Arduino Soft-Sensor MQTT Device Code

This project demonstrates an Arduino-based soft-sensor device that reads environmental data (temperature, pH, and electrical conductivity) and publishes it to an MQTT server over NB-IoT and GPRS networks.

You can find more information about Kafka-ML and the methodology in the following open-access publication

If you use this code or the methodology in your research, please cite one of the following jobs:

@article{chaves2024softsensor,
    title={A soft sensor open-source methodology for inexpensive monitoring of water quality: a case study of NO3 concentrations},
    author={Chaves, A.J., et al.},
    journal={TBD},
    year={2024},
    volume={-},
    pages={-},
    doi={-}
}

@incollection{chaves2023methodology,
  title={A methodology for the development of soft sensors with Kafka-ML},
  author={Chaves, Antonio Jes{\'u}s and Mart{\'\i}n, Cristian and Torres, Luis Llopis and Soler, Enrique and D{\'\i}az, Manuel},
  booktitle={Data Analytics for Internet of Things Infrastructure},
  pages={307--324},
  year={2023},
  publisher={Springer}
}

Images

Hardware setup

Deployment example

Table of Contents

• Arduino Soft-Sensor MQTT Device Code
  • Images
    • Hardware setup
    • Deployment example
  • Table of Contents
  • Features
  • Hardware Used
  • Software Requirements
  • Wiring Diagram
  • Installation
  • Usage
  • Code Overview
    • setup()
    • initializeNB_GPRS()
    • reconnectMQTT()
    • read_temperature()
    • read_sensor_data()
    • loop()
    • readSerial(char result[])
  • Contributing
  • License

Features

• Reads temperature, pH, and electrical conductivity (EC) data.
• Publishes sensor data to an MQTT server.
• Utilizes NB-IoT and GPRS for communication.
• Low power consumption with sleep mode.

Hardware Used

• Arduino MKR NB 1500
• DFRobot pH sensor (DFR0300)
• DFRobot EC sensor (SEN0169-V2)
• Adafruit Temperature sensor (642-DS18B20)
• Multiprotocol Antenna (FXUB63.07.0150C)
• SIM card with NB-IoT and GPRS support

Software Requirements

• Arduino IDE
• MKRNB Library
• MQTT Library
• OneWire Library
• DallasTemperature Library
• MKR_DFRobot_EC Library
• MKR_DFRobot_PH Library
• ArduinoLowPower Library

Wiring Diagram

Connect the sensors to the Arduino MKR board as follows:

• pH Sensor: Analog pin A4
• EC Sensor: Analog pin A2
• Temperature Sensor: Analog pin A6

Installation

1. Clone the repository:

   git clone https://github.com/ertis-research/arduino-softsensor-kafkaml.git

2. Open the project in Arduino IDE:

   arduino arduino-softsensor-kafkaml/NB_SendDataKafkaML.ino

3. Install the required libraries via the Arduino Library Manager:

   • MKRNB
   • MQTT
   • OneWire
   • DallasTemperature
   • DFRobot_EC (you may need to modify these libraries to work with the MKR NB 1500 board, as it works at 3.3v instead of 5v)
   • DFRobot_PH (you may need to modify these libraries to work with the MKR NB 1500 board, as it works at 3.3v instead of 5v)
   • ArduinoLowPower

4. Update the secrets.h file with your credentials:

   #define SECRET_SIM_PINNUMBER "your_sim_pin"
   #define SECRET_SIM_APN "your_apn"
   #define MQTT_SERVER "your_mqtt_server"
   #define MQTT_PORT your_mqtt_port
   #define MQTT_USER "your_mqtt_username"
   #define MQTT_PASSWORD "your_mqtt_password"

Usage

1. Upload the code to your Arduino MKR board.
2. Open the Serial Monitor at 115200 baud rate to observe the debug messages.
3. Monitor the sensor data being published to your MQTT server.

Code Overview

setup()

Initializes serial communication and sets up the MQTT client.

initializeNB_GPRS()

Attempts to connect to the NB-IoT and GPRS network until a connection is established.

reconnectMQTT()

Attempts to connect to the MQTT server until a connection is established.

read_temperature()

Reads and returns the temperature in Celsius from the DallasTemperature sensor.

read_sensor_data()

Reads temperature, pH, and EC sensor data, compensates pH and EC values with the temperature, performs sensor calibration if needed, and returns the formatted sensor data.

loop()

Main loop function that initializes the network connection, connects to the MQTT server, reads sensor data, publishes it to the MQTT topic, and then puts the device to sleep.

readSerial(char result[])

Reads a line from the serial input into the provided result array. Used for calibration commands.

Contributing

Contributions are welcome! Please fork the repository and submit a pull request for any enhancements or bug fixes.

License

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

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Happy Coding! 🚀