Hello, my name is Nikola Pantelin, electrical and computer engineer from Serbia.

Custom Capacitive Soil Moisture Sensor – A Smart Irrigation Solution

This custom-built capacitive soil moisture sensor combines advanced electronics, low-power design, and user-friendly functionality to revolutionize automated irrigation systems. It’s designed for developers, gardeners, and smart-home enthusiasts looking for an efficient, reliable, and easy-to-integrate solution for soil and plant monitoring.

Features in Detail

1. Soil Moisture Sensing

• Capacitive Moisture Sensor: Built with the LMV358IDR operational amplifier for accurate and stable moisture level detection.
• Reliability: Capacitive sensors are resistant to corrosion, ensuring long-term durability and precision in varying soil conditions.

2. Water Level Detection

• Powered by the TP5552-VR, the system can monitor water reservoir levels to prevent dry runs and optimize irrigation schedules.

3. Dual Temperature Monitoring

• DS18B20: Offers precise digital temperature measurements, ideal for applications requiring high accuracy.
• DHT11: Adds humidity detection, making the device suitable for climate monitoring in greenhouses or outdoors.

4. Smart Water Pump Control

• Low-Power 5V USB Type-A Water Pump:
  • Adjustable flow regulation using PWM control for optimized water usage.
  • Ideal for micro-irrigation and precision watering tasks.
• Manual Watering Switch: Enables instant manual control, providing flexibility when automation is not needed.

5. Multiple Power Options

• USB-C Port: Powers the system directly or charges the onboard CR2032 coin-cell battery.
• Battery Management System (BMS):
  • Includes the MAX17048 for advanced battery monitoring and efficient charging.
  • Ensures extended operation during power outages.

6. Voltage Regulation

• Buck Converter: Efficiently steps down voltage to 5V and 3.3V, ensuring stable operation of all components while maintaining low power consumption.

7. User-Friendly Design

• LED Indicators: Two LEDs provide real-time feedback for system status, battery health, and irrigation activity.
• Compact Form Factor: Lightweight and easy to integrate into DIY projects or existing smart irrigation setups.

Applications

• Smart irrigation for home gardens, greenhouses, and agricultural setups.
• Soil and climate monitoring in research or educational projects.
• DIY IoT projects for automated watering systems.

Why Choose This Solution?

• Customizable: Tailored for integration with IoT platforms like Arduino, ESP32, and Raspberry Pi.
• Low Maintenance: Durable components reduce the need for frequent replacement or recalibration.
• Energy-Efficient: Designed for extended operation with minimal power consumption.

M.2 Key-Based Development Board Programmer

This project focuses on creating a custom M.2 key-based programming system designed for seamless programming and debugging of custom ESP32-S3 development boards. The unique system integrates a male M.2 connector on the development board and a corresponding custom M.2 key programmer, providing a compact and reliable connection interface.

Key Features and Components

1. M.2 Keyed Connector Interface:
   • The development board features the male part of an M.2 key connector.
   • The programmer includes the female M.2 key interface, ensuring a snug, robust physical connection.
   • This configuration minimizes the wear and tear associated with traditional pin headers or cables.
2. ESP32-S3 Core:
   • The board is powered by the ESP32-S3 module, which supports Wi-Fi and Bluetooth for IoT applications.
   • It includes GPIOs that are routed through the M.2 connector for debugging and peripheral interfacing.
3. USB-C Interface:
   • A USB-C port is used for power delivery and direct communication with the programmer.
   • Integrated circuitry ensures stable voltage regulation with components like the AMS1117-3.3 voltage regulator.
4. Power Management:
   • The system operates on a 3.3V logic level provided by the voltage regulator.
   • Capacitors (10 µF and 100 nF) smooth power delivery for stable operation.
5. Programming Support:
   • The programmer handles USB-to-serial communication for firmware flashing.
   • A RESET and BOOT button circuit simplifies the process of entering programming mode.
6. Status LEDs:
   • Integrated LEDs for power and programming status provide real-time feedback.
   • GPIO-connected LEDs indicate the activity during operation.

