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Published May 22, 2025

Eco-Smart AQ/AG Mesh Node

Self-sustained smart aquaculture/agriculture node powered by renewable energy, with mesh network & advanced sensors for real-time monitoring

AdvancedWork in progress4 days73

Things used in this project

Hardware components

Nordic Semiconductor nRF9151 DK

DFRobot Water Turbine Generator (5VDC)

The quantity to be increased or cascaded based on the current requirements during development

TP4056 1A Li-ion lithium Battery Charging Module With Current Protection – Type C

*subjective to change during development

DFRobot Gravity: 7/24 Industrial Analog pH Meter Kit

DFRobot Gravity: Lab Grade Analog EC / Electrical Conductivity Sensor Kit

DFRobot Gravity: Analog Dissolved Oxygen / DO Sensor Meter Kit

DFRobot Gravity: Industrial Stainless Steel Submersible Pressure Level Sensor(0~5m)

DFRobot Gravity: Analog TDS Sensor

DFRobot Gravity: Analog Turbidity Sensor for Arduino

DFRobot Gravity: Analog Industrial ORP Sensor

DFRobot Waterproof DS18B20 Digital Temperature Sensor

Software apps and online services

Autodesk Fusion

Nordic Semiconductor nRF Connect SDK

Zephyr Project Zephyr RTOS

PCBWay 3D Printing Service

Hand tools and fabrication machines

Soldering iron (generic)

3D Printer (generic)

Story

Idea

The idea behind this project stems from the growing need for sustainable and efficient solutions in the fields of aquaculture and agriculture, driven by an increasing global demand for food production and environmental conservation. As we look toward the future, it becomes evident that traditional methods of farming and aquaculture are no longer sufficient to meet the challenges of climate change, resource depletion, and population growth.

In response to these challenges, this project aims to create a smart aquaculture node device that can monitor and manage water quality, environmental factors, and overall health of the aquaculture ecosystem in real-time. The system consists of two main units: one installed in the pond or aquaculture area, where various probes and sensors continuously collect data about critical parameters such as dissolved oxygen, pH levels, ammonia, nitrate, temperature, and more. The second unit is located on land, where it receives this data and transmits it to a central control device for further analysis and decision-making (although the control device is not part of the current scope). In large-scale aquaculture fields, the system can scale to support hundreds or even thousands of these node devices, allowing for comprehensive monitoring across vast areas, ensuring optimal conditions for aquaculture management.

A key feature of this system is the nRF9151DK, which supports mesh networking using DECT NR+ technology, making it an ideal solution for this project. The DECT NR+ (New Radio DECT) standard, a next-generation wireless communication technology, provides high-quality, low-latency communication over long distances, making it perfect for remote aquaculture systems. With its mesh networking capability, the system can support seamless communication between hundreds or thousands of nodes deployed across large aquaculture fields, ensuring reliable data transmission even in challenging environments with limited infrastructure. The mesh network ensures that each device communicates not only directly with the main node but also with other neighboring devices, creating a self-healing network that can adapt to dynamic changes like node failures or environmental interference. This makes the system robust and scalable, providing consistent and reliable data, regardless of the size or complexity of the deployment. Additionally, optional protocols like Bluetooth Mesh, Thread, and Zigbee provide flexibility for integrating the system into existing setups.

The system is designed to be eco-friendly and self-sustaining. Power is drawn from renewable sources like turbines that harness energy from the circulating water in the aquaculture system. In case of insufficient power, multiple turbines are cascaded to ensure continuous energy generation. A 2500 mAh battery or larger stores the collected energy, providing reliable power for the system, making it truly self-sustaining and environmentally conscious.

This project not only addresses the urgent need for monitoring and managing aquaculture systems but also presents a model that can be adapted to agricultural settings. By changing the sensor probes, the system can be used to measure critical soil parameters, further enhancing its versatility and scope. For agricultural applications, the system can be powered by solar panels instead of turbines, effectively harnessing energy from sunlight, whether it’s from open fields or the controlled environment of greenhouses. Ultimately, the goal is to create a solution that helps optimize aquaculture and agriculture practices while minimizing environmental impact, ensuring a more sustainable future for both industries.

