Auto Shift

Tap a key and you get its character. Tap a key, but hold it slightly longer and you get its shifted state. Voilà! No shift key needed!

Why Auto Shift?

Many people suffer from various forms of RSI. A common cause is stretching your fingers repetitively long distances. For us on the keyboard, the pinky does that all too often when reaching for the shift key. Auto Shift looks to alleviate that problem.

How Does It Work?

When you tap a key, it stays depressed for a short period of time before it is then released. This depressed time is a different length for everyone. Auto Shift defines a constant AUTO_SHIFT_TIMEOUT which is typically set to twice your normal pressed state time. When you press a key, a timer starts, and if you have not released the key after the AUTO_SHIFT_TIMEOUT period, then a shifted version of the key is emitted. If the time is less than the AUTO_SHIFT_TIMEOUT time, or you press another key, then the normal state is emitted.

If AUTO_SHIFT_REPEAT is defined, there is keyrepeat support. Holding the key down will repeat the shifted key, though this can be disabled with AUTO_SHIFT_NO_AUTO_REPEAT. If you want to repeat the normal key, then tap it once then immediately (within TAPPING_TERM) hold it down again (this works with the shifted value as well if auto-repeat is disabled).

Are There Limitations to Auto Shift?

Yes, unfortunately.

You will have characters that are shifted when you did not intend on shifting, and other characters you wanted shifted, but were not. This simply comes down to practice. As we get in a hurry, we think we have hit the key long enough for a shifted version, but we did not. On the other hand, we may think we are tapping the keys, but really we have held it for a little longer than anticipated.

Additionally, with keyrepeat the desired shift state can get mixed up. It will always 'belong' to the last key pressed. For example, keyrepeating a capital and then tapping something lowercase (whether or not it's an Auto Shift key) will result in the capital's key still being held, but shift not.

How Do I Enable Auto Shift?

Add to your in the keymap folder:


If no exists, you can create one.

Then compile and install your new firmware with Auto Key enabled! That's it!


By default, Auto Shift is disabled for any key press that is accompanied by one or more modifiers. Thus, Ctrl+A that you hold for a really long time is not the same as Ctrl+Shift+A.

You can re-enable Auto Shift for modifiers by adding a define to your config.h


In which case, Ctrl+A held past the AUTO_SHIFT_TIMEOUT will be sent as Ctrl+Shift+A

Configuring Auto Shift

If desired, there is some configuration that can be done to change the behavior of Auto Shift. This is done by setting various variables the config.h file located in your keymap folder. If no config.h file exists, you can create one.

A sample is

#pragma once


This controls how long you have to hold a key before you get the shifted state. Obviously, this is different for everyone. For the common person, a setting of 135 to 150 works great. However, one should start with a value of at least 175, which is the default value. Then work down from there. The idea is to have the shortest time required to get the shifted state without having false positives.

Play with this value until things are perfect. Many find that all will work well at a given value, but one or two keys will still emit the shifted state on occasion. This is simply due to habit and holding some keys a little longer than others. Once you find this value, work on tapping your problem keys a little quicker than normal and you will be set.

?> Auto Shift has three special keys that can help you get this value right very quick. See "Auto Shift Setup" for more details!

NO_AUTO_SHIFT_SPECIAL (simple define)

Do not Auto Shift special keys, which include -_, =+, [{, ]}, ;:, '", ,<, .>, and /?

NO_AUTO_SHIFT_NUMERIC (simple define)

Do not Auto Shift numeric keys, zero through nine.

NO_AUTO_SHIFT_ALPHA (simple define)

Do not Auto Shift alpha characters, which include A through Z.

Auto Shift Per Key

This is a function that allows you to determine which keys shold be autoshifted, much like the tap-hold keys.

The default function looks like this:

bool get_auto_shifted_key(uint16_t keycode, keyrecord_t *record) {
switch (keycode) {
case KC_A ... KC_Z:
# endif
case KC_1 ... KC_0:
# endif
case KC_TAB:
# endif
return true;
return false;

This functionality is enabled by default, and does not need a define.

AUTO_SHIFT_REPEAT (simple define)

Enables keyrepeat.


Disables automatically keyrepeating when AUTO_SHIFT_TIMEOUT is exceeded.

Using Auto Shift Setup

This will enable you to define three keys temporarily to increase, decrease and report your AUTO_SHIFT_TIMEOUT.


Map three keys temporarily in your keymap:

Key Name



Lower the Auto Shift timeout variable (down)


Raise the Auto Shift timeout variable (up)


Report your current Auto Shift timeout value


Turns on the Auto Shift Function


Turns off the Auto Shift Function


Toggles the state of the Auto Shift feature

Compile and upload your new firmware.


It is important to note that during these tests, you should be typing completely normal and with no intention of shifted keys.

  1. Type multiple sentences of alphabetical letters.

  2. Observe any upper case letters.

  3. If there are none, press the key you have mapped to KC_ASDN to decrease

    time Auto Shift timeout value and go back to step 1.

  4. If there are some upper case letters, decide if you need to work on tapping

    those keys with less down time, or if you need to increase the timeout.

  5. If you decide to increase the timeout, press the key you have mapped to

    KC_ASUP and go back to step 1.

  6. Once you are happy with your results, press the key you have mapped to

    KC_ASRP. The keyboard will type by itself the value of your


  7. Update AUTO_SHIFT_TIMEOUT in your config.h with the value reported.

  8. Add AUTO_SHIFT_NO_SETUP to your config.h.

  9. Remove the key bindings KC_ASDN, KC_ASUP and KC_ASRP.

  10. Compile and upload your new firmware.

An Example Run

hello world. my name is john doe. i am a computer programmer playing with
keyboards right now.
[PRESS KC_ASDN quite a few times]
heLLo woRLd. mY nAMe is JOHn dOE. i AM A compUTeR proGRaMMER PlAYiNG witH
[PRESS KC_ASUP a few times]
hello world. my name is john Doe. i am a computer programmer playing with
keyboarDs right now.

The keyboard typed 115 which represents your current AUTO_SHIFT_TIMEOUT value. You are now set! Practice on the D key a little bit that showed up in the testing and you'll be golden.