# MQTT Configuration

 This project can publish weather and public transport data to an MQTT broker.
 To enable MQTT, follow these steps:

 ## 1. Install dependencies
 Ensure you have Rust and Cargo installed. The MQTT support uses the Paho MQTT client crate.
 Run:
 ```bash
 cargo update
 ```

 ## 2. Set the MQTT_BROKER environment variable
 Before running the client, define `MQTT_BROKER` to your broker address.
 - Without URI scheme (defaults to TCP):
   ```bash
   export MQTT_BROKER=localhost:1883
   ```
 - With URI scheme:
   ```bash
   export MQTT_BROKER=tcp://broker.example.com:1883
   ```

 ## 3. Run the LED board client
 Pass the LED board IP address as the only argument:
 ```bash
 export MQTT_BROKER=localhost:1883
 cargo run --bin ledboard_client -- 192.168.1.50
 ```

 ## Topics and Payloads
 The client publishes two topics:

 ### weather
 JSON payload with fields:
 - `dt`: timestamp (Unix seconds)
 - `temp`: temperature in °C
 - `weather`: object with `main`, `description`, `icon`
 - `rain`: rain volume in last 3h (optional)
 - `pop`: probability of precipitation
 - `wind`: object with `speed`, `deg`, `gust`

 ### straba
 JSON payload with fields:
 - `outbound_station`: name of outbound station
 - `outbound_diff`: seconds until outbound departure
 - `inbound_station`: name of inbound station
 - `inbound_diff`: seconds until inbound departure

 ## Customization
 You can adjust MQTT topics, QoS, and message formats in `client/bin/src/main.rs` under the `publish_to_mqtt` function.