As a best-in-class RTOS, Zephyr™ brings many benefits to ZMK, such as:
- A single platform supporting many architectures, processors and boards.
- Optimization for low-powered, small memory footprint devices.
- Powerful hardware abstraction and configuration using DeviceTree and Kconfig.
- A BLE stack that periodically obtains qualification listings, making it easier for final products to obtain qualification from the Bluetooth® SIG.
- Multi-processor support, which is critical for power efficiency in upcoming MCUs.
- Permissive licensing with its Apache 2.0 open source license.
- A buzzing developer community including many leading embedded technology companies.
- Long term support (LTS) with security updates.
Why yet another keyboard firmware?
That’s an excellent question! There are already great keyboard firmwares available, but ZMK has some advantages:
- See Why Zephyr™?
- Just like other open source firmware, ZMK is all about the free and the sharing. However, some other projects use the GPL license which prevents integration of libraries and drivers whose licenses are not GPL-compatible (such as some embedded BLE drivers). ZMK uses the permissive MIT license which doesn’t have this limitation.
- Wireless First
- ZMK is designed for the future, and we believe the future is wireless. So power efficiency plays a critical role in every design decision, just like in Zephyr™.
The ZMK contributors firmly believe that a keyboard firmware built on Zephyr™ will provide more long term benefits.
What license does ZMK use?
ZMK uses the MIT license.
What hardware/platforms does ZMK support?
ZMK has the potential to run on any platform supported by Zephyr™. However, it’s impractical for the ZMK contributors to test all possible hardware.
The Zephyr™ documentation describes which hardware is currently natively supported by the Zephyr™ platform. Similar documentation covering which keyboards have been integrated into ZMK is currently being planned.
Does ZMK compile for AVR?
Sorry, Zephyr™ only supports 32-bit and 64-bit platforms.
How do I get started?
ZMK is still in its infancy, so there’s a learning curve involved. But if you’d like to try it out, please check out the development documentation and the other FAQs. Please keep in mind that the project team is still small, so our support capability is limited whilst we focus on development. But we’ll try our best! Interested developers are also very welcome to contribute!
What is a “board”?
In ZMK, a board defines the PCB that includes the MCU. For keyboards, this is one of two options:
- Complete keyboard PCBs that include the MCU (e.g. the Planck or Preonic).
- Small MCU boards (e.g. the Proton-C or nice!nano) that expose pins and are designed to be combined with larger keyboard PCBs, or hand wired to switches to create the final keyboard.
What is a “shield”?
In ZMK, a shield is a PCB or hardwired set of components that when combined with a MCU only board like the Proton-C or nice!nano, results in a complete usable keyboard. Examples would be keyboard PCBs like the Kyria or Corne. The shield is usually the big PCB containing all the keys.
Why boards and shields? Why not just “keyboard”?
If you haven't already done so, please read these FAQs first:
When a keyboard accepts a small “PCB MCU module” (e.g. Arduino Pro Micro) for its “brains”, then it's important to conceptually separate the hardware into a board PCB and a shield PCB.
The shield is a brainless shell containing all the keys, RGB LEDs, encoders etc. It maps all of these features to a standard pin footprint, such as the Pro Micro pinout.
To bring this brainless shield to life, you attach any MCU board matching the footprint. For instance, the nice!nano is pin-compatible with the Arduino Pro Micro, so you can substitute either board onto the shield. But each board comes with its own features (MCU, flash, BLE, etc.) which must also be handled.
Therefore in ZMK, board and shield are considered two different (but related) entities so that it’s easier to mix and match them. They are combined during a ZMK build.
Please note, many keyboards only have a single PCB which includes the “brains” (MCU) onboard. In ZMK, these have no shield, only a board.
Does ZMK support wired split?
Currently, ZMK only supports wireless split, but wired split is possible and we welcome contributions!
How is the latency?
The latency of ZMK is comparable to other firmware offerings. ZMK is equipped with a variety of scanning methods and debounce algorithms that can affect the final measured latency. This video shows a latency comparison of ZMK and other keyboard firmwares.
Any chance for 2.4GHz dongle implementation?
At this time, there are no current plans to implement 2.4GHz dongle mode. This is because utilizing Nordic's proprietary 2.4GHz low level protocols requires use of the Nordic Connect SDK, which is licensed with a more restrictive license than ZMK's MIT license. However, ZMK does plan to implement dongle mode using BLE (with encryption). This will result in a 3.75ms average latency from the protocol itself.
What bootloader does ZMK use?
ZMK isn’t designed for any particular bootloader, and supports flashing different boards with different flash utilities (e.g. OpenOCD, nrfjprog, etc.). So if you have any difficulties, please let us know on Discord!
Can I contribute?
Of course! Please use the developer documentation to get started!
I have an idea! What should I do?
Please join us on Discord and discuss it with us!
I want to add a new keyboard! What should I do?
The exact process for the management of all the possible hardware is still being finalized, but any developer looking to contribute new keyboard definitions should chat with us on Discord to get started.
Does ZMK have a Code of Conduct?
Yes, it does have a Code of Conduct! Please give it a read!
What does “ZMK” mean?
ZMK was originally coined as a quasi-acronym of “Zephyr Mechanical Keyboard” and also taking inspiration from the amazing keyboard firmware projects, TMK and QMK.
Is ZMK related to TMK or QMK?
No. But inspired by, of course!
Who created ZMK?
ZMK was created by Pete Johanson. It is developed and maintained by the open source community.