Read CO2, temperature, humidity, pressure, and battery from an Aranet4 sensor over Bluetooth LE and log to a local SQLite database. Visualise with Grafana.

Designed to run on a Raspberry Pi via crontab.

• Raspberry Pi (tested on Pi 4 / Pi 5) with Bluetooth
• Raspberry Pi OS (Bookworm or later)
• Bluetooth enabled and running (sudo systemctl status bluetooth)
• Python 3.9+ (pre-installed on Bookworm)
• uv (curl -LsSf https://astral.sh/uv/install.sh | sh)
• Grafana + SQLite datasource plugin (installed in steps 8-9 below)
• An Aranet4 sensor within Bluetooth range
• Smart Home integrations enabled in the Aranet Home phone app (device settings) — required for BLE data access

All shell commands below work in both bash and fish.

git clone https://github.com/12ian34/aranet4-dash.git
cd aranet4-dash
uv sync

That's it — uv sync creates the venv and installs dependencies from pyproject.toml.

Make sure the Aranet4 is nearby.

uv run aranetctl --scan

Look for your device in the output:

=======================================
  Name:     Aranet4 0A3D9
  Address:  AA:BB:CC:DD:EE:FF
  RSSI:     -83 dBm
---------------------------------------
  CO2:            593 ppm
  Temperature:    19.0 °C
  ...

Note the MAC address. If no readings appear, make sure Smart Home integrations is enabled in the Aranet Home app.

sudo mkdir -p /var/lib/aranet4-dash
sudo chown $USER:grafana /var/lib/aranet4-dash
chmod 750 /var/lib/aranet4-dash

This keeps the DB outside your home directory so Grafana (grafana user) can read it via group permissions without exposing anything else.

Copy the example and fill in your values:

cp .env.example .env
nano .env

ARANET_MAC=AA:BB:CC:DD:EE:FF
DB_PATH=/var/lib/aranet4-dash/aranet.db
POLL_INTERVAL=60

• ARANET_MAC — the MAC address from step 2
• DB_PATH — where to store the SQLite database
• POLL_INTERVAL — seconds between readings in daemon mode (default 60, not used by crontab)

cd ~/dev/aranet4-dash    # or wherever you cloned the repo
uv run aranet_logger.py --single

You should see output like:

2026-02-09 12:00:00 INFO Scanning for Aranet4 (AA:BB:CC:DD:EE:FF)...
2026-02-09 12:00:10 INFO CO2=593 ppm  Temp=19.0°C  Humidity=56%  Pressure=998.2 hPa  Battery=96%
2026-02-09 12:00:10 INFO Reading saved to database

sqlite3 /var/lib/aranet4-dash/aranet.db

SELECT * FROM aranet_readings ORDER BY timestamp DESC LIMIT 5;
.quit

Cron always uses /bin/sh, so fish vs bash doesn't matter here.

crontab -e

Add these lines to poll every minute:

PATH=$HOME/.local/bin:/usr/local/bin:/usr/bin:/bin

* * * * * cd $HOME/dev/aranet4-dash && uv run aranet_logger.py --single >> $HOME/dev/aranet4-dash/cron.log 2>&1

The PATH line ensures cron can find uv. Save and exit, then verify:

crontab -l

Check it's working after a few minutes:

tail -f ~/dev/aranet4-dash/cron.log

sudo apt-get install -y apt-transport-https software-properties-common
sudo mkdir -p /etc/apt/keyrings/
wget -q -O - https://apt.grafana.com/gpg.key | gpg --dearmor | sudo tee /etc/apt/keyrings/grafana.gpg > /dev/null
echo "deb [signed-by=/etc/apt/keyrings/grafana.gpg] https://apt.grafana.com stable main" | sudo tee /etc/apt/sources.list.d/grafana.list
sudo apt-get update
sudo apt-get install -y grafana

Start and enable:

sudo systemctl daemon-reload
sudo systemctl enable --now grafana-server

Grafana is now running at http://<pi-ip>:3000. Default login is admin / admin.

sudo grafana-cli plugins install frser-sqlite-datasource
sudo systemctl restart grafana-server

1. Open Grafana at http://<pi-ip>:3000
2. Go to Connections > Data sources > Add data source
3. Search for SQLite
4. Set the path to:

   /var/lib/aranet4-dash/aranet.db
   

5. Click Save & test — should say "Data source is working"

A pre-built dashboard JSON is included in the repo at grafana/dashboard.json.

1. In Grafana, go to Dashboards > New > Import
2. Click Upload JSON file and select grafana/dashboard.json from the repo
3. Click Import

The dashboard includes:

• Bar gauge — latest reading for CO2, Temperature, Humidity, Pressure, Battery with colour-coded thresholds, plus a "Last Updated" relative timestamp
• CO2 time series — with green/yellow/red threshold bands at 800/1000 ppm
• Temperature time series — blue line with comfort-zone threshold bands, 10-35 C range
• Humidity time series — blue line with threshold bands, 0-100% range
• Pressure time series — blue line, 950-1050 hPa range

Note: The timestamp column stores SQLite datetime strings, but the SQLite datasource plugin needs numeric Unix epoch values. Time series queries convert with CAST(strftime('%s', timestamp) AS INTEGER) (seconds). The bar gauge "Last Updated" field uses * 1000 (milliseconds) so Grafana's dateTimeFromNow unit can display relative time like "5 min ago".

CREATE TABLE IF NOT EXISTS aranet_readings (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    timestamp DATETIME DEFAULT CURRENT_TIMESTAMP,
    co2_ppm INTEGER,
    temperature_c REAL,
    humidity_percent REAL,
    pressure_hpa REAL,
    battery_percent INTEGER
);

CREATE INDEX IF NOT EXISTS idx_timestamp ON aranet_readings(timestamp);

The database grows at roughly 1 row per reading (~100 bytes). At 1-minute intervals that's about 15 MB/year.

To manually compact:

sqlite3 /var/lib/aranet4-dash/aranet.db "VACUUM;"

To delete old data (e.g. older than 1 year):

sqlite3 /var/lib/aranet4-dash/aranet.db "DELETE FROM aranet_readings WHERE timestamp < datetime('now', '-1 year');"
sqlite3 /var/lib/aranet4-dash/aranet.db "VACUUM;"

• Make sure the Aranet4 is within Bluetooth range
• Check Bluetooth is up: sudo systemctl status bluetooth
• Restart Bluetooth: sudo systemctl restart bluetooth
• Make sure the MAC address in .env is correct
• Try uv run aranetctl --scan to verify the device is visible

• Smart Home integrations must be enabled in the Aranet Home phone app — without it the device won't broadcast readings in BLE advertisements

# Check cron is running
sudo systemctl status cron

# Check the log
tail -20 ~/dev/aranet4-dash/cron.log

# Make sure uv is on PATH
which uv

The DB lives in /var/lib/aranet4-dash/ which should be owned by <your-user>:grafana. Check permissions:

ls -la /var/lib/aranet4-dash/
# Should show: drwxr-x--- <user> grafana  (directory)
# and:        -rw-r----- <user> grafana  (aranet.db)

Fix if needed:

sudo chown $USER:grafana /var/lib/aranet4-dash /var/lib/aranet4-dash/aranet.db
chmod 750 /var/lib/aranet4-dash
chmod 640 /var/lib/aranet4-dash/aranet.db