nix-nrf-dev

NCS SDKs and toolchains live outside the Nix store. Their environment scripts can affect host tools. CMSIS-DAP probes need host udev rules before they can flash nRF5340 and nRF54L15 boards.

nix-nrf-dev provides a project-scoped Nix shell for NCS builds and OpenOCD flashing.

The nix-nrf-dev project version is independent from NCS versions. nix-nrf --version reports the nix-nrf-dev project version from release.json, e.g. 0.1.0, while ncsVersion (e.g. v3.3.0) is the upstream SDK selection. See CHANGELOG.md.

What it provides

• nix develop provides west, the Zephyr toolchain, and ZEPHYR_BASE for the selected NCS release.
• openocd-master and udev guidance support CMSIS-DAP probe access.
• nix-nrf provides bootstrap, versions, probes, and doctor.
• init-project writes .envrc and flake.nix pinned to one NCS release.
• Manual hardware tests cover nRF5340 and nRF54L15 flashing.

Quick start

Requires Nix with flake support on x86_64-linux. direnv is optional.

Create a project

mkdir my-project && cd my-project
nix run github:qarnet/nix-nrf-dev#init-project -- .
direnv allow        # or: nix develop
nix-nrf bootstrap   # installs NCS SDK + toolchain (several GiB; prompts first)
nix-nrf doctor      # verify environment and probe access

The initializer writes exactly .envrc and flake.nix, pinned to a concrete NCS release (never latest), and never overwrites existing files. First use builds openocd-master from source (~10 min) unless Cachix is enabled (cachix use qarnet).

Add nix-nrf-dev to an existing project

Add nix-nrf-dev to your project's flake.nix:

{
  inputs.nix-nrf-dev.url = "github:qarnet/nix-nrf-dev";

  outputs = { nix-nrf-dev, ... }: {
    devShells.x86_64-linux.default =
      nix-nrf-dev.lib.x86_64-linux.mkNrfShell {
        backend = "nrfutil";   # default; "west" is experimental
        ncsVersion = "v3.3.0"; # required, exact release, never "latest"
      };
  };
}

nix develop         # or: direnv allow
nix-nrf bootstrap
nix-nrf doctor

See docs/install.md for prerequisites, install locations, release pins, and backend selection.

Everyday commands

nix-nrf bootstrap    # provision the NCS SDK/toolchain (prompts before multi-GiB downloads)
nix-nrf versions     # list available NCS versions
nix-nrf probes       # list attached debug probes and targets
nix-nrf doctor       # read-only environment and probe-access diagnostics
nix-nrf --version    # print the nix-nrf-dev project version (independent from NCS)

Backend-specific behavior and hardware setup live in docs/backends.md and docs/hardware.md.

Note

Packaged nrfutil includes J-Link and its unfree license even when using a CMSIS-DAP probe. Default flake configuration accepts it. Custom nrfutil or Nixpkgs compositions may need the same license configuration. See docs/backends.md#segger--j-link-caveat.

Hardware access

A Nix dev shell cannot set host udev policy. The packaged 60-openocd.rules is the unmodified OpenOCD contrib rule. It needs a plugdev group with your user as a member. On NixOS, set services.udev.packages directly or import nixosModules.udevRules. Both add only the rule. Other Linux distributions install the packaged rule through their normal udev procedure. nix-nrf doctor reports probe visibility and access. See docs/hardware.md.

Documentation

• docs/install.md covers installation and release pins.
• CHANGELOG.md records project releases.
• docs/backends.md explains backends and bootstrap.
• docs/hardware.md covers probes, flashing, and recovery.
• CONTRIBUTING.md explains repository work.

License

MIT. See LICENSE.