The nRF9151DK includes key features like SIM card support, LTE connectivity, and GNSS capabilities, all of which play a crucial role in this project. With LTE-M and NB-IoT support, the system can send sensor data over LTE networks, enabling remote monitoring and control from far-off locations. This allows operators or managers to access real-time data from the aquaculture farms or agricultural fields and make informed decisions without being on-site. The GNSS feature provides accurate location tracking for each node, which is particularly useful in large-scale deployments across vast aquaculture fields, ensuring precise positioning for the devices and aiding in geo-tagging of data. In the future, the NTN (Non-Terrestrial Networks) update for the nRF9151DK will enable connectivity in even more remote areas, where traditional cellular or Wi-Fi networks may not be available. This capability could provide global coverage, making the system even more adaptable for monitoring in isolated environments like offshore aquaculture farms or far-flung agricultural zones.

Prototype System Design

Hardware Design

The hardware design of the prototype focuses on leveraging the capabilities of the nRF9151DK and integrating essential sensor modules and power systems to ensure seamless functionality. Below are the key components and their interconnections:

Power Management:

A TP4056 1A Li-ion Lithium Battery Charging Module is utilized to charge a 2500mAh or larger Li-ion battery, which serves as the primary power source for the nRF9151DK.
The input to the TP4056 module is derived from turbines in the Recirculating Aquaculture System (RAS), ensuring eco-friendly power generation through the water's circulation. Multiple turbines may be cascaded to generate sufficient power if required. Water circulation is essential in all aquaculture systems, although the frequency of circulation varies.
An external jack provides the flexibility to connect either the turbine-generated input or a conventional DC power source for backup.

Sensor Integration:

A variety of sensors are connected to the nRF9151DK to monitor critical parameters of the aquaculture environment, such as:

pH Monitoring: A Gravity: 7/24 Industrial Analog pH Meter Kit probe is interfaced via the analog pin to provide continuous pH level updates.
TDS (Total Dissolved Solids): The Gravity: Analog TDS Sensor/Meter V1.0 is connected to measure the concentration of dissolved solids in water, providing a clear indicator of water quality.
Turbidity: The Gravity: Analog Turbidity Sensor monitors the clarity of water by measuring the amount of suspended particles, helping to detect contamination or sediment levels.
Dissolved Oxygen: The Gravity: Analog Dissolved Oxygen Sensor Kit measures the oxygen concentration in water, a critical parameter for maintaining aquatic life.
Pressure: The Gravity: Water Pressure Sensor tracks pressure variations in the water system, aiding in flow management and system optimization.
ORP (Oxidation-Reduction Potential): The Gravity: ORP Sensor Kit monitors the water’s oxidative properties, which can indicate the level of organic contamination.
Temperature: The Gravity: Waterproof DS18B20 Temperature Sensor provides accurate temperature readings, crucial for maintaining ideal aquaculture conditions.
Electrical Conductivity (Salinity): The Gravity: Analog Electrical Conductivity Sensor measures the salinity of the water, which is vital for species-specific aquaculture requirements.

Communication and Networking:

The nRF9151DK acts as the main communication hub, utilizing its DECT NR+ mesh networking capability to transmit data from multiple node devices across the aquaculture field to a centralized control system.
Optional communication protocols such as Bluetooth Mesh, Thread, and Zigbee are included to facilitate integration with existing setups if needed.

Data Transmission and Location Tracking:

The LTE-M and NB-IoT capabilities of the nRF9151DK allow for real-time data transmission to remote monitoring stations, while the built-in GNSS module provides precise location tracking of individual nodes.
Future incorporation of NTN (Non-Terrestrial Networks) will enable connectivity in remote or network-scarce areas, further enhancing the system's reliability.

This hardware architecture ensures a self-sustaining, eco-friendly system that collects, processes, and transmits critical environmental data for aquaculture, with provisions for power redundancy and scalability for large-scale deployments.

1 / 5 • System Architecture

Mechanical Design

The mechanical architecture of the prototype system is designed to accommodate two distinct units:

1. Land Unit

This unit houses the control boards, including the nRF9151DK, and other critical electronics.
The enclosure is designed to be compact and robust, ensuring protection against environmental factors like dust and moisture (to the possible extent in prototype).
The mechanical enclosure has a single opening designed for both sensor cables and power cables. This reduces the risk of water or dust ingress, while maintaining ease of connectivity and power management. These cables are grouped into a wire harness or twisted cable assembly, ensuring a neat and organized setup. The wire harness splits into two branches:1. Sensor Connection: This branch connects to the various sensor probes submerged in the aquaculture water body.2.Power Connection: This branch terminates in a single jack, allowing for flexible power input. The jack is designed to support either a direct DC power connection or input from turbines, depending on the power source availability.

