	bottom button (cross on PS4, A on Xbox)
square_button	float	left button (square on PS4, Y on Xbox)
triangle_button	float	top button (triangle on PS4, X on Xbox)
left_button	float	L1 on PS4, L on Xbox
right_button	float	R1 on PS4, R on Xbox

Note that the red button (circle on PS4, B on Xbox) serves as emergency stop 🚨: when it is pressed, the spine will terminate.

Continus axes

Key	Type	Description
left_axis	[float, float]	left analog joystick
right_axis	[float, float]	right analog joystick
left_trigger	float	left trigger if there is one (L2 on PS4)
right_trigger	float	right trigger if there is one (R2 on PS4)

Discrete axes

Key	Type	Description
pad_axis	[float, float]	directional pad

Constructor & Destructor Documentation

Joystick()

upkie::cpp::sensors::Joystick::Joystick

(

const std::string &

device_path = "/dev/input/js0"

)

Open the device file.

Parameters

[in]

device_path

Path to the joystick device file.

Member Function Documentation

prefix()

std::string upkie::cpp::sensors::Joystick::prefix ( ) const

inlinefinalvirtualnoexcept

Prefix of output in the observation dictionary.

Reimplemented from upkie::cpp::sensors::Sensor.

write()

void upkie::cpp::sensors::Joystick::write ( Dictionary &  output )

finalvirtual

Write output to a dictionary.

Parameters

[out]

output

Dictionary to write observations to.

Reimplemented from upkie::cpp::sensors::Sensor.

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The documentation for this class was generated from the following files:

• upkie/cpp/sensors/Joystick.h
• upkie/cpp/sensors/Joystick.cpp