ZMK Studio

ZMK Studio provides runtime update functionality to ZMK powered devices, allowing users to change their keymap layers without flashing new firmware to their keyboards.

info

To use ZMK Studio, a keyboard needs to be configured appropriately. ZMK has updated some, but not all, of its in-tree keyboards for use with ZMK Studio, the list of which can be found here. If your keyboard is supported by an external module/config, check with the maintainer to see if support has been added.

Capabilities

ZMK Studio currently has the following capabilities:

Legend:	✅ Supported	🚧 Under Development	💡 Planned	🕯️ Low Priority	❌ Not Planned

Status	Feature/Capability
✅	Making keymap changes while keyboard is in use
✅	Making changes while connected via USB
✅	Native app for: Windows, Linux, MacOS
✅	Making changes while connected via BLE (Linux web-app & native apps only)
✅	Assigning predefined behaviors to keys
✅	Assigning user-defined behaviors to keys
💡	Configuring basic behavior properties
💡	Configuring advanced behavior properties, e.g. tap dance, macros,
❌	Defining new behaviors not specified in devicetree
💡	Configuring combos
💡	Configuring conditional layers
🕯️	Assigning behaviors to encoders
✅	Selecting alternative pre-defined physical layouts for the keyboard
❌	Defining new physical layouts for the keyboard
✅	Renaming layers & enabling extra layers
❌	Adding more layers than specified by devicetree
💡	Host locale selection

Items listed as "planned", "under development", "low priority", or "not planned" can be configured using devicetree instead.

Keymap Changes

To unlock your keyboard to allow ZMK Studio to make changes, you'll need to add a &studio_unlock binding to the keymap.

note

Once using ZMK Studio to manage your keymap, any future changes made to the .keymap file for your keyboard will not be applied unless you perform a "Restore Stock Settings" action from the ZMK Studio UI.

Generally, if you intend to use ZMK Studio, then you should not make any further changes to the .keymap file (with the exception of adding new empty layers to then use within ZMK Studio).

Accessing ZMK Studio

You can use ZMK Studio with Chrome/Edge at https://zmk.studio/.

To use the native app for Linux, macOS, or Windows, download the appropriate file from the latest release.

warning

To use ZMK Studio over USB, you need permission to access the USB serial port. This most commonly occurs on Linux, with various distributions having different methods of resolving the error. For example, you may need to be added to a uucp or a dialout group. Refer to your operating system's documentation for more information.

Building

Building for ZMK Studio involves two main additional items.

• Build with the studio-rpc-usb-uart snippet to enable the endpoint used for ZMK Studio communication over USB.
• Enable the ZMK_STUDIO Kconfig setting.

GitHub Actions

Add a studio-rpc-usb-uart to the snippet property of your build configuration, in the build.yaml file at the root of your user config. Enabling the ZMK_STUDIO Kconfig setting can also be done from the build.yaml file using the cmake-args property.

For a split keyboard, you should do this only for your central/left side, e.g.:

build.yaml

---
include:
  - board: nice_nano_v2
    shield: corne_left
    snippet: studio-rpc-usb-uart
    cmake-args: -DCONFIG_ZMK_STUDIO=y
  - board: nice_nano_v2
    shield: corne_right

Local Build

When building locally, use the -S parameter to include the studio-rpc-usb-uart snippet. Instead of adding it to your config file, you can also append the ZMK_STUDIO Kconfig as an additional CMake argument, e.g.:

west build -d build/cl_studio -b nice_nano_v2 \
  -S studio-rpc-usb-uart -- -DSHIELD=corne_left -DCONFIG_ZMK_STUDIO=y

Including Unreferenced Behaviors

Normally, ZMK will only build and include behaviors that are referenced by your keymap and unused behavior will be skipped. However, ZMK Studio builds using the studio-rpc-usb-uart snippet will automatically define the ZMK_BEHAVIORS_KEEP_ALL value, which changes the approach and builds all possible behaviors into the firmware. This lets those behaviors be used in ZMK Studio.

A few controls are available to override this behavior for fine-grained control of what behaviors are built. Behaviors can be kept or omitted by defining certain values in the top of your keymap file, before the standard behaviors.dtsi file is included.

By convention, the defines used to keep/omit a given behavior are typically upper-cased versions of the behavior label, e.g. for the &kt behavior, the suffix to use would be _KT.

Omit Specific Behaviors

You can omit a specific behaviors by defining a variable like ZMK_BEHAVIORS_OMIT_KT at the top of your keymap:

#define ZMK_BEHAVIORS_OMIT_KT

#include <behaviors.dtsi>

Keep Only Selective Behaviors

To override the default "keep all" functionality, you can undefine the ZMK_BEHAVIORS_KEEP_ALL flag, and then keep only specific behaviors with a flag like ZMK_BEHAVIORS_KEEP_KT, e.g.:

#undef ZMK_BEHAVIORS_KEEP_ALL

#define ZMK_BEHAVIORS_KEEP_SK
#define ZMK_BEHAVIORS_KEEP_MT
#define ZMK_BEHAVIORS_KEEP_KT

#include <behaviors.dtsi>

Including Extra Layers

By default, a build with ZMK Studio enabled will only allow as many layers as are defined in your standard keymap. To make additional layers available for use through ZMK Studio, you simply add new empty layers to your keymap with a status of reserved, e.g.:

/ {
    keymap {
        compatible = "zmk,keymap";

        base {
            display-name = "Base";
            bindings = // etc.
        };

        fn_layer {
            display-name = "Fn";
            bindings = // etc.
        };

        extra1 {
            status = "reserved";
        };

        extra2 {
            status = "reserved";
        };
    }
}

The reserved layers will be ignored during regular ZMK builds but will become available for ZMK Studio enabled builds.

Adding ZMK Studio Support to a Keyboard

To allow ZMK Studio to be used with a keyboard, the keyboard will need to have a physical layout with the keys property defined. The keyboard should also not have a chosen zmk,matrix-transform. Relevant information can be found in:

• The dedicated page on physical layouts, informing you how to define one
• The new shield guide, informing you how to select a physical layout once defined
• The corresponding configuration page, for reference

To use the studio-rpc-usb-uart snippet, the keyboard also needs to be configured to allow CDC-ACM console snippets (this is also used for USB logging). If your keyboard is a composite keyboard, consisting of an in-tree board and a shield, then you can skip this step as the board will already be configured properly. Relevant information on that can be found in the Zephyr documentation.

Firmware with ZMK Studio enabled require significantly more RAM. Some MCUs, such as the STM32F072 series, will require fine tuning of various settings in order to reduce the RAM consumption enough for a Studio enabled build to fit.

Finally, once you have successfully built and tested firmware with ZMK Studio enabled, add the studio flag to your keyboard's metadata.