2. Water Unit

This unit incorporates sensor probes and sensing elements, which are submerged in the aquaculture water body to measure various parameters.
The enclosure is designed to ensure direct water contact for the probes while providing adequate protection against physical damage caused by aquatic life.
To safeguard the sensors, protective grills or mesh covers designs are incorporated, ensuring uninterrupted functionality while preventing damage from fish or debris.
Sensor placement within the water unit is carefully planned to avoid the need for an external water level sensor, as the water level can be inferred from the sensors' position.

Material, Prototyping & Design Specification:

Both the land and water units are proposed to be made from ABS plastic for its durability, lightweight nature, and resistance to environmental conditions (to the possible extent).
Prototyping of these enclosures is done using a 3D printer, allowing for cost-effective and customizable designs.
Both units are designed with maximum compactness to ensure ease of installation and maintenance. The modular design allows for simple assembly, disassembly, and replacement of components, which is especially important during prototype testing and iterations.

The mechanical design ensures the prototype's functionality, durability, and adaptability, providing a strong foundation for transitioning to a full-fledged product design in the future.

1 / 6 • Land Unit Enclosure Design

1 / 3

End Product Integration

The final design integrates all individual modules—such as the sensor modules, nRF9151DK, and power management circuits—into a single compact PCB. The TP4056 module will be replaced by the TI BQ25792, which supports dual power input, enabling simultaneous connection of both DC power and turbine power. The system's enclosure will be designed with a mechanical provision to accommodate these connections seamlessly. The integration of the TI BQ25792 IC enhances the monitoring of device health and battery performance. This feature will provide accurate real-time feedback on battery status, such as charge percentage and health indicators, enabling remote monitoring and timely interventions if required. These parameters will be transmitted along with the aquaculture farm data, ensuring comprehensive visibility into the system’s operational state.

The device will be designed to support direct plug-and-play sensor integration, allowing users to connect specific sensor modules based on their monitoring requirements. For example, if monitoring a particular parameter is critical for a specific aquaculture species, users can directly plug in the corresponding sensor module while omitting less relevant ones. This flexibility makes the device highly versatile and adaptable to different use cases.

The land unit enclosure material will be upgraded from ABS plastic to a transparent material, making the internal vibrant PCB design visible, enhancing the aesthetic appeal. Programmable LED indicators will also be added to indicate parameters like network availability, power status, and various other status indicators A dedicated power LED will be included for quick visual reference of the power status of the board.

The device will be designed to be more compact, ensuring easy deployment in aquaculture and agriculture environments. To ensure durability in harsh environmental conditions typical of these areas, the enclosure will be designed to meet IP68/IP69 standards, offering waterproof and dustproof protection.

Furthermore, the hardware architecture and schematics of the proposed end product have been attached to provide a detailed view of the design and system integration. This ensures a robust, eco-friendly, and self-sustained monitoring solution for both aquaculture and agriculture applications.

Code

/******************************************************************************
 * Eco-Smart AQ/AG Mesh Node
 * 
 * Features:
 * - Air Quality (BME680: CO2, TVOC, Temp, Humidity, Pressure)
 * - Soil Monitoring (Moisture, NPK, pH)
 * - Water Quality (pH, Dissolved Oxygen, Turbidity, Temp)
 * - LoRaWAN + Mesh Networking
 * - Solar-Powered Low-Energy Operation
 ******************************************************************************/

#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include "boards.h"
#include "timer.h"
#include "bme680.h"
#include "ads1115.h"
#include "ds18b20.h"    // Water temp sensor
#include "sensor.h"
#include "low_power.h"
#include "lorawan.h"
#include "mesh.h"
#include "solar.h"

// Configuration
#include "config.h"

// Global variables
static TimerEvent_t appTimer;
static bool sleepMode = false;
static sensor_data_t sensorData;

// Function prototypes
static void init_sensors(void);
static void read_sensors(void);
static void process_sensor_data(void);
static void send_data(void);
static void enter_sleep_mode(void);
static void wake_up_handler(void);

/******************************************************************************
 * Main Application
 ******************************************************************************/
int main(void) {
    BoardInitMcu();
    BoardInitPeriph();
    
    if (LORAWAN_Init() != LORAWAN_SUCCESS) {
        BoardDeInitMcu();
        while (1); // Hang if LoRaWAN fails
    }
    
    init_sensors();     // Initialize all sensors
    MESH_Init();        // Initialize mesh
    SOLAR_Init();       // Initialize solar
    
