axR — Interfacing and retrieving data from accelerometer devices • axR

Device discovery, status, settings, and data download for accelerometer devices.

📖 What is axR?

axR talks to Axivity AX3/AX6 accelerometers over USB: discovering connected devices, querying and setting status/configuration, and downloading recorded .cwa files. It also parses those .cwa files directly, and – as of a recent addition – Condor Instruments ActTrust .txt actigraphy exports, into the same tidy epoch shape.

Rather than reimplementing the Axivity serial protocol directly, axR wraps the Open Movement Project’s OMAPI C library (vendored in src/omapi, BSD 2-clause, Newcastle University — see src/omapi/LICENSE.TXT). OMAPI is the same library behind Axivity’s own OmGui software, and includes maintained, platform-specific device discovery (IOKit/DiskArbitration on macOS, SetupAPI on Windows, udev on Linux) rather than a hand-rolled equivalent.

axR is deliberately mostly a “dumb pipe” — it talks to the device and moves bytes, leaving higher-level actigraphy analysis to downstream packages such as mrpheus or zeitR. axivity_read_cwa() and read_acttrust() are deliberate exceptions: OMAPI already ships a complete .cwa reader, and ActTrust’s .txt export format is a plain, well-specified text format – so axR wraps/parses both directly rather than building a second, differently-sourced parser for either. read_acttrust() deliberately stops at device-format parsing, though: it returns the file’s own epoch columns with no pipeline-specific columns or classes added, leaving that reshaping to downstream packages (e.g. zeitR), the same way axivity_read_cwa() does.

[!WARNING] axR has not been fully verified against real hardware. Live-device testing was performed on macOS and a real AX3. timestamp/x/y/z/device_id from axivity_read_cwa() have been verified correct against a real recording; temperature_c has not, and is likely wrong on at least some hardware revisions. Not tested against an AX6.

✨ Features

🔍 Discovery — axivity_discover()
📊 Status — battery, self-test, memory health, live accelerometer reading, RTC get/set, LED colour, anti-tamper lock, ECC flag, and a raw axivity_send_command() escape hatch
⚙️ Settings — delayed activation window, session ID, metadata scratch buffer, accelerometer rate/range, and axivity_reset() (erase + commit, with none/delete/quickformat/wipe levels)
🧰 axivity_stage_device() — one-call deployment staging: sets accelerometer config, deployment window (as start/stop or start/duration), session ID, and metadata, then commits with axivity_reset(). For finer control, the underlying axivity_set_*() functions and axivity_reset() remain available individually
📥 Download — axivity_download(), backed by OMAPI’s own background download thread (progress polling and cancellation included), not a plain file copy
📂 axivity_copy_data() — fallback: plain file copy from a mounted device volume, bypassing OMAPI/device_id entirely, for when axivity_discover() isn’t finding the device but its mass-storage mount still works
🧮 axivity_read_cwa() — parse a .cwa/AX6 file directly (via OMAPI’s own binary reader) into a tibble ready for downstream actigraphy analysis — no live device or prior discovery required
📋 read_acttrust() — parse a Condor Instruments ActTrust .txt export into the same tidy epoch shape, as a device-agnostic actigraphy import layer alongside axivity_read_cwa() – no live device required
🐞 axivity_enable_debug_log() — re-enable OMAPI’s internal diagnostic trace, for debugging device-detection issues

There’s no axivity_open()/close() step — the OMAPI session starts when axR is loaded and stops when it’s unloaded. Every device-facing function takes a device_id from axivity_discover().

