<\/p>\n
<\/p>\n
The short version: ZMK<\/a> must be set up for v0.3, not the latest version (as of 2026-06-22), otherwise the result is a compile error. The command line for compiling is:<\/p>\n Keychron released the source code<\/a> for V6 Ultra 8K<\/a> on 2026-05-23 in branch “rtl8762g”<\/em><\/strong><\/a> in Keychron’s fork of ZMK (in the same fork<\/a> as the source code for B6 Pro<\/a>), but they didn’t provide any<\/em><\/strong> instructions on how to compile and flash the keyboard firmware.<\/p>\n Locations:<\/p>\n <\/p>\n Below are the (linear) command lines to set up the main ZMK project on a Debian<\/a>-like system (LMDE<\/a>, Linux Mint<\/a>, Ubuntu<\/a>, Debian itself, Lubuntu<\/a>, Kubuntu<\/a>, Xubuntu<\/a>, BunsenLabs<\/a>, Linux Lite<\/a>, WSL<\/a>, etc.), and compile the keyboard firmware for the V6 Ultra 8K. It would be similar for other (Linux) systems and other keyboards in the V Ultra 8K series and Q Ultra 8K series.<\/p>\n Note that the installation is for ZMK v0.3 (matching the effective ZMK version of Keychron’s fork), similar to the setup described in the blog post for B6 Pro<\/a> (though at that time using the latest ZMK instructions did work; that was before the December 2025 breaking change<\/a> in ZMK. The instructions in that blog post still works (as they are essentially a copy of the instructions at the time), but not the instructions it references).<\/p>\n Thus, the install instructions for v0.3<\/a> apply, not<\/em><\/strong> the latest ZMK instructions. Otherwise, the result would be a compile error:<\/p>\n “ModuleNotFoundError: No module named ‘elftools’<\/em><\/strong>”<\/p>\n Other notes:<\/p>\n Warning<\/em><\/strong>: Note that with “–assume-yes” (“-y” = “–yes” = “–assume-yes”) for ‘sudo apt upgrade’ and ‘apt install’, the upgrade and installation of the ZMK prerequisites becomes unconditional<\/em><\/strong> (so that pasting all the lines after “sudo ls > \/dev\/null” can become one single step). For a more cautious approach, remove the two “–assume-yes”s and upgrade and install the prerequisites as separate steps.<\/p>\n The time is dominated by these two steps, taking about eight minutes each on my system:<\/p>\n The space is about 1.9 GB on disk, in about 49,000 files and 11,000 folders.<\/p>\n The 1.9 GB happens to be about the same as QMK<\/a>. For both ZMK and QMK<\/a>, most of the space is due to the underlying RTOS<\/a> (Zephyr<\/a> and ChibiOS\/RT<\/a> (for ARM microcontrollers), respectively) and their (source code) dependencies (libraries), not the keyboard project themselves. Even the 2,000 supported keyboards in QMK (separate from the core of QMK) “only” takes up about 15 MB.<\/p>\n The initial size for all of ZMK right after Git<\/a> cloning is “only” 40 MB.<\/p>\n The magic command line for compiling the ZMK keyboard firmware for Keychron V8 Ultra 8K is:<\/p>\n <\/p>\n The -p (or –pristine<\/a> (two ASCII dashes, not as rendered here)) is for making sure it works if some other ZMK keyboard was previously compiled. It can often be left out for repeated building, for faster building of the keyboard firmware. See also Pristine Building<\/em><\/a>).<\/p>\n Result:<\/p>\n Here is a transcript<\/a> of both the setup and building. It was tested on an LMDE 7<\/a> (Gigi) system, updated to the latest as of June 2026.<\/p>\n The protocol was reverse engineered<\/a>… And a stand-alone flasher<\/a> was developed (only known to be working on Linux, but it may<\/em> be possible to adapt it for other platforms (it uses raw HID<\/a>, which should be cross-platform)).