qmk-firmware/docs/feature_mouse_keys.md

Mousekeys

Mousekeys is a feature that allows you to emulate a mouse using your keyboard. You can move the pointer around, click up to 5 buttons, and even scroll in all 4 directions. QMK uses the same algorithm as the X Window System MouseKeysAccel feature. You can read more about it on Wikipedia.

Adding Mousekeys to a Keymap

There are two steps to adding Mousekeys support to your keyboard. You must enable support in the Makefile and you must map mouse actions to keys on your keyboard.

Adding Mousekeys Support in the Makefile

To add support for Mousekeys you simply need to add a single line to your keymap's Makefile:

MOUSEKEY_ENABLE = yes

You can see an example here: https://github.com/qmk/qmk_firmware/blob/master/keyboards/clueboard/keymaps/mouse_keys/Makefile

Mapping Mouse Actions to Keyboard Keys

You can use these keycodes within your keymap to map button presses to mouse actions:

Key	Aliases	Description
KC_MS_UP	KC_MS_U	Mouse Cursor Up
KC_MS_DOWN	KC_MS_D	Mouse Cursor Down
KC_MS_LEFT	KC_MS_L	Mouse Cursor Left
KC_MS_RIGHT	KC_MS_R	Mouse Cursor Right
KC_MS_BTN1	KC_BTN1	Mouse Button 1
KC_MS_BTN2	KC_BTN2	Mouse Button 2
KC_MS_BTN3	KC_BTN3	Mouse Button 3
KC_MS_BTN4	KC_BTN4	Mouse Button 4
KC_MS_BTN5	KC_BTN5	Mouse Button 5
KC_MS_WH_UP	KC_WH_U	Mouse Wheel Up
KC_MS_WH_DOWN	KC_WH_D	Mouse Wheel Down
KC_MS_WH_LEFT	KC_WH_L	Mouse Wheel Left
KC_MS_WH_RIGHT	KC_WH_R	Mouse Wheel Right
KC_MS_ACCEL0	KC_ACL0	Set mouse acceleration to 0
KC_MS_ACCEL1	KC_ACL1	Set mouse acceleration to 1
KC_MS_ACCEL2	KC_ACL2	Set mouse acceleration to 2

You can see an example in the _ML here: https://github.com/qmk/qmk_firmware/blob/master/keyboards/clueboard/keymaps/mouse_keys/keymap.c#L46

Configuring the Behavior of Mousekeys

The default speed for controlling the mouse with the keyboard is intentionally slow. You can adjust these parameters by adding these settings to your keymap's config.h file. All times are specified in milliseconds (ms).

#define MOUSEKEY_DELAY             300
#define MOUSEKEY_INTERVAL          50
#define MOUSEKEY_MAX_SPEED         10
#define MOUSEKEY_TIME_TO_MAX       20
#define MOUSEKEY_WHEEL_MAX_SPEED   8
#define MOUSEKEY_WHEEL_TIME_TO_MAX 40

MOUSEKEY_DELAY

When one of the mouse movement buttons is pressed this setting is used to define the delay between that button press and the mouse cursor moving. Some people find that small movements are impossible if this setting is too low, while settings that are too high feel sluggish.

MOUSEKEY_INTERVAL

When a movement key is held down this specifies how long to wait between each movement report. Lower settings will translate into an effectively higher mouse speed.

MOUSEKEY_MAX_SPEED

As a movement key is held down the speed of the mouse cursor will increase until it reaches MOUSEKEY_MAX_SPEED.

MOUSEKEY_TIME_TO_MAX

How long you want to hold down a movement key for until MOUSEKEY_MAX_SPEED is reached. This controls how quickly your cursor will accelerate.

MOUSEKEY_WHEEL_MAX_SPEED

The top speed for scrolling movements.

MOUSEKEY_WHEEL_TIME_TO_MAX

How long you want to hold down a scroll key for until MOUSEKEY_WHEEL_MAX_SPEED is reached. This controls how quickly your scrolling will accelerate.