Mouse Keys
Mouse keys is a feature that allows you to emulate a mouse using your keyboard. You can move the pointer at different speeds, press 5 buttons and scroll in 8 directions.

Adding mouse keys to your keyboard

To use mouse keys, you must at least enable mouse keys support and map mouse actions to keys on your keyboard.

Enabling mouse keys

To enable mouse keys, add the following line to your keymap’s rules.mk:
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MOUSEKEY_ENABLE = yes
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Mapping mouse actions

In your keymap you can use the following keycodes to map key presses to mouse actions:
Key
Aliases
Description
KC_MS_UP
KC_MS_U
Move cursor up
KC_MS_DOWN
KC_MS_D
Move cursor down
KC_MS_LEFT
KC_MS_L
Move cursor left
KC_MS_RIGHT
KC_MS_R
Move cursor right
KC_MS_BTN1
KC_BTN1
Press button 1
KC_MS_BTN2
KC_BTN2
Press button 2
KC_MS_BTN3
KC_BTN3
Press button 3
KC_MS_BTN4
KC_BTN4
Press button 4
KC_MS_BTN5
KC_BTN5
Press button 5
KC_MS_BTN6
KC_BTN6
Press button 6
KC_MS_BTN7
KC_BTN7
Press button 7
KC_MS_BTN8
KC_BTN8
Press button 8
KC_MS_WH_UP
KC_WH_U
Move wheel up
KC_MS_WH_DOWN
KC_WH_D
Move wheel down
KC_MS_WH_LEFT
KC_WH_L
Move wheel left
KC_MS_WH_RIGHT
KC_WH_R
Move wheel right
KC_MS_ACCEL0
KC_ACL0
Set speed to 0
KC_MS_ACCEL1
KC_ACL1
Set speed to 1
KC_MS_ACCEL2
KC_ACL2
Set speed to 2

Configuring mouse keys

Mouse keys supports three different modes to move the cursor:
  • Accelerated (default): Holding movement keys accelerates the cursor until it reaches its maximum speed.
  • Kinetic: Holding movement keys accelerates the cursor with its speed following a quadratic curve until it reaches its maximum speed.
  • Constant: Holding movement keys moves the cursor at constant speeds.
  • Combined: Holding movement keys accelerates the cursor until it reaches its maximum speed, but holding acceleration and movement keys simultaneously moves the cursor at constant speeds.
The same principle applies to scrolling.
Configuration options that are times, intervals or delays are given in milliseconds. Scroll speed is given as multiples of the default scroll step. For example, a scroll speed of 8 means that each scroll action covers 8 times the length of the default scroll step as defined by your operating system or application.

Accelerated mode

This is the default mode. You can adjust the cursor and scrolling acceleration using the following settings in your keymap’s config.h file:
Define
Default
Description
MOUSEKEY_DELAY
300
Delay between pressing a movement key and cursor movement
MOUSEKEY_INTERVAL
50
Time between cursor movements in milliseconds
MOUSEKEY_MOVE_DELTA
5
Step size
MOUSEKEY_MAX_SPEED
10
Maximum cursor speed at which acceleration stops
MOUSEKEY_TIME_TO_MAX
20
Time until maximum cursor speed is reached
MOUSEKEY_WHEEL_DELAY
300
Delay between pressing a wheel key and wheel movement
MOUSEKEY_WHEEL_INTERVAL
100
Time between wheel movements
MOUSEKEY_WHEEL_MAX_SPEED
8
Maximum number of scroll steps per scroll action
MOUSEKEY_WHEEL_TIME_TO_MAX
40
Time until maximum scroll speed is reached
Tips:
  • Setting MOUSEKEY_DELAY too low makes the cursor unresponsive. Setting it too high makes small movements difficult.
  • For smoother cursor movements, lower the value of MOUSEKEY_INTERVAL. If the refresh rate of your display is 60Hz, you could set it to 16 (1/60). As this raises the cursor speed significantly, you may want to lower MOUSEKEY_MAX_SPEED.
  • Setting MOUSEKEY_TIME_TO_MAX or MOUSEKEY_WHEEL_TIME_TO_MAX to 0 will disable acceleration for the cursor or scrolling respectively. This way you can make one of them constant while keeping the other accelerated, which is not possible in constant speed mode.
  • Setting MOUSEKEY_WHEEL_INTERVAL too low will make scrolling too fast. Setting it too high will make scrolling too slow when the wheel key is held down.
Cursor acceleration uses the same algorithm as the X Window System MouseKeysAccel feature. You can read more about it on Wikipedia.

