Install

Get hpx and the tools it drives onto your machine. When this page is done, hpx doctor reports every required row as found. Nothing here needs a board attached.

Prerequisites

Python 3.11 or newer on the host (requires-python in pyproject.toml), a package manager (uv or pip), and either an internet connection for the downloads below or the Nix flake, which pins everything. Windows users need long-path support before the first build; the command is in step 1.

Steps

1. Install hpx

uv tool install helia-profiler

uv tool install keeps hpx in its own environment, so the example model shipped inside the package is not importable from your shell; use a source checkout’s examples/quickstart/kws_model.tflite or your own model on the First profile page.

pip install helia-profiler

Installing into an active Python environment also makes the bundled example model available:

python -c "from helia_profiler.examples import tiny_cnn; print(tiny_cnn())"

The repository flake carries every tool on this page, including a pinned J-Link package downloaded from SEGGER under its terms. Install Determinate Nix with the installer on that page, then:

git clone https://github.com/AmbiqAI/helia-profiler.git && cd helia-profiler
nix develop
hpx doctor

The flake supports x86-64 Linux, ARM64 Linux and Apple Silicon macOS. It does not run natively on Windows; use WSL2 (J-Link USB access then needs usbipd-win) or the uv and pip paths. Skip steps 2 to 4 and continue with Linux USB permissions if you are on Linux.

Nix environment covers choosing and pinning the heliaAOT release, the compatibility rules, recording what resolved, and what Nix cannot provide.

On Windows, enable long paths before the first build. Some NSX module checkouts exceed the 260-character MAX_PATH limit; git needs its setting so checkouts can create the files, and the OS policy so Python can traverse and clean them:

git config --global core.longpaths true

# In an elevated (Administrator) PowerShell; new processes pick it up
# immediately, no reboot needed:
Set-ItemProperty -Path HKLM:\SYSTEM\CurrentControlSet\Control\FileSystem `
    -Name LongPathsEnabled -Value 1

Optional extras use the same installer as the base package. To add both compiler and model-analysis support to a uv tool environment:

uv tool install --force 'helia-profiler[aot,analysis]'

For an active Python environment:

pip install 'helia-profiler[aot]'        # heliaAOT compiler support
pip install 'helia-profiler[analysis]'   # model compute and parameter analysis, no hardware

The aot extra installs the supported helia-aot>=0.23.0,<0.27.0 range. Power capture support (pyjoulescope_driver) is a core dependency and needs no extra.

2. Arm GNU toolchain

arm-none-eabi-gcc is the default cross-compiler. armclang and ATfE are alternatives; see Toolchains.

sudo apt install gcc-arm-none-eabi

For a newer compiler than your distribution packages, download the Arm GNU Toolchain tarball and put its bin/ directory on PATH:

export PATH="$HOME/arm-gnu-toolchain-14.3.rel1/bin:$PATH"

Install the macOS package from the Arm GNU Toolchain Downloads page (default location /Applications/ArmGNUToolchain/) and add it to PATH:

export PATH="/Applications/ArmGNUToolchain/14.3.rel1/arm-none-eabi/bin:$PATH"

Run the Windows installer from the same downloads page and tick Add path to environment variable during setup. Verify in a new terminal:

arm-none-eabi-gcc --version

If the command is not found but the toolchain is installed, add its bin directory to PATH (installer default C:\Program Files (x86)\Arm GNU Toolchain arm-none-eabi\<version>\bin):

$env:PATH = "C:\path\to\arm-toolchain\bin;$env:PATH"

3. CMake and Ninja

sudo apt install cmake ninja-build

brew install cmake ninja

winget install Kitware.CMake Ninja-build.Ninja

pip install cmake ninja works if you prefer not to use winget.

4. SEGGER J-Link software

hpx drives the probe through SEGGER Commander (JLinkExe on Linux and macOS, JLink.exe on Windows) for flashing, and through pylink-square, installed with hpx, for RTT and SWO capture. Discovery checks JLINK_PATH first, then both executable names on PATH, then the common SEGGER install locations; set JLINK_PATH to the full executable path for a non-standard install.

Install the .deb or .tgz from segger.com/downloads/jlink. The SEGGER installer sets up the udev rules for non-root access to the probe; replug the probe afterwards if hpx probes list does not see it.

Run the .pkg installer from segger.com/downloads/jlink.

