2024-02-17 01:14:46 +11:00

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Joystick :id=joystick

This feature provides game controller input as a joystick device supporting up to 6 axes and 32 buttons. Axes can be read either from an ADC-capable input pin, or can be virtual, so that its value is provided by your code.

An analog device such as a potentiometer found on an analog joystick's axes is based on a voltage divider, where adjusting the movable wiper controls the output voltage which can then be read by the microcontroller's ADC.

Usage :id=usage

Add the following to your rules.mk:

JOYSTICK_ENABLE = yes

By default the joystick driver is analog, but you can change this with:

JOYSTICK_DRIVER = digital

Configuration :id=configuration

By default, two axes and eight buttons are defined, with a reported resolution of 8 bits (-127 to +127). This can be changed in your config.h:

// Min 0, max 32
#define JOYSTICK_BUTTON_COUNT 16
// Min 0, max 6: X, Y, Z, Rx, Ry, Rz
#define JOYSTICK_AXIS_COUNT 3
// Min 8, max 16
#define JOYSTICK_AXIS_RESOLUTION 10

?> You must define at least one button or axis. Also note that the maximum ADC resolution of the supported AVR MCUs is 10-bit, and 12-bit for most STM32 MCUs.

Axes :id=axes

When defining axes for your joystick, you must provide a definition array typically in your keymap.c.

For instance, the below example configures two axes. The X axis is read from the A4 pin. With the default axis resolution of 8 bits, the range of values between 900 and 575 are scaled to -127 through 0, and values 575 to 285 are scaled to 0 through 127. The Y axis is configured as a virtual axis, and its value is not read from any pin. Instead, the user must update the axis value programmatically.

joystick_config_t joystick_axes[JOYSTICK_AXIS_COUNT] = {
    JOYSTICK_AXIS_IN(A4, 900, 575, 285),
    JOYSTICK_AXIS_VIRTUAL
};

Axes can be configured using one of the following macros:

JOYSTICK_AXIS_IN(input_pin, low, rest, high)
The ADC samples the provided pin. low, high and rest correspond to the minimum, maximum, and resting (or centered) analog values of the axis, respectively.
JOYSTICK_AXIS_VIRTUAL
No ADC reading is performed. The value should be provided by user code.

The low and high values can be swapped to effectively invert the axis.

Virtual Axes :id=virtual-axes

The following example adjusts two virtual axes (X and Y) based on keypad presses, with KC_P0 as a precision modifier:

joystick_config_t joystick_axes[JOYSTICK_AXIS_COUNT] = {
    JOYSTICK_AXIS_VIRTUAL, // x
    JOYSTICK_AXIS_VIRTUAL  // y
};

static bool precision = false;
static uint16_t precision_mod = 64;
static uint16_t axis_val = 127;

bool process_record_user(uint16_t keycode, keyrecord_t *record) {
    int16_t precision_val = axis_val;
    if (precision) {
        precision_val -= precision_mod;
    }

    switch (keycode) {
        case KC_P8:
            joystick_set_axis(1, record->event.pressed ? -precision_val : 0);
            return false;
        case KC_P2:
            joystick_set_axis(1, record->event.pressed ? precision_val : 0);
            return false;
        case KC_P4:
            joystick_set_axis(0, record->event.pressed ? -precision_val : 0);
            return false;
        case KC_P6:
            joystick_set_axis(0, record->event.pressed ? precision_val : 0);
            return false;
        case KC_P0:
            precision = record->event.pressed;
            return false;
    }
    return true;
}