<\/p>\n Note: The following is for the ‘ISO’ variant, whereas the building above is for the ‘ANSI’ variant (because the source code for the ‘ISO’ variant has not been released yet).<\/p>\n Clone the repository with the flasher, etc.:<\/p>\n Change the hardcoded values in the flasher script:<\/p>\n 1. Change the keyboard identifier<\/a> from KCZKV68K to KCZKV68I<\/a>:<\/p>\n 2. And the same in the print statement<\/a> in function handshake():<\/p>\n 3. Change the USB product ID<\/a> from 0C60 to 0C61 in function find_dfu_hidraw():<\/p>\n <\/p>\n Identify:<\/p>\n Output:<\/p>\n Partly TBD…<\/p>\n It is definitely not the preferred choice, but there is also a browser-based method<\/a>. There is also a claim it is also possible to flash<\/a> using the Via clone<\/a>.<\/p>\n\r\nwest build -p -b keychron -- -DSHIELD=keychron_v6_ultra_ansi\r\n<\/pre>\n
Introduction<\/h2>\n
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Linear command lines to set up from scratch<\/h2>\n
\n
\r\n# Based on the official ZMK install instructions\r\n# (for "native" building) for version v0.3:\r\n#\r\n# <https:\/\/v0-3-branch.zmk.dev\/docs\/development\/local-toolchain\/setup\/native>\r\n#\r\n# Prime sudo. Though only required for\r\n# installing the dependencies, etc.\r\n# And install udev rules, but it may\r\n# have timed out by then...\r\n#\r\nsudo ls > \/dev\/null\r\n\r\n# <https:\/\/docs.zephyrproject.org\/3.5.0\/develop\/getting_started\/index.html#select-and-update-os>\r\nsudo apt update\r\n\r\n# Note: This will upgrade packages which may be\r\n# completely unrelated to the ZMK build,\r\n# for example, package 'dotnet-sdk-10.0'\r\n#\r\nsudo apt-get --assume-yes upgrade\r\n\r\n# Install the required dependencies:\r\nsudo apt-get install\r\n --assume-yes \\\r\n --no-install-recommends \\\r\n git cmake ninja-build gperf \\\r\n ccache dfu-util device-tree-compiler wget \\\r\n python3-dev python3-pip python3-setuptools \\\r\n python3-tk python3-wheel \\\r\n xz-utils file make \\\r\n gcc gcc-multilib g++-multilib \\\r\n libsdl2-dev libmagic1\r\n\r\n\r\ncd $HOME\r\necho ; echo "Start cloning: $(date +%FT%T_%N_ns)" ; echo\r\ngit clone --branch rtl8762g https:\/\/github.com\/Keychron\/zmk.git Keychron_ZMK_fork_rtl8762g_v0_3\r\necho ; echo "End cloning: $(date +%FT%T_%N_ns)" ; echo\r\n\r\n\r\n# Create the virtual Python environment\r\npython3 -m venv $HOME\/.Keychron_Ultra_8K_ZMK_environment_v0_3\r\n\r\n# Enter the virtual Python environment\r\nsource $HOME\/.Keychron_Ultra_8K_ZMK_environment_v0_3\/bin\/activate\r\n\r\n\r\n# ######################################\r\n# Inside the virtual Python environment:\r\n\r\n\r\ncd $HOME\/Keychron_ZMK_fork_rtl8762g_v0_3\r\ngit status # Confirm Git branch "rtl8762g"\r\n\r\n\r\n# Install 'west'\r\n cd $HOME\/Keychron_ZMK_fork_rtl8762g_v0_3\r\n pip install west\r\n\r\n\r\n# Initialise the application and update\r\n# to fetch modules, including Zephyr:\r\n cd $HOME\/Keychron_ZMK_fork_rtl8762g_v0_3\r\n echo ; echo "Start 'west init & update': $(date +%FT%T_%N_ns)" ; echo\r\n sudo ls > \/dev\/null # Refresh the 'sudo' priming.\r\n # Sample timing for this step:\r\n # 08 min 02 secs\r\n\r\n west init -l app\/ # Current directory at the top of\r\n # the cloned repository is assumed\r\n west update\r\n echo ; echo "End 'west init& update': $(date +%FT%T_%N_ns)" ; echo\r\n\r\n\r\n# Export a Zephyr CMake package. This allows CMake to\r\n# automatically load boilerplate code required for\r\n# building Zephyr applications.