🗂️ Project Structure

axR/
├── configure              # generates src/Makevars at install time (chmod +x!)
├── cleanup                # removes configure/build artefacts (chmod +x!)
├── R/
│   ├── axR-package.R   # package-level documentation
│   ├── zzz.R            # .onLoad/.onUnload (OmStartup/OmShutdown), .om_check()
│   ├── discover.R        # axivity_discover(), axivity_enable_debug_log()
│   ├── status.R          # battery, self-test, memory health, accelerometer,
│   │                       # RTC, LED, lock, ECC, send_command
│   ├── settings.R        # delays, session ID, metadata, accel config, reset
│   ├── stage.R            # axivity_stage_device() -- one-call deployment staging
│   ├── download.R        # data info, download, download_status/wait/cancel,
│   │                       # axivity_copy_data()
│   ├── read_cwa.R        # axivity_read_cwa()
│   ├── read_acttrust.R   # read_acttrust()
│   └── utils.R           # internal message helpers (axr_abort/warn/inform), %||%
├── src/
│   ├── axR-omapi.cpp     # thin Rcpp wrapper around OMAPI
│   ├── omapi/             # vendored OMAPI C library (BSD 2-clause), with
│   │                       # axR patches -- see inline comments and NEWS.md
│   ├── Makevars.in       # template; configure fills in the platform-specific bits
│   └── Makevars.win      # Windows build config (static, no template needed)
├── vignettes/
│   ├── axR.Rmd.orig      # real vignette source (not shipped)
│   └── axR.Rmd           # pre-computed output, knitr::knit()'d from .orig
├── tests/testthat/
├── man/figures/
│   ├── logo.svg
│   └── logo.png
├── pkgdown/favicon/      # via pkgdown::build_favicons()
├── .github/workflows/    # R-CMD-check.yaml, pkgdown.yaml
├── _pkgdown.yml
├── DESCRIPTION
└── NEWS.md

🚀 Getting Started

Prerequisites

R (>= 4.1.0)
Rcpp
A C/C++ toolchain (Xcode CLT on macOS, Rtools44 on Windows)
Linux only: libudev-dev (or equivalent) for device discovery

Installation

Install from r-universe (recommended — pre-built binaries):

install.packages(
  "axR",
  repos = c("https://circadia-bio.r-universe.dev", "https://cloud.r-project.org")
)

Or install the development version from GitHub:

install.packages("pak")
pak::pak("circadia-bio/axR")

Linux only: r-universe’s pre-built binaries don’t bundle system libraries — libudev-dev (or equivalent) still needs to be installed separately on the machine running R, regardless of install method.

Vignette

vignette("axR")

Walks through discovery, status/settings, deployment staging with axivity_stage_device(), downloading, the axivity_copy_data() fallback, and reading .cwa files with axivity_read_cwa().

📦 Dependencies

Package	Type	Purpose
Rcpp	Imports	Bridges R to the vendored OMAPI C library
cli	Imports	`read_acttrust()`’s error/warning messages
lubridate	Imports	`read_acttrust()`’s flexible date-time parsing
tibble	Suggests	`axivity_read_cwa()`/`read_acttrust()`’s return type (falls back to a plain data frame if absent)
testthat	Suggests	Test suite
covr	Suggests	Coverage reporting
knitr, rmarkdown, pkgdown	Suggests	Vignette and documentation site

👥 Authors

Role	Name	Affiliation
Author, maintainer	Lucas França	Circadia Lab, Northumbria University
Author	Mario Leocadio-Miguel	Circadia Lab, Northumbria University
Author	Daniel Jackson	Northumbria University

📄 Citation

If you use axR in your research, please cite it:

@software{franca_axr_2026,
  author  = {França, Lucas and Leocadio-Miguel, Mario and Jackson, Daniel},
  title   = {{axR}: Interfacing and Retrieving Data from Accelerometer Devices},
  year    = {2026},
  version = {0.1.3},
  doi     = {10.5281/zenodo.21393892},
  url     = {https://github.com/circadia-bio/axR}
}

⌚️ zeitR — wrist actigraphy analysis and circadian metrics
🪉 mrpheus — raw physiological signal analysis (PSG/EEG)
🔄 syncR — ecosystem integrator, pulls data into a unified participant database
🔬 circadia-bio — the Circadia Lab GitHub organisation

⛏️ axR

📖 What is axR?

✨ Features

🗂️ Project Structure

🚀 Getting Started

Prerequisites

Installation

Vignette

📦 Dependencies

👥 Authors

📄 Citation

📄 Licence

⛏️ axR

📖 What is axR?

✨ Features

🗂️ Project Structure

🚀 Getting Started

Prerequisites

Installation

Vignette

📦 Dependencies

👥 Authors

📄 Citation

🤝 Related Tools

📄 Licence