Run the .exe installer from segger.com/downloads/jlink. Drivers install automatically. The software lands in a versioned directory (C:\Program Files\SEGGER\JLink_V<version>) and hpx finds it there without a PATH entry.

hpx bundles a pinned copy of the permissively licensed SEGGER RTT target sources, so no separate RTT checkout is needed. To test another RTT release, hpx resolves overrides in this order: target.segger_rtt_path in configuration, then the SEGGER_RTT_PATH environment variable, then the bundled sources. An override directory must contain RTT/SEGGER_RTT.c and Config/SEGGER_RTT_Conf.h.

5. Linux USB permissions

Installing tools does not grant access to attached hardware. J-Link and Joulescope are raw USB devices; uart and usb_cdc transports also need the serial device (/dev/ttyACM0, /dev/ttyUSB0). Run hpx as your normal user after granting access.

On a desktop Linux host, from a source checkout:

nix run .#install-udev-rules -- --dry-run
nix run .#install-udev-rules

Without Nix, run bash nix/scripts/install-udev-rules.sh. The installer writes 70-segger-jlink.rules and 70-joulescope.rules under /etc/udev/rules.d/, reloads the rules and refreshes USB devices; unplug and reconnect the instruments afterwards. The rules grant the active local desktop session access through uaccess, not every user.

On NixOS, declare the rules in the system configuration instead:

services.udev.packages = [
  (pkgs.writeTextDir "lib/udev/rules.d/70-hpx.rules" ''
    SUBSYSTEM=="usb", ATTR{idVendor}=="1366", MODE="0660", TAG+="uaccess", ENV{ID_MM_DEVICE_IGNORE}="1"
    SUBSYSTEM=="usb", ENV{DEVTYPE}=="usb_device", ATTRS{idVendor}=="16d0", ATTRS{idProduct}=="0e88|0e87|10ba|10b9|135a", MODE="0660", TAG+="uaccess"
  '')
];

Use services.udev.packages, not services.udev.extraRules, which NixOS writes after the active-session access handler.

For SSH sessions and CI runners, which have no local desktop session, give a dedicated group access:

sudo groupadd -f hpx
sudo usermod -aG hpx "$USER"
sudo tee /etc/udev/rules.d/70-hpx-group.rules >/dev/null <<'RULES'
SUBSYSTEM=="usb", ATTR{idVendor}=="1366", GROUP="hpx", MODE="0660", ENV{ID_MM_DEVICE_IGNORE}="1"
SUBSYSTEM=="usb", ENV{DEVTYPE}=="usb_device", ATTRS{idVendor}=="16d0", ATTRS{idProduct}=="0e88|0e87|10ba|10b9|135a", GROUP="hpx", MODE="0660"
RULES
sudo udevadm control --reload-rules
sudo udevadm trigger --subsystem-match=usb

For serial ports, check the device’s owning group with ls -l /dev/ttyACM0 and add yourself to it (dialout on Ubuntu and Debian); the raw-USB rules do not cover /dev/tty*.

Expected output

hpx doctor prints one row per tool. Captured on macOS 26.6 on 2026-09-21 with the tools installed as above:


        $
        hpx doctor
      
        
        Toolchain Check
      
        
        ╭────┬───────────────────────────────────────┬─────────────────────────────────────────────────────╮
      
        
        │    │ Tool                                  │ Path                                                │
      
        
        ├────┼───────────────────────────────────────┼─────────────────────────────────────────────────────┤
      
        
        │ ✓  │ CMake (>= 3.24)                       │ /opt/homebrew/bin/cmake                             │
      
        
        │ ✓  │ Ninja build system                    │ /opt/homebrew/bin/ninja                             │
      
        
        │ ✓  │ SEGGER J-Link commander               │ /usr/local/bin/JLinkExe                             │
      
        
        │ ✓  │ neuralspotx Python package            │ installed                                           │
      
        
        │ ✓  │ ARM GCC toolchain                     │ /Applications/ArmGNUToolchain/15.2.rel1/arm-none-e… │
      
        
        │ ✓  │ pylink Python package (RTT transport) │ installed                                           │
      
        
        ╰────┴───────────────────────────────────────┴─────────────────────────────────────────────────────╯
      
        
         
      
        
          All required tools found.

A dash in the first column marks an optional tool that was not found (heliaAOT, armclang); those rows only matter if you use that engine or toolchain. hpx doctor checks presence, not versions: the minimum versions are on Hardware prerequisites.

What next

Hardware prerequisites lists what to plug in. If the board is already on the bench, go straight to Validate your setup.