Sensor Planning Guide

Table of contents

Introduction
Sensor Connection Options: Overview
1. Why Two Paths?
2. Configuration Summary: Pros & Cons
Supported Cards & Breakout Boards
Power & Voltage Planning
1. 🔌 Breakout Board Power Design
2. 🧠 Sensor Selection Tips
Firmware Configuration Basics
Examples
Advanced Sensors
Troubleshooting Tips

Introduction

The Sensor Planning Guide helps layout builders understand which types of sensors are supported by the LCC Fusion Project, how they are typically used, and which hardware components (cards and breakout boards) are required to connect them to the layout. This guide focuses on environmental, proximity, detection, and passive sensors—all of which trigger automation without direct user interaction.

If you’re looking for information on buttons, toggles, and manual control panels, please refer to the Button Card Planning Guide.Sensor Types Overview

The LCC Fusion system supports a variety of sensors for layout automation, most of which connect using a 3-pin V/G/S (Voltage, Ground, Signal) interface. These sensors typically output a digital HIGH or LOW signal and are monitored using the Sensor Card, Resistive Sensor Card, or one of several dedicated sensor cards. This section provides an overview of supported sensor types, example modules, typical use cases, and the appropriate hardware from the LCC Fusion ecosystem.

The table below summarizes the supported categories:

Sensor Connection Options: Overview

The LCC Fusion Node Card offers two primary ways to connect sensors and digital I/O devices:

Direct breakout board connection via the built-in RJ45 I/O port, and
I²C expansion card connection via the Node Bus Hub.

This flexibility was added to support both simple, low-cost setups and larger, scalable installations. As a result, you may find multiple configuration options for certain sensor types in this documentation. Choosing the best option depends on your layout size, budget, and technical requirements.

Why Two Paths?

The inclusion of an RJ45 I/O port on the Node Card was specifically intended to offer a low-effort connection method for common sensor types. This led to the development of:

The Digital Sensor Breakout Board (for up to 6 digital 3-wire sensors)
The Analog Sensor Breakout Board (for up to 8 resistive + 8 voltage-output analog sensors)

For larger or more complex sensor networks, we recommend using I²C-based expansion cards, which support up to 256 devices per Node. However, these require additional infrastructure:

A Node Bus Hub
One or more of the following: Sensor Card, Digital I/O Card, or Button Card

Configuration Summary: Pros & Cons

Connection Method	Pros	Cons
Direct (RJ45)	- Simple wiring - Lower cost - Minimal setup time	- Limited to 6 I/O lines per Node - No addressable expansion
Digital Sensor Breakout Board	- Quick connection for 3-wire digital sensors - Compact layout	- Limited to 6 sensors per Node - One board per Node
Analog Sensor Breakout Board	- Supports 2-wire and 3-wire analog sensors - Auto channel switching in firmware	- Only one breakout board type can be used at a time
I²C via Node Bus Hub	- Supports up to 256 I/O devices - Mix and match sensor types - Dynamic addressing	- Requires additional hardware (Hub + Cards) - Slightly higher cost and complexity

Supported Cards & Breakout Boards

LCC Fusion organizes sensor integration through a set of dedicated cards and breakout boards. Each card handles a specific type of input or use case and connects to breakout boards using standardized RJ45 cabling or pin headers. This section summarizes each card’s purpose and provides links to their individual planning or setup guides.

