BLE-to-MQTT gateway running on a Raspberry Pi 4. Listens to Nordic Thingy:52 sensor nodes broadcasting environmental data over BLE and publishes it to a remote MQTT broker on each reception.

Architecture

[Thingy #1] ──┐
[Thingy #2] ──┼──(BLE)──> [Raspberry Pi / gateway.py] ──(MQTT)──> [Broker]
[Thingy #n] ──┘

The gateway listens passively to BLE advertising packets and filters on the Nordic Configuration service UUID (ef680100). Each received packet is decoded following the firmware key/value specification and published immediately to the MQTT broker.

MQTT interface

Topic: {gateway_id}/{thingy_mac}/update

Example: gateway_lausanne_01/C4:64:02:60:D9:16/update

Payload:

{
  "timestamp": "2026-04-08T07:53:28Z",
  "temp": 25.37,
  "humidity": 44,
  "co2_ppm": 400,
  "window_open": false
}

Fields are included only if present in the advertising packet. Values outside the valid range defined in the firmware specification indicate a failed sensor reading and are discarded.

Configuration

A config.example.json template is provided. Copy it to config.json and edit the values before running:

{
  "gateway_id": "gateway_example",
  "mqtt": {
    "broker": "mqtt.example.com",
    "port": 8883,
    "username": "your_username",
    "tls": true
  },
  "ble": {
    "service_uuid": "ef680100-9b35-4933-9b10-52ffa9740042"
  }
}

Each deployed gateway has its own config.json. The source code remains identical across all deployments.

Installation

sudo apt install -y mosquitto mosquitto-clients
sudo rfkill unblock bluetooth
sudo systemctl enable bluetooth
sudo bluetoothctl power on

python3 -m venv venv
source venv/bin/activate
pip install -r requirements.txt

cp config.example.json config.json
# Edit config.json with your gateway_id, broker address and username

Usage

Set the MQTT password as an environment variable before running:

mkdir -p ~/secrets
echo "MQTT_PASSWORD=your_password" > ~/secrets/mqtt.env
chmod 600 ~/secrets/mqtt.env
export MQTT_PASSWORD="your_password"
source venv/bin/activate
python gateway.py

The password is never stored in config files or source code.

Systemd service

To run the gateway automatically on boot:

sudo cp gateway.service /etc/systemd/system/
sudo systemctl daemon-reload
sudo systemctl enable gateway
sudo systemctl start gateway

Check status and logs:

sudo systemctl status gateway
sudo journalctl -u gateway -f

Deployment checklist

Follow these steps to deploy the gateway on a new Raspberry Pi.

1. Connect to the Pi

ssh pi@raspberrypi.local

2. Update the system

sudo apt update && sudo apt upgrade -y

3. Check and enable Bluetooth

sudo rfkill unblock bluetooth
sudo systemctl enable bluetooth
sudo systemctl start bluetooth
sudo bluetoothctl power on
# Expected: "Changing power on succeeded"

4. Install Mosquitto (for local testing)

sudo apt install -y mosquitto mosquitto-clients

5. Clone the repository

git clone https://github.com/PI-E2EEDA/Plein-de-eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee-project.git
cd Plein-de-eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee-project/gateway

6. Create Python environment

python3 -m venv venv
source venv/bin/activate
pip install -r requirements.txt

7. Create configuration file

cp config.example.json config.json
nano config.json
# Set a unique gateway_id for this Pi
# Example: "gateway_id": "gateway_fribourg_01"

8. Create the secret file

mkdir -p ~/secrets
echo "MQTT_PASSWORD=your_password" > ~/secrets/mqtt.env
chmod 600 ~/secrets/mqtt.env

9. Install the systemd service

sudo cp gateway.service /etc/systemd/system/
sudo systemctl daemon-reload
sudo systemctl enable gateway
sudo systemctl start gateway

10. Verify everything works

sudo systemctl status gateway
# Expected: "active (running)"
sudo journalctl -u gateway -f
# Expected: Gateway ID, MQTT connected, BLE scan started

11. Test automatic restart

sudo reboot
# After reboot, reconnect via SSH
sudo systemctl status gateway
# Expected: "active (running)" without any manual intervention

Validation checklist

active (running) in systemctl status
Correct gateway ID in logs
MQTT connection established (MQTT client connected)
TLS enabled (TLS enabled)
BLE scan started (BLE scan started)
Thingy:52 nodes detected in logs after power on
Service restarts automatically after reboot

Notes on the CO2 sensor

The Thingy:52 embeds a CCS811 sensor which measures eCO2 — an estimated CO2 value derived from volatile organic compound (VOC) levels rather than a direct CO2 measurement. Values should be interpreted as indicative trends. The sensor requires a burn-in period of 48 hours on first use before readings stabilize.