Chain Counter

Project Overview

This is an ESP32-based marine chain counter system (anchor rode meter) that tracks chain length and deployment speed in real-time. The system uses:

• Hardware: ESP32 microcontroller with magnetic pulse sensor and direction pin
• Connectivity: WiFi with captive portal setup, optional MQTT for SignalK integration
• Interface: Web-based dashboard with WebSocket real-time updates
• Storage: Non-volatile preferences for configuration persistence

Hardware Installation

The chain counter is powered from the anchor windlass remote control connections:

• 12V power supply: Main power from windlass control system
• 12V direction signal: Signal voltage when anchor is being lowered (chain out), voltage divided to appropriate ESP32 input level using resistor chain
• Magnetic sensor: Normally-open magnetic proximity sensor mounted in windlass base and magnet mounted under the rotating windlass component
• Shielded cable: Used for sensor connection to minimize interference from the windlass motor's high-current drive circuits

Architecture

Core Components

ChainCounter.ino - Main Arduino sketch containing:

• Interrupt-driven pulse counting with debouncing and filtering
• Adaptive speed calibration system that learns typical operating speeds
• Direction detection with hysteresis to prevent false toggles
• MQTT client with automatic reconnection and backoff
• WebSocket server for real-time web interface communication
• OTA (Over-The-Air) firmware updates
• Persistent configuration storage using ESP32 Preferences

Assets.h/cpp - Web assets stored in PROGMEM:

• HTML interface embedded as string literals
• CSS styling for responsive marine dashboard
• All web content is self-contained in the ESP32

data/ directory - Development versions of web files:

• index.html - Web interface (duplicated in Assets.cpp)
• style.css - Stylesheet (duplicated in Assets.cpp)

Key Features

• Self-calibrating speed filter: System learns normal operating speeds and filters out mechanical noise/bounce
• Direction hysteresis: Prevents false direction changes during chain slack
• MQTT SignalK integration: Publishes to standard marine data topics
• Persistent state: Chain length and calibration data survive power cycles
• WiFi auto-configuration: After restart, displays captive portal if WiFi is not available (unconfigured or network unavailable), otherwise connects automatically and makes web UI available at device IP
• Real-time web interface: Live updates via WebSocket with automatic reconnection
• Localization support: Multi-language web interface with browser language detection or manual selection via URL query string (?sv or ?lang=sv)

Development Workflow

Building and Uploading

• Use Arduino IDE or PlatformIO with ESP32 board package
• Upload via USB or OTA (password: "ota")
• Web interface accessible at device IP or chaincounter.local

Configuration

• Chain calibration: Links per pulse and links per meter
• MQTT settings: Host, port, and SignalK topic configuration
• All settings persist in ESP32 flash memory

Monitoring and Debugging

• Serial monitor at 115200 baud for debug output
• WebSerial console at http://chaincounter.local/webserial
• Available commands: restart, ip, uptime, mq (test MQTT)

Key Constants

• DEFAULT_LINKS_PER_PULSE = 10.0 - Chain links per encoder pulse
• DEFAULT_LINKS_PER_METER = 40.0 - Chain density
• INACTIVITY_MS = 2000 - Motion detection timeout
• SAVE_INTERVAL_MS = 30000 - Automatic data persistence delay

MQTT Topics (SignalK format)

• vessels/self/navigation/anchor/rodeLength - Chain deployed (meters)
• vessels/self/navigation/anchor/rodeVelocity - Deployment speed (m/s)

Circuit Diagram

Circuit diagram showing ESP32 connections to windlass remote control and magnetic sensor with voltage dividers and RC filters for signal conditioning

Hardware Photos

Circuit Board Assembly

Detailed view of the ESP32 C6 and power module connections

ESP32 C6 development board with power management module and shielded cable for magnet sensor

Complete chain counter unit in waterproof enclosure with cable glands

Finished Device

Completed chain counter in transparent enclosure showing internal components and Swedish status labels

Windlass sensor

Wndlass base with magnet sensor drilled in

Underside of windlass capstan with magnet drilled and glued in place

Web Interface

Mobile web interface showing 24.9m chain deployed at 0.5 m/s speed (chain going out)

Mobile web interface showing 23.9m chain deployed at 0.4 m/s speed (chain coming in)

Watch app Wilhelm SK shows chain length from Signal K

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Project specified and supervised by Johan Sölve, programmed by ChatGPT and Claude