flowchart LR
  can["CAN Network"]
  subgraph layout ["Train Layout"]
    subgraph analogSensors ["Analog Sensors<br>"]
    	analogsensortitle["(2-Wire Resistive & <br>3-Wire)"]
      analogsensorlist(("LDR (Light Sensor),<br>FSR (Force Sensor),<br>Potentiometer,<br>Proxmity Sensor (Analog, IR)"))
    end
    subgraph digitalSensors ["Digital Sensors"]
      digitalsensortitle["(2-wire Switches &<br>3-Wire)"]
      digitalsensorlist(("Hall Sensor,<br>Touch Sensor,<br>Proximity Sensor (Digital, IR),<br>Rotary Encoder"))
      digitalsensorlist2(("Magnetic Proximity,<br>Mechanical Switch"))
      digitalcurrent(("Block Current"))
      digitallv(("Block Low Voltage"))
      digitalbrd(("Reversing Loop"))
      digitaluod((Proximity Detection))
      digitalrfid(("RFID Tag"))
    end
    subgraph bbs ["Breakout Boards"]
      iobb[["I/O<br>Breakout Board"]]
      analogbb[["Node Analog Sensor<br>Breakout Board"]]
    	digitalsensorbb[["Digital Sensor<br>Breakout Board"]]
      bodbb[["BOD<br>Breakout Board"]]
      lvbb[["BLVD<br>Breakout Board"]]
    	brdbb[["BRD<br>Breakout Board"]]
    	uodbb[["UOD<br>Breakout Board"]]
    	rfidbb[["RFID<br>Breakout Board"]]
    end
    subgraph hub ["Node Bus Hub"];
      iocard[["I/O Card"]]
      nodecard[["Node Card"]]
      sensorcard[["Sensor Card"]]
      buttoncard[["Button Card"]]
      bodcard[["BOD Card"]]
      lvcard[["BLVD Card"]]
      brdcard[["BRD Card"]]
      uodcard[["UOD Card"]]
      rfidcard[["RFID Card"]]
    end
    analogSensors -.-> analogbb
    digitalsensorlist -.-> digitalsensorbb
    digitalsensorlist2 -.-> digitalsensorbb
    digitalsensorlist2 -.-> iobb
    digitalcurrent -.-> bodbb
    digitallv -.-> lvbb
    digitalbrd -.-> brdbb
    digitaluod -.-> uodbb
    digitalrfid -.-> rfidbb
    
    iobb --> |"GPIO signal"|iocard;
    iobb --> |"GPIO signal"|buttoncard;
    bodbb --> |"GPIO signal"|bodcard
    analogbb -->|"voltage (0–3.3 V)"| nodecard
    lvbb -->|"GPIO signal"|lvcard
    brdbb -->|"GPIO signal"|brdcard
    uodbb -->|"GPIO signal"|uodcard
    rfidbb -->|"GPIO signal"|rfidcard
    
    iocard -->|"GPIO signal"| nodecard
    buttoncard -->|"GPIO signal"| nodecard
    bodcard --> |"GPIO signal"| nodecard
    digitalsensorbb -->|"GPIO signal"| nodecard
    brdcard -->|"GPIO signal"| nodecard
    uodcard -->|"GPIO signal"| nodecard
    rfidcard -->|"GPIO signal"| nodecard
    
    digitalsensorbb -->|"GPIO signal"| sensorcard
    sensorcard --> |"GPIO signal"| nodecard
    nodecard -->|"LCC Events:<br>car loaded (yes/no),<br>lighting (on/off),<br>magnet detected,<br>panel button pressed,<br>Block Occupiedk, <br>Block Low Voltage,<br>Block Reversing,<br>Person Detected,<br>RFID Tag Detected"| can
  end

  classDef analogStyle fill:#C1E1C1,stroke:#333,stroke-width:2px,font-size:20px;
  classDef digitalStyle fill:#ADD8E6,stroke:#333,stroke-width:2px,font-size:20px;
  classDef cardStyle fill:#FFA07A,stroke:#333,stroke-width:2px,font-size:20px;
  classDef hubStyle fill:lightblue,stroke:#333,stroke-width:2px,font-size:20px;
  classDef bbsStyle fill:yellow,stroke:#333,stroke-width:2px,font-size:20px;
  classDef bbStyle fill:lightgreen,stroke:#333,stroke-width:2px,font-size:20px;
  class bbs bbsStyle
  class hub hubStyle
  class analogSensors analogStyle
  class digitalSensors digitalStyle
  class rfidbb,uodbb,brdbb,lvbb,bodbb,analogbb,digitalsensorbb,iobb bbStyle
  class rfidcard,uodcard,brdcard,lvcard,bodcard,buttoncard,sensorcard,iocard,nodecard cardStyle
  class layout lightGrayStyle

Note:

2-wire switches like reed sensors can be connected to the Digital Sensor Breakout Board by wiring one lead to S and the other to GND, leaving the 3.3 V pin unconnected, and enabling a pull-up resistor in firmware.