Keycodes :id=keycodes

Key	Aliases	Description
`QK_JOYSTICK_BUTTON_0`	`JS_0`	Button 0
`QK_JOYSTICK_BUTTON_1`	`JS_1`	Button 1
`QK_JOYSTICK_BUTTON_2`	`JS_2`	Button 2
`QK_JOYSTICK_BUTTON_3`	`JS_3`	Button 3
`QK_JOYSTICK_BUTTON_4`	`JS_4`	Button 4
`QK_JOYSTICK_BUTTON_5`	`JS_5`	Button 5
`QK_JOYSTICK_BUTTON_6`	`JS_6`	Button 6
`QK_JOYSTICK_BUTTON_7`	`JS_7`	Button 7
`QK_JOYSTICK_BUTTON_8`	`JS_8`	Button 8
`QK_JOYSTICK_BUTTON_9`	`JS_9`	Button 9
`QK_JOYSTICK_BUTTON_10`	`JS_10`	Button 10
`QK_JOYSTICK_BUTTON_11`	`JS_11`	Button 11
`QK_JOYSTICK_BUTTON_12`	`JS_12`	Button 12
`QK_JOYSTICK_BUTTON_13`	`JS_13`	Button 13
`QK_JOYSTICK_BUTTON_14`	`JS_14`	Button 14
`QK_JOYSTICK_BUTTON_15`	`JS_15`	Button 15
`QK_JOYSTICK_BUTTON_16`	`JS_16`	Button 16
`QK_JOYSTICK_BUTTON_17`	`JS_17`	Button 17
`QK_JOYSTICK_BUTTON_18`	`JS_18`	Button 18
`QK_JOYSTICK_BUTTON_19`	`JS_19`	Button 19
`QK_JOYSTICK_BUTTON_20`	`JS_20`	Button 20
`QK_JOYSTICK_BUTTON_21`	`JS_21`	Button 21
`QK_JOYSTICK_BUTTON_22`	`JS_22`	Button 22
`QK_JOYSTICK_BUTTON_23`	`JS_23`	Button 23
`QK_JOYSTICK_BUTTON_24`	`JS_24`	Button 24
`QK_JOYSTICK_BUTTON_25`	`JS_25`	Button 25
`QK_JOYSTICK_BUTTON_26`	`JS_26`	Button 26
`QK_JOYSTICK_BUTTON_27`	`JS_27`	Button 27
`QK_JOYSTICK_BUTTON_28`	`JS_28`	Button 28
`QK_JOYSTICK_BUTTON_29`	`JS_29`	Button 29
`QK_JOYSTICK_BUTTON_30`	`JS_30`	Button 30
`QK_JOYSTICK_BUTTON_31`	`JS_31`	Button 31

API :id=api

`struct joystick_t` :id=api-joystick-t

Contains the state of the joystick.

Members :id=api-joystick-t-members

uint8_t buttons[]
A bit-packed array containing the joystick button states. The size is calculated as (JOYSTICK_BUTTON_COUNT - 1) / 8 + 1.
int16_t axes[]
An array of analog values for each defined axis.
bool dirty
Whether the current state needs to be sent to the host.

`struct joystick_config_t` :id=api-joystick-config-t

Describes a single axis.

Members :id=api-joystick-config-t-members

pin_t input_pin
The pin to read the analog value from, or JS_VIRTUAL_AXIS.
uint16_t min_digit
The minimum analog value.
uint16_t mid_digit
The resting or midpoint analog value.
uint16_t max_digit
The maximum analog value.

`void joystick_flush(void)` :id=api-joystick-flush

Send the joystick report to the host, if it has been marked as dirty.

`void register_joystick_button(uint8_t button)` :id=api-register-joystick-button

Set the state of a button, and flush the report.

Arguments :id=api-register-joystick-button-arguments

uint8_t button
The index of the button to press, from 0 to 31.

`void unregister_joystick_button(uint8_t button)` :id=api-unregister-joystick-button

Reset the state of a button, and flush the report.

Arguments :id=api-unregister-joystick-button-arguments

uint8_t button
The index of the button to release, from 0 to 31.

`int16_t joystick_read_axis(uint8_t axis)` :id=api-joystick-read-axis

Sample and process the analog value of the given axis.

Arguments :id=api-joystick-read-axis-arguments

uint8_t axis
The axis to read.

Return Value :id=api-joystick-read-axis-return

A signed 16-bit integer, where 0 is the resting or mid point.

`void joystick_set_axis(uint8_t axis, int16_t value)` :id=api-joystick-set-axis

Set the value of the given axis.

Arguments :id=api-joystick-set-axis-arguments

uint8_t axis
The axis to set the value of.
int16_t value
The value to set.

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