    TimerInit(&appTimer, wake_up_handler);
    TimerSetValue(&appTimer, SLEEP_INTERVAL_MS);
    
    while (1) {
        if (!sleepMode) {
            read_sensors();         // Read air, soil, water
            process_sensor_data();  // Process data
            send_data();            // Send via LoRaWAN/mesh
            SOLAR_Update();         // Check solar status
            enter_sleep_mode();     // Enter low-power mode
        }
        
        MESH_Process();     // Handle mesh packets
        LORAWAN_Process();  // Handle LoRaWAN events
    }
}

/******************************************************************************
 * Sensor Initialization (Air, Soil, Water)
 ******************************************************************************/
static void init_sensors(void) {
    // Air Quality (BME680)
    if (BME680_Init() != BME680_OK) {
        // Handle error
    }
    
    // Soil Sensors (ADS1115)
    if (ADS1115_Init() != ADS1115_OK) {
        // Handle error
    }
    
    // Water Sensors (DS18B20 for temp)
    if (DS18B20_Init() != DS18B20_OK) {
        // Handle error
    }
}

/******************************************************************************
 * Read All Sensors (Air, Soil, Water)
 ******************************************************************************/
static void read_sensors(void) {
    // Air Quality (BME680)
    BME680_Read(&sensorData.temperature, 
                &sensorData.humidity, 
                &sensorData.pressure, 
                &sensorData.gas_resistance);
    
    // Soil Sensors (ADS1115)
    sensorData.soil_moisture = ADS1115_ReadChannel(SOIL_MOISTURE_CHANNEL);
    sensorData.soil_npk = ADS1115_ReadChannel(SOIL_NPK_CHANNEL);
    sensorData.soil_ph = ADS1115_ReadChannel(SOIL_PH_CHANNEL);
    
    // Water Quality (ADS1115 + DS18B20)
    sensorData.water_ph = ADS1115_ReadChannel(WATER_PH_CHANNEL);
    sensorData.water_do = ADS1115_ReadChannel(WATER_DO_CHANNEL);
    sensorData.water_turbidity = ADS1115_ReadChannel(WATER_TURBIDITY_CHANNEL);
    sensorData.water_temp = DS18B20_ReadTemp();
    
    // Power Status
    sensorData.battery_voltage = BoardGetBatteryLevel();
    sensorData.solar_charging = SOLAR_IsCharging();
    sensorData.solar_voltage = SOLAR_GetVoltage();
}

/******************************************************************************
 * Process Sensor Data (Calibration & Unit Conversion)
 ******************************************************************************/
static void process_sensor_data(void) {
    // Soil Moisture (%)
    sensorData.soil_moisture = (sensorData.soil_moisture - SOIL_DRY_VALUE) * 100.0 / 
                              (SOIL_WET_VALUE - SOIL_DRY_VALUE);
    sensorData.soil_moisture = (sensorData.soil_moisture < 0) ? 0 : 
                              (sensorData.soil_moisture > 100) ? 100 : sensorData.soil_moisture;
    
    // Water pH (Calibration)
    sensorData.water_ph = (sensorData.water_ph * 14.0 / 4095.0);  // 12-bit ADC to 0-14 pH
    
    // Dissolved Oxygen (% Saturation)
    sensorData.water_do = (sensorData.water_do / 4095.0) * WATER_DO_SATURATION;
    
    // Turbidity (NTU)
    sensorData.water_turbidity = (sensorData.water_turbidity / 4095.0) * 100.0;  // 0-100 NTU
}

/******************************************************************************
 * Send Data via LoRaWAN & Mesh (Supports AQ + AG)
 ******************************************************************************/
static void send_data(void) {
    uint8_t payload[PAYLOAD_SIZE];
    int payload_len = 0;
    
    // Air Quality (4 bytes)
    payload[payload_len++] = (uint8_t)(sensorData.temperature >> 8);
    payload[payload_len++] = (uint8_t)sensorData.temperature;
    payload[payload_len++] = (uint8_t)sensorData.humidity;
    payload[payload_len++] = (uint8_t)sensorData.pressure;
    
    // Soil Data (3 bytes)
    payload[payload_len++] = (uint8_t)sensorData.soil_moisture;
    payload[payload_len++] = (uint8_t)sensorData.soil_npk;
    payload[payload_len++] = (uint8_t)(sensorData.soil_ph * 10);  // pH * 10 for precision
    