Functional Workflow

1. Hardware Connection:
   • Plug the development board’s M.2 male connector into the programmer’s M.2 female interface.
   • The keyed connector ensures alignment and proper pin mapping.
2. Programming Mode:
   • Use the buttons on the programmer to enter the ESP32-S3’s bootloader mode.
   • The USB-C port on the programmer connects to a host PC, enabling firmware uploads via tools like ESP-IDF or Arduino IDE.
3. Power and Status Feedback:
   • The power LED confirms the device is powered.
   • Activity LEDs indicate ongoing data transmission or programming.
4. Detachable Design:
   • Once programming is complete, the development board can be detached and deployed in its intended environment, maintaining a compact profile.

Applications

This programming system is ideal for:

• Prototyping and testing IoT devices.
• Compact embedded system designs where traditional headers are impractical.
• Environments requiring durable, high-frequency programming interfaces.

The innovative use of an M.2 connector ensures a reliable and compact programming solution that caters to the evolving demands of IoT and embedded development. This approach not only enhances usability but also improves the durability of the connections, making it a valuable addition to any developer’s toolkit.

Custom IoT Development Board with M.2 Interface

Project Overview:
This custom development board is designed to streamline prototyping and testing for IoT applications, leveraging the ESP32-S3 microcontroller’s robust connectivity and low power capabilities. The standout feature of this board is its M.2 (M-key) interface, which simplifies maintenance and module replacement, making it ideal for iterative development and production environments.

System Components:

1. Core Microcontroller:
   • ESP32-S3-WROOM-1 or ESP32-S3R16 for dual-core processing, Wi-Fi 6, and Bluetooth 5.0 LE connectivity.
   • Multiple GPIOs, including specialized pins for SPI, I2C, and PWM, to interface with a variety of peripherals.
2. Power Management:
   • Integrated 3.3V regulator with capacitors for stable power output.
   • Compatibility with external power supplies or batteries, making it flexible for different use cases.
3. Connectivity and Debugging:
   • USB D+ and D- lines for easy programming and debugging.
   • UART (TX/RX) pins available for serial communication.
4. Interface Highlights:
   • M.2 Key (M):
     • High-density connector for plug-and-play module replacement.
     • Supports fast and secure mounting and unmounting, making it ideal for modular IoT setups.
   • Accessible pins via the M.2 interface for peripherals like I2C, SPI, UART, and PWM.
5. Compact Design:
   • Small form factor thanks to the M.2 standard, making it suitable for tight spaces.
   • Designed for easy integration into prototype boards or enclosures.
6. Peripheral Support:
   • Includes pins for advanced sensors and actuators (e.g., SPI flash memory, I2C peripherals).
   • Allows PWM control for motors, LEDs, and other dynamic components.
7. Reset and Strapping:
   • Onboard strapping pins and reset buttons ensure developers can easily configure boot modes and debug the microcontroller.

Key Benefits:

1. Ease of Maintenance:
   • M.2 module design simplifies hardware replacements and upgrades without soldering or reassembly.
2. Rapid Prototyping:
   • Developers can quickly swap out ESP32 modules for troubleshooting or upgrading to different ESP32-S3 versions.
3. Scalability:
   • The modular approach supports scaling up from prototyping to production without reengineering the PCB layout.
4. Flexibility:
   • Compatible with a wide array of sensors, actuators, and external components, allowing for diverse IoT applications.
5. Durability and Longevity:
   • The M.2 interface provides secure connections and minimizes wear and tear during frequent testing cycles.

Applications:

• IoT Prototyping: Ideal for developers needing a modular and easily replaceable design.
• Smart Devices: Suited for creating smart appliances, environmental monitors, or industrial IoT devices.
• Educational Use: Simplifies hardware learning with its plug-and-play architecture.

This development board bridges the gap between convenience and functionality, empowering developers to innovate quickly while maintaining high reliability. It represents a significant step forward in modular IoT design, fostering creativity and efficiency in the development process.

IoT Solar-Powered Irrigation System

Project Overview:
The Solar-Powered Irrigation System is an innovative IoT solution designed to automate plant watering in outdoor environments. This system is powered entirely by solar energy, ensuring sustainability and minimal operational costs. The core of the project is an ESP32-S3 microcontroller, chosen for its low power consumption and advanced connectivity features. The system utilizes a high-efficiency buck converter to regulate power, ensuring consistent operation even under varying solar conditions. A 5V water pump is controlled via a USB Type-A interface, with PWM control to adjust the water flow based on plant needs.