\r\ncd $HOME\/Keychron_ZMK_fork_rtl8762g_v0_3\r\nwest zephyr-export\r\n\r\n\r\n# Install the additional dependencies found\r\n# in Zephyr's requirements-base.txt\r\n echo ; echo "Start installing additional dependencies: $(date +%FT%T_%N_ns)" ; echo\r\n cd $HOME\/Keychron_ZMK_fork_rtl8762g_v0_3\r\n pip install -r zephyr\/scripts\/requirements-base.txt\r\n echo ; echo "End installing additional dependencies: $(date +%FT%T_%N_ns)" ; echo\r\n\r\n\r\n# It takes a lot of time!\r\n#\r\n# '\/zephyr' is critical...\r\n#\r\n# But on LMDE 6, it failed due to a\r\n# requirement of Python 3.12... It\r\n# apparently only has 3.11.2...\r\n#\r\n# LMDE 7: Python 3.13.5\r\n#\r\n# Starts by downloading the Zyphyr SDK v. 1.0.1\r\n# compressed tar ball (70 MB).\r\n#\r\n# And installs things like (downloading 45 - 145 MB\r\n# for each):\r\n#\r\n# 'arm-zephyr-eabi' GNU toolchain.\r\n# 'riscv64-zephyr-elf' GNU toolchain.\r\n#\r\n# 'Install Zephyr SDK'. Points to Zephyr 3.5 instructions,\r\n# <https:\/\/docs.zephyrproject.org\/3.5.0\/develop\/getting_started\/index.html#install-zephyr-sdk>\r\n#\r\ncd $HOME\r\necho ; echo "Start Zephyr SDK install: $(date +%FT%T_%N_ns)" ; echo\r\nsudo ls > \/dev\/null # Refresh the 'sudo' priming.\r\n # Sample timing for this step:\r\n # 08 min 31 secs\r\n\r\n# 1.2 GB\r\nwget https:\/\/github.com\/zephyrproject-rtos\/sdk-ng\/releases\/download\/v0.16.3\/zephyr-sdk-0.16.3_linux-x86_64.tar.xz\r\n\r\nwget -O - https:\/\/github.com\/zephyrproject-rtos\/sdk-ng\/releases\/download\/v0.16.3\/sha256.sum | shasum --check --ignore-missing\r\n\r\ntar xvf zephyr-sdk-0.16.3_linux-x86_64.tar.xz\r\n\r\n\r\ncd $HOME\/zephyr-sdk-0.16.3\r\n#\r\n# Note: Has several prompts, e.g.,\r\n#\r\n# Install host tools [y\/n]?\r\n#\r\n.\/setup.sh\r\n\r\necho ; echo "End Zephyr SDK install: $(date +%FT%T_%N_ns)" ; echo\r\n\r\n\r\n# Not yet\r\n#sudo cp $HOME\/zephyr-sdk-0.16.3\/sysroots\/x86_64-pokysdk-linux\/usr\/share\/openocd\/contrib\/60-openocd.rules \/etc\/udev\/rules.d\r\n#sudo udevadm control --reload\r\n\r\n\r\n# Exit the virtual Python environment\r\ndeactivate\r\n<\/pre>\n
\n
Building<\/h2>\n
\r\n# Enter the virtual Python environment\r\nsource $HOME\/.Keychron_Ultra_8K_ZMK_environment_v0_3\/bin\/activate\r\n\r\n# Crucial. Otherwise, the result may be\r\n#\r\n# ERROR:\r\n# source directory "." does not contain a CMakeLists.txt;\r\n# is this really what you want to build?\r\n# (Use -s SOURCE_DIR to specify the\r\n# application source directory)\r\n#\r\n# FATAL ERROR: refusing to proceed without --force due to above error\r\n#\r\ncd $HOME\/Keychron_ZMK_fork_rtl8762g_v0_3\/app\r\n\r\nwest build -p -b keychron -- -DSHIELD=keychron_v6_ultra_ansi\r\n\r\n# Exit the virtual Python environment\r\ndeactivate\r\n<\/pre>\n
\r\nMemory region Used Size Region Size %age Used\r\n FLASH: 303620 B 800 KB 37.06%\r\n RAM: 81664 B 100 KB 79.75%\r\n TRACE: 13713 B 512 KB 2.62%\r\n ITCM: 101136 B 104 KB 94.97%\r\n IDT_LIST: 0 GB 2 KB 0.00%\r\n\r\n -rwxrwxr-x 1 embo embo 7565640 Jun 12 10:27 \/home\/embo\/Keychron_ZMK_fork_rtl8762g_v0_3\/app\/build\/zephyr\/zmk.elf\r\n<\/pre>\n
Flashing<\/h2>\n
\r\ngit clone https:\/\/github.com\/naaraxi\/zmk.git -b openrgb $HOME\/Keychron_ZMK_flasher\r\n<\/pre>\n
\r\ngeany $HOME\/Keychron_ZMK_flasher\/openrgb\/flash.py:33\r\n<\/pre>\n
\r\ngeany $HOME\/Keychron_ZMK_flasher\/openrgb\/flash.py:108\r\n<\/pre>\n
\r\ngeany $HOME\/Keychron_ZMK_flasher\/openrgb\/flash.py:58\r\n<\/pre>\n
\r\ncd $HOME\/Keychron_ZMK_flasher\r\nsudo .\/openrgb\/flash.py handshake\r\n<\/pre>\n
\r\nDFU interface: \/dev\/hidraw29\r\n>> GET_MODEL_INFO (0x60)...\r\n model = b'KCZKV68I' fw = b'1.0.1-r'\r\n dfu_version = 0x03 enc_mode = 0\r\n framing\/identity VALID (matches KCZKV68I)\r\n<\/pre>\n
References<\/h2>\n