# Gateway

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
manufacturer data company_id `0xffff` as defined in the firmware specification. 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:**
```json
{
  "timestamp": "2026-04-08T07:53:28Z",
  "temp": 25.37,
  "humidity": 44,
  "co2_ppm": 400,
  "window_open": false,
  "battery": 85	
}
```

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:

```json
{
  "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

```bash
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 before running:

```bash
mkdir -p ~/secrets
nano ~/secrets/mqtt.env
chmod 600 ~/secrets/mqtt.env
```

Add the following content to the file:
MQTT_PASSWORD=your_password

Warning: do not use echo to write the password — it will remain
in your bash history. Always use a text editor like nano.

```bash
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:

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

Check status and logs:

```bash
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**
```bash
ssh pi@raspberrypi.local
```

**2. Update the system**
```bash
sudo apt update && sudo apt upgrade -y
```

**3. Check and enable Bluetooth**
```bash
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)
```bash
sudo apt install -y mosquitto mosquitto-clients
```

**5. Clone the repository**
```bash
git clone https://github.com/PI-E2EEDA/Plein-de-eeeeeeeeee-project.git
cd Plein-de-eeeeeeeeee-project/gateway
```

**6. Create Python environment**
```bash
python3 -m venv venv
source venv/bin/activate
pip install -r requirements.txt
```

**7. Create configuration file**
```bash
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**
```bash
mkdir -p ~/secrets
nano ~/secrets/mqtt.env
chmod 600 ~/secrets/mqtt.env
```
Add the following content to the file:
MQTT_PASSWORD=your_password

**9. Install the systemd service**
Warning: the paths in gateway.service are hardcoded for the default
pi user on Raspberry Pi OS. If you use a different username, update
User, WorkingDirectory and ExecStart before copying the file.

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

**10. Verify everything works**
```bash
sudo systemctl status gateway
# Expected: "active (running)"
sudo journalctl -u gateway -f
# Expected: Gateway ID, MQTT connected, BLE scan started
```

**11. Test automatic restart**
```bash
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 (`Successfully connected to MQTT broker`)
- [ ] Battery level included in published payload
- [ ] 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.