PCB Schematics

HydroLink Plus PCB Schematics Documentation

Table of Contents

1. Introduction
2. Features of the PCB
3. Components and Specifications
4. Circuit Design Overview
5. PCB Layout and Design Files
6. Assembly and Soldering Instructions
7. Testing and Validation
8. Diagrams and Schematics
9. Conclusion

---

Introduction

The PCB design for HydroLink Plus integrates the ESP32 microcontroller, sensors, motorized valve control, and power regulation into a compact, efficient layout. It is designed to withstand outdoor environments while ensuring reliable performance.

---

Features of the PCB

1. Compact Design:

   • Size: 80mm x 50mm.
   • Optimized for fitting into a 3D-printed casing.

2. Multi-Sensor Integration:

   • Supports pH, turbidity, conductivity, and flow sensors.

3. Power Management:

   • Integrates MPPT solar charging and voltage regulation.
   • Supports both 12V Li-ion battery and 5V solar input.

4. Connectivity:

   • Wi-Fi and Bluetooth enabled via the ESP32 module.

5. Safety Features:

   • Overcurrent and reverse polarity protection.
   • ESD protection on external sensor pins.

---

Components and Specifications

Key Components

1. ESP32 Microcontroller:
   • Handles processing, communication, and sensor data collection.
2. CN3791 MPPT Solar Charger:
   • Manages solar input and battery charging.
3. Mini 360 Buck Converter:
   • Steps down voltage for the ESP32 and sensors.
4. Sensors:
   • pH, turbidity, conductivity, and flow sensors.
5. Motorized Valve Driver:
   • MOSFET-based circuit for controlling valves.

Additional Components

• Diodes: For reverse polarity protection.
• Capacitors: For voltage smoothing.
• Resistors: For current limiting and pull-up configurations.
• Connectors: Screw terminals for sensors and power.

---

Circuit Design Overview

Power Supply Circuit

• Solar Input (5V): Connected to the CN3791 MPPT module.
• Battery Output (12V): Connected to the Mini 360 Buck Converter for stepping down to 3.3V or 5V.
• Includes capacitors for voltage smoothing and diodes for polarity protection.

Microcontroller Integration

• ESP32 GPIO Pins:
  • pH Sensor: Analog input (GPIO34).
  • Turbidity Sensor: Analog input (GPIO35).
  • Flow Sensor: Digital input (GPIO18).
  • Valve Control: Digital output (GPIO32).
• UART: For debugging and firmware flashing.

Motorized Valve Control Circuit

• Utilizes a MOSFET for driving the motorized valve.
• Includes a flyback diode to protect against voltage spikes.

Sensor Connections

• Screw terminals for secure connections to external sensors.
• ESD protection diodes on all sensor inputs.

---

PCB Layout and Design Files

1. Software: Designed in KiCad/Altium Designer.
2. Layers:
   • Top Layer: Power and signal traces.
   • Bottom Layer: Ground plane for EMI shielding.
3. Download Files:
   • Schematic Diagram: Download Schematic
   • PCB Gerber Files: Download Gerbers

PCB Layout Diagram

(Include a labeled diagram of the PCB layout with clear identification of key components and connectors.)

---

Assembly and Soldering Instructions

1. Tools Required:

   • Soldering iron and solder wire.
   • Multimeter for testing connections.
   • Magnifying glass or microscope for inspecting solder joints.

2. Assembly Steps:

   • Start with small components like resistors and capacitors.
   • Solder ICs and connectors next.
   • Attach the ESP32 module and power management ICs last.
   • Verify all connections with a multimeter.

3. Tips:

   • Use flux for clean solder joints.
   • Keep sensor connector areas free from solder bridges.
   • Ensure all polarities (diodes, capacitors) are correct before powering the PCB.

---

Testing and Validation

Pre-Power Testing

1. Verify all solder joints with a continuity test.
2. Check for short circuits between power and ground.

Functional Testing

1. Connect a 5V solar panel and verify battery charging through the CN3791 module.
2. Power the ESP32 and check boot logs through UART.
3. Test sensor data acquisition by connecting dummy sensors.
4. Simulate valve control commands and measure MOSFET output.

Environmental Testing

• Temperature: Test PCB operation at -10°C to 50°C.
• Waterproofing: Ensure no corrosion or failure when housed in the sealed casing.

---

Diagrams and Schematics

Full Circuit Schematic

(Include a detailed, annotated circuit diagram showing all connections, components, and labels.)

PCB Layout

graph TD;
    A[ESP32 Module] --> B[Sensor Terminals];
    A --> C[Valve Driver Circuit];
    A --> D[Power Management Circuit];
    D --> E[Solar Input];
    D --> F[Battery Output];
    F --> G[Buck Converter];
    G --> H[ESP32 Power Input];

Loading