System Components:

1. Power Management:
   • Solar panel to harvest renewable energy.
   • Integrated battery and charging circuit (TP4056 module) to store energy.
   • High-efficiency buck converter (TPS63020) to provide stable 5V and 3.3V outputs for system components.
2. Microcontroller:
   • ESP32-S3 as the central controller, providing Wi-Fi/Bluetooth connectivity for remote monitoring and control.
3. Water Pump Control:
   • 5V water pump powered through a USB Type-A port.
   • PWM (Pulse Width Modulation) for precise water flow control to avoid overwatering or under-watering.
4. Sensors:
   • AM2301 temperature and humidity sensor to monitor environmental conditions.
   • Optional soil moisture sensor integration for targeted irrigation.
5. User Interface and Debugging:
   • LED indicators for power and charging status.
   • Buttons for manual pump control and system reset.
6. Additional Features:
   • MAX17048 battery fuel gauge for monitoring battery levels.
   • Ultrasonic sensor (HC-SR04) for water level or distance measurement in reservoirs.

Key Benefits:

1. Energy Efficiency:
   • Solar-powered operation reduces dependency on external power sources.
   • High-efficiency buck converter minimizes energy losses.
2. Resource Conservation:
   • Optimized water usage with PWM-controlled pump and environmental sensors.
   • Remote monitoring allows precise scheduling and adjustments.
3. Scalability:
   • Modular design allows integration with other IoT devices.
   • Expandable to larger irrigation systems.
4. Cost-Effective:
   • Reduces labor and water costs through automation.
   • Sustainable solar energy eliminates electricity expenses.
5. Environmentally Friendly:
   • Renewable energy-based operation minimizes carbon footprint.
   • Promotes efficient water usage in agriculture and gardening.

This system is ideal for smart gardening, urban farming, and agricultural applications where efficient water management is critical. With its advanced features and eco-friendly design, it provides a modern solution to traditional irrigation challenges.

LED Brightness Regulator, High Voltage Relay, Temperature and Humidity

Introduction:
The project aimed to design a professional-grade printed circuit board (PCB) capable of efficiently controlling LED brightness, managing a 230V relay, and monitoring temperature and humidity.

Leveraging the ESP32-S3 chip, renowned for its versatility and robustness, the design process followed rigorous engineering standards to ensure safety, reliability, and optimal performance.

Power Management:
Safety was prioritized in the power supply design.

A meticulous approach was taken to step down the 230V AC mains power to a stable 12V DC with the help of the HLK-20M12, providing a safe and efficient voltage level for LED illumination.

Subsequently, a sophisticated buck converter was integrated to further regulate the power, generating 5V for sensor operation and 3.3V for the ESP32 microcontroller and associated buttons.

Control Interface:
The local user interface was carefully crafted to provide seamless control and operation.

Various buttons, including the SMD boot button for ESP32 download mode initiation, a reset button for system reset functionality, and a dedicated button for local activation of the 230V relay, were strategically placed for accessibility and ease of use.

Additionally, a high-quality potentiometer was incorporated to enable precise control over LED brightness, enhancing user experience and functionality.

Sensor Integration:
Central to the design was the incorporation of temperature and humidity sensors, pivotal for comprehensive environmental monitoring.

Carefully chosen for their precision and dependability, these sensors deliver real-time data, crucial for maintaining ideal environmental parameters.

Moreover, these sensors are meant to seamlessly integrate with Home Assistant via MQTT.

This integration will enable dynamic control over my climate system, allowing for precise adjustments to heating, cooling, and humidity levels based on real-time environmental data.

PCB Layout and Prototyping:
The PCB layout was meticulously designed to optimize signal integrity, minimize interference, and maximize space efficiency.

Through iterative prototyping and rigorous testing, potential design flaws were identified and addressed, resulting in a refined and robust final product.

The layout adheres to industry standards, ensuring compatibility with manufacturing processes and facilitating scalability for future iterations.

Conclusion:
The completed PCB design stands as a testament to my professionalism, innovation, and meticulous attention to detail.

By seamlessly integrating LED brightness control, 230V relay management, and environmental monitoring capabilities, it offers a comprehensive solution for a wide range of applications.

As a versatile platform built on the foundation of the ESP32-S3 chip, it represents the pinnacle of engineering excellence, poised to meet the challenges of today and tomorrow with unwavering precision and reliability in the IoT industry.

Check out the schematic and PCB design on my github.