BME680 WiFi Sensor Firmware

This repository contains the firmware for an ESP32-based environmental sensor utilizing the Bosch BME680 sensor. The device connects to a WiFi network and publishes sensor data (temperature, humidity, pressure, and gas resistance) to an MQTT broker. It also subscribes to a command topic to receive instructions.

Features

Environmental Sensing: Accurately measures ambient temperature, relative humidity, barometric pressure, and volatile organic compounds (VOCs) via the BME680 sensor.
WiFi Connectivity: Connects to your local WiFi network using saved credentials, ensuring seamless integration into your smart home or IoT setup.
MQTT Data Publishing: Publishes real-time sensor readings to a configurable MQTT broker. Data is formatted as JSON for easy parsing by other applications or dashboards.
MQTT Command Subscription: Subscribes to a specific MQTT topic to receive commands, allowing for remote control or configuration updates (e.g., changing sampling rate, triggering actions).
Real-time Sensor Readings: Provides continuous updates of environmental parameters, enabling dynamic monitoring and automation.
Configurable Sampling Rate: The frequency of sensor readings and MQTT publishing can be adjusted to optimize power consumption and data granularity.
Error Handling & Reconnection: Robust handling for WiFi and MQTT connection errors, including automatic reconnection attempts to maintain continuous operation.

Hardware Requirements

To build and run this project, you will need the following hardware components:

ESP32 Development Board: Any standard ESP32 development board (e.g., ESP32-DevKitC, NodeMCU-32S) with sufficient GPIO pins for I2C communication.
BME680 Sensor Module: A BME680 breakout board. Ensure it has pull-up resistors on the I2C lines if your development board does not provide them.
Power Supply: A 5V power supply for the ESP32 board (e.g., USB cable, external power adapter).
Connecting Wires: Jumper wires to connect the BME680 sensor to the ESP32 board via I2C.

Wiring Diagram (Example)

BME680 Pin	ESP32 Pin (Typical)
VCC	3.3V
GND	GND
SDA	GPIO 21
SCL	GPIO 22

Note: GPIO pins for SDA/SCL might vary depending on your ESP32 board. Refer to your board’s pinout diagram.

Software Dependencies

This project is built using the ESP-IDF framework. Ensure you have the following installed:

ESP-IDF Framework: Version 4.x or newer is recommended. Follow the official ESP-IDF Programming Guide for installation instructions.
BME680 Driver: This project integrates a BME680 driver. Ensure it’s compatible with your ESP-IDF version.
MQTT Client Library: The ESP-IDF includes an MQTT client component (esp-mqtt).

Getting Started

Follow these steps to get your BME680 WiFi Sensor up and running:

Clone this repository:

git clone https://github.com/manupawickramasinghe/bme680-wifi-sensor-firmware.git
cd bme680-wifi-sensor-firmware

Install ESP-IDF: If you haven’t already, install the ESP-IDF framework by following the instructions in the ESP-IDF Programming Guide. This includes setting up the toolchain and environment variables.
Configure WiFi and MQTT credentials: Navigate to the project directory and run the ESP-IDF configuration tool:
```
idf.py menuconfig
```
In menuconfig:
- Go to Component config -> Wi-Fi and configure your WiFi SSID and Password.
- Go to Component config -> MQTT and configure your MQTT broker URI (e.g., mqtt://broker.hivemq.com:1883).
- You might also find options to configure sensor-specific parameters or MQTT topics under custom component configurations if added.
Build the firmware:
```
idf.py build
```
Flash the firmware to your ESP32: Connect your ESP32 board to your computer via USB. Ensure you know the serial port name (e.g., /dev/ttyUSB0 on Linux/macOS, COMx on Windows).
```
idf.py -p <PORT> flash
```
Replace <PORT> with your ESP32’s serial port.
Monitor sensor data via MQTT: After flashing, the ESP32 will connect to WiFi and start publishing data. You can monitor the serial output for logs:
```
idf.py -p <PORT> monitor
```
To view the MQTT data, use an MQTT client (e.g., MQTT Explorer, Mosquitto client) and subscribe to the configured topics.

Configuration

The project’s configuration is primarily handled via idf.py menuconfig. Key parameters include:

WiFi Credentials: SSID and password for your network.
MQTT Broker URI: The address of your MQTT broker (e.g., mqtt://broker.hivemq.com:1883).
MQTT Topics:
- Publish Topic: /zektopic/sensor/bme680/data (default, can be changed in code)
- Subscribe Topic: /zektopic/sensor/bme680/command (default, can be changed in code)
Sensor Reading Interval: The delay between sensor readings and data publishing (e.g., 5 seconds). This is typically defined in main.c or a configuration header.

MQTT Topics and Data Format

Published Data Topic

The sensor publishes data to /zektopic/sensor/bme680/data (or a similar configured topic). The data is sent as a JSON string.

Example JSON Payload:

{
  "temperature_c": 25.50,
  "humidity_percent": 60.25,
  "pressure_hpa": 1012.34,
  "gas_resistance_ohm": 150000.00
}

Subscribed Command Topic

The device subscribes to /zektopic/sensor/bme680/command to receive commands. The expected command format is a simple string.

Example Command Payload:

REBOOT

Note: The current firmware might only log received commands. Extend mqtt_event_handler to implement specific actions based on commands.

Troubleshooting

“Host is unreachable” / DNS errors:
- Ensure your ESP32 has a stable WiFi connection and receives an IP address.
- Verify your MQTT broker URI is correct, including the port.
- Try using the IP address of the MQTT broker instead of the hostname (e.g., mqtt://91.121.93.94:1883 for test.mosquitto.org).
- Check your network’s DNS settings.
“Failed to open a new connection”:
- The MQTT broker might be down or unreachable from your network.
- Firewall issues on the broker side or your local network.
- Incorrect port number in the MQTT URI.
No data published:
- Verify the MQTT client is connected (check serial logs for MQTT_EVENT_CONNECTED).
- Ensure the publish topic is correct and your MQTT client is subscribed to it.
- Check sensor initialization and reading functions for errors.
BME680 reading 0.00 Ohm for gas resistance:
- The BME680 gas sensor requires a burn-in period (typically 20-30 minutes) after power-on to stabilize. Initial readings might be inaccurate or zero.
- Ensure the BME680 driver is correctly initialized and calibrated.

Contributing

Contributions are welcome! If you have suggestions for improvements, bug fixes, or new features, please open an issue or submit a pull request.

License

This project is licensed under the MIT License - see the LICENSE file for details.