Kinetic Mode

This is an extension of the accelerated mode. The kinetic mode uses a quadratic curve on the cursor speed which allows precise movements at the beginning and allows to cover large distances by increasing cursor speed quickly thereafter. You can adjust the cursor and scrolling acceleration using the following settings in your keymap’s config.h file:
Define
Default
Description
MK_KINETIC_SPEED
undefined
Enable kinetic mode
MOUSEKEY_DELAY
8
Delay between pressing a movement key and cursor movement
MOUSEKEY_INTERVAL
8
Time between cursor movements in milliseconds
MOUSEKEY_MOVE_DELTA
25
Step size for accelerating from initial to base speed
MOUSEKEY_INITIAL_SPEED
100
Initial speed of the cursor in pixel per second
MOUSEKEY_BASE_SPEED
1000
Maximum cursor speed at which acceleration stops
MOUSEKEY_DECELERATED_SPEED
400
Decelerated cursor speed
MOUSEKEY_ACCELERATED_SPEED
3000
Accelerated cursor speed
MOUSEKEY_WHEEL_INITIAL_MOVEMENTS
16
Initial number of movements of the mouse wheel
MOUSEKEY_WHEEL_BASE_MOVEMENTS
32
Maximum number of movements at which acceleration stops
MOUSEKEY_WHEEL_ACCELERATED_MOVEMENTS
48
Accelerated wheel movements
MOUSEKEY_WHEEL_DECELERATED_MOVEMENTS
8
Decelerated wheel movements
Tips:
  • The smoothness of the cursor movement depends on the MOUSEKEY_INTERVAL setting. The shorter the interval is set the smoother the movement will be. Setting the value too low makes the cursor unresponsive. Lower settings are possible if the micro processor is fast enough. For example: At an interval of 8 milliseconds, 125 movements per second will be initiated. With a base speed of 1000 each movement will move the cursor by 8 pixels.
  • Mouse wheel movements are implemented differently from cursor movements. While it's okay for the cursor to move multiple pixels at once for the mouse wheel this would lead to jerky movements. Instead, the mouse wheel operates at step size 1. Setting mouse wheel speed is done by adjusting the number of wheel movements per second.

Constant mode

In this mode you can define multiple different speeds for both the cursor and the mouse wheel. There is no acceleration. KC_ACL0, KC_ACL1 and KC_ACL2 change the cursor and scroll speed to their respective setting.
You can choose whether speed selection is momentary or tap-to-select:
  • Momentary: The chosen speed is only active while you hold the respective key. When the key is raised, mouse keys returns to the unmodified speed.
  • Tap-to-select: The chosen speed is activated when you press the respective key and remains active even after the key has been raised. The default speed is that of KC_ACL1. There is no unmodified speed.
The default speeds from slowest to fastest are as follows:
  • Momentary: KC_ACL0 < KC_ACL1 < unmodified < KC_ACL2
  • Tap-to-select: KC_ACL0 < KC_ACL1 < KC_ACL2
To use constant speed mode, you must at least define MK_3_SPEED in your keymap’s config.h file:
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#define MK_3_SPEED
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To enable momentary mode, also define MK_MOMENTARY_ACCEL:
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#define MK_MOMENTARY_ACCEL
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Use the following settings if you want to adjust cursor movement or scrolling:
Define
Default
Description
MK_3_SPEED
Not defined
Enable constant cursor speeds
MK_MOMENTARY_ACCEL
Not defined
Enable momentary speed selection
MK_C_OFFSET_UNMOD
16
Cursor offset per movement (unmodified)
MK_C_INTERVAL_UNMOD
16
Time between cursor movements (unmodified)
MK_C_OFFSET_0
1
Cursor offset per movement (KC_ACL0)
MK_C_INTERVAL_0
32
Time between cursor movements (KC_ACL0)
MK_C_OFFSET_1
4
Cursor offset per movement (KC_ACL1)
MK_C_INTERVAL_1
16
Time between cursor movements (KC_ACL1)
MK_C_OFFSET_2
32
Cursor offset per movement (KC_ACL2)
MK_C_INTERVAL_2
16
Time between cursor movements (KC_ACL2)
MK_W_OFFSET_UNMOD
1
Scroll steps per scroll action (unmodified)
MK_W_INTERVAL_UNMOD
40
Time between scroll steps (unmodified)
MK_W_OFFSET_0
1
Scroll steps per scroll action (KC_ACL0)
MK_W_INTERVAL_0
360
Time between scroll steps (KC_ACL0)
MK_W_OFFSET_1
1
Scroll steps per scroll action (KC_ACL1)
MK_W_INTERVAL_1
120
Time between scroll steps (KC_ACL1)
MK_W_OFFSET_2
1
Scroll steps per scroll action (KC_ACL2)
MK_W_INTERVAL_2
20
Time between scroll steps (KC_ACL2)

Combined mode

This mode functions like Accelerated mode, however, you can hold KC_ACL0, KC_ACL1 and KC_ACL2 to momentarily (while held) set the cursor and scroll speeds to constant speeds. When no acceleration keys are held, this mode is identical to Accelerated mode, and can be modified using all of the relevant settings.
  • KC_ACL0: This acceleration sets your cursor to the slowest possible speed. This is useful for very
    small and detailed movements of the cursor.
  • KC_ACL1: This acceleration sets your cursor to half the maximum (user defined) speed.
  • KC_ACL2: This acceleration sets your cursor to the maximum (computer defined) speed. This is
    useful for moving the cursor large distances without much accuracy.
To use constant speed mode, you must at least define MK_COMBINED in your keymap’s config.h file:
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#define MK_COMBINED
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Use with PS/2 Mouse and Pointing Device

Mouse keys button state is shared with PS/2 mouse and pointing device so mouse keys button presses can be used for clicks and drags.
Last modified 9mo ago