First boot

Complete Installation first. The commands below use Windows paths. On Linux and macOS, use the executable names and debugger options from the installation guide.

Prepare the storage

QEMU needs files that stand in for the watch’s storage. They contain the app, its fonts and images, and the language setting. The CLI uses the reference firmware to create these files on your computer.

1. Download the pinned SDK NAND ID file and save it as runtime/nand_id_all.bin. It tells the stock driver which kind of flash chip the emulator presents. You only need that one SDK file.
2. Install an Arm debugger. On Windows, use an Arm GNU Toolchain distribution containing arm-none-eabi-gdb.exe. Add its bin folder to PATH or pass the full path in quotes after --gdb. Run arm-none-eabi-gdb --version to check it. The debugger is used here to start the storage setup inside QEMU.
3. Leave at least 250 MiB free on the drive. Run this from the checkout:

uv run cmf-watch-utils emu prepare-fixtures --fixtures fixtures --stock dumps/binaries/firmware/JX402_V1.0.0.73.bin --nand-id runtime/nand_id_all.bin --qemu runtime/qemu-system-arm.exe --rom runtime/compat.bin --runtime-dir C:/msys64/ucrt64/bin --provisioner runtime --gdb arm-none-eabi-gdb

The command prints where it saved the storage files and logs. The fixtures folder should contain nor.bin, nand-id.bin and nand-defaults.bin. Keep them for future runs. If you already have these three files from a previous setup, reuse them and go to Headless boot.

Headless boot

First run without opening a window. This checks that the virtual watch starts and draws something:

uv run cmf-watch-utils emu run --fixtures fixtures --qemu runtime/qemu-system-arm.exe --rom runtime/compat.bin --runtime-dir C:/msys64/ucrt64/bin --headless --output runs/first-boot

Look for "panel_frame_captured": true in the output. QEMU saves a screenshot as runs/first-boot/frame.ppm and its result as report.json.

Open the viewer

Run again with a new output folder:

uv run cmf-watch-utils emu run --fixtures fixtures --qemu runtime/qemu-system-arm.exe --rom runtime/compat.bin --runtime-dir C:/msys64/ucrt64/bin --output runs/first-window

You should see a window titled CMF Watch Pro 2. For the first-run language screen, repeat the storage preparation with --profile wp2-onboarding, then add that flag to your boot command. Every boot command needs a new output folder. Use a different name to keep older results.

Windowed runs select an available speaker backend automatically. Use --audio none for a silent window. To record the speaker output to audio.wav without opening a window, run with --headless --wav.

Custom firmware

Use --app local/app.bin to start an app you built. Add --sdfs local/sdfs.bin if it needs a matching resource archive. Use --ota-image local/update.bin to extract the app and resources from a supported update and boot them directly. That direct boot checks whether the app starts and renders. Use OTA and recovery to test transfer and installation.

uv run cmf-watch-utils emu preflight --image local/update.bin

Preflight means checking a package without running it. The command checks the target board, checksums, and whether the app and its resources fit. It only needs the Python workspace and the update file. Some factory packages include extra partitions. Use fwkit to inspect those.

Troubleshooting

What you see	What to check
Firmware hash mismatch or a tiny firmware file	Repeat step 2 in Setup to download the full reference image.
ats3089c-wp2 missing	Point --qemu at the executable from the preview archive.
QEMU exits before boot	Rerun emu doctor. On Windows, check that --runtime-dir points to MSYS2’s UCRT64 bin folder.
Storage preparation fails	Check free space, the debugger path, and the numbered GDB, QEMU and UART logs in the reported folder.
Headless works but the window fails	Install Tcl/Tk and pass --wish with the path to its executable if it is outside PATH.