    // Water Quality (5 bytes)
    payload[payload_len++] = (uint8_t)(sensorData.water_ph * 10);  // pH * 10
    payload[payload_len++] = (uint8_t)sensorData.water_do;
    payload[payload_len++] = (uint8_t)sensorData.water_turbidity;
    payload[payload_len++] = (uint8_t)(sensorData.water_temp >> 8);
    payload[payload_len++] = (uint8_t)sensorData.water_temp;
    
    // Power Status (3 bytes)
    payload[payload_len++] = (uint8_t)(sensorData.battery_voltage * 10);  // V * 10
    payload[payload_len++] = (uint8_t)(sensorData.solar_voltage * 10);    // V * 10
    payload[payload_len++] = sensorData.solar_charging ? 0x01 : 0x00;
    
    // Send via LoRaWAN
    LORAWAN_Send(payload, payload_len, false);
    
    // Broadcast to Mesh
    MESH_Broadcast(payload, payload_len);
}

/******************************************************************************
 * Power Management
 ******************************************************************************/
static void enter_sleep_mode(void) {
    sleepMode = true;
    LOW_POWER_Prepare();
    TimerStart(&appTimer);
    LOW_POWER_Enter();
}

static void wake_up_handler(void) {
    sleepMode = false;
    TimerStart(&appTimer);
}

/******************************************************************************
 * Eco-Smart AQ/AG Mesh Node
 * Supports:
 * - Air Quality (BME680)
 * - Soil Monitoring (Moisture, NPK)
 * - Water Quality (pH, Dissolved Oxygen, Turbidity, Temperature)
 * - LoRaWAN & Mesh Networking
 ******************************************************************************/

#ifndef __CONFIG_H__
#define __CONFIG_H__

// Device Configuration
#define DEVICE_ID                 0x01        
#define DEVICE_TYPE               "AQAG-01"   
#define FIRMWARE_VERSION          "2.0.0"     

// LoRaWAN Configuration
#define LORAWAN_DEV_EUI          { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
#define LORAWAN_APP_EUI          { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
#define LORAWAN_APP_KEY          { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
                                   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
#define LORAWAN_REGION           REGION_EU868  
#define LORAWAN_ADR_ENABLED      1           
#define LORAWAN_CONFIRMED_MSG    0           

// Air Quality Sensor (BME680)
#define BME680_I2C_ADDR          0x76        

// Soil Sensors (ADS1115 for Analog Sensors)
#define ADS1115_I2C_ADDR         0x48        
#define SOIL_MOISTURE_CHANNEL    0           
#define SOIL_NPK_CHANNEL         1           // NPK Sensor (Analog)
#define SOIL_PH_CHANNEL          2           // Soil pH (Analog)

// Water Quality Sensors (Aquaculture)
#define WATER_PH_CHANNEL         3           // Water pH (Analog)
#define WATER_DO_CHANNEL         4           // Dissolved Oxygen (Analog)
#define WATER_TURBIDITY_CHANNEL  5           // Turbidity (Analog)
#define WATER_TEMP_CHANNEL       6           // Water Temperature (DS18B20)

// Calibration Values
#define SOIL_DRY_VALUE           15000       // ADC value for dry soil
#define SOIL_WET_VALUE           8000        // ADC value for wet soil
#define WATER_PH_NEUTRAL         7.0         // Neutral pH calibration
#define WATER_DO_SATURATION      100.0       // 100% DO calibration

// Power Management
#define SLEEP_INTERVAL_MS        300000      // 5 minutes sleep
#define LOW_BATTERY_THRESHOLD    3.3         // Low battery (V)
#define CRITICAL_BATTERY_THRESHOLD 3.0       // Critical battery (V)

// Solar Charging
#define SOLAR_CHARGE_THRESHOLD   4.0         // Min solar voltage (V)
#define SOLAR_MAX_VOLTAGE        5.5         // Max solar voltage (V)

// Mesh Network
#define MESH_CHANNEL             6           
#define MESH_PAN_ID              0x1234      
#define MESH_SHORT_ADDR          0x0001      
#define MESH_TX_POWER            20          // dBm
#define MESH_BROADCAST_INTERVAL  60000       // 60 sec

// Payload Configuration (Supports AQ + AG)
#define PAYLOAD_SIZE             64          // Larger payload for all sensors

// Debug Mode
#define DEBUG_ENABLED            1           
#define SERIAL_BAUDRATE          115200      

#endif // __CONFIG_H__