🧩 General Purpose Sensor Cards

Card	Purpose	Breakout Board
Sensor Card, Node Card	Supports 6x digital sensors such as hall and touch (HTTM). Configurable per input with optional pull-up and debounce.	Digital I/O Breakout Board
Sensor Card, Node Card	Supports 6x analog resistive sensors such as LDRs, FSRs, and potentiometers. Uses op-amps for voltage amplification and conditioning before ADC input. Configurable per input with optional pull-up and debounce.	Node Analog Sensor Breakout Board
Button Card	Dedicated to passive button inputs such as fascia panel switches. GPIO lines monitored directly from 3.3 V logic.	I/O Breakout Board
I/O Card (Input/ Output Card)	More flexible than Button Card; supports 5 V, with optional 1k inline resistors. Suitable for basic digital sensors or buttons.	I/O Breakout Board

🔍 Specialized Detection & Proximity Cards

Card	Purpose	Breakout Board
UOD Card (Ultrasonic Occupancy Detection Card)	Monitors ultrasonic distance sensors (e.g., HC-SR04) to detect spacing, clearance, or presence.	UOD Breakout Board
NFC Tag Reader Card	Interfaces with NFC/RFID tag modules to identify rolling stock or trigger automation.	—
BOD Card / Block Occupancy Detection Card	Detects block occupancy by sensing current draw from trains.	BOD Breakout Board
BLVD Card / Block Low Voltage Detection Card	Monitors low voltage events (e.g., below 12 V) on power rails or track sections.	BLVD Breakout Board
BRD Card / Block Reversing Detection Card	Detects short circuits in reversing loops and triggers polarity reversal.	BRD Breakout Board

Each card integrates with the LCC Fusion Node Card and participates in the LCC network by generating LCC events upon sensor activity. For more details about wiring, configuration dialogs, or firmware behavior, refer to the documentation for each individual card.Planning Sensor Placement

The effectiveness of your automation depends heavily on the correct placement of sensors. This section offers guidelines for positioning different types of sensors around your layout to ensure reliable operation, easy maintenance, and clean wiring.🎯 General Placement Tips

Tip	Why It Matters
Plan ahead	Sensors should be designed into the layout — not retrofitted where they don’t fit.
Label your cables and sensors	Makes debugging and future upgrades significantly easier.
Use screw/spring terminals	Simplifies disconnection for sensor replacement or relocation.
Keep wiring short where possible	Reduces noise and voltage drop, especially for analog/resistive sensors.
Avoid exposure to interference	Keep sensors and wiring away from motors, DCC boosters, or high-current lines.

🧩 Sensor-Specific Placement Guidelines

Sensor Type	Placement Suggestions
Touch / Button Sensors	Mounted on fascia, control panels, or access doors for user interaction
Proximity / IR Sensors	Under track or at platform edges for train approach or stop detection
Hall / Reed Switches	Mounted between rails or beside track — detect magnets on passing rolling stock
Rotary Encoders / Pots	On fascia panels — user dials for control systems or manual overrides
LDRs (Light Sensors)	Mounted on fascia or layout base — facing up or toward ambient lighting source
FSRs (Force Sensors)	Placed under track roadbed, yards, or structures — detect physical load
Ultrasonic Sensors	Mounted overhead or at track ends — needs clear air path to target
RFID / NFC Readers	Between rails or beside track — tags on cars should pass within detection range

🔌 Breakout Board Considerations

Use breakout boards near sensor clusters to avoid long signal wire runs.
RJ45 extensions allow clean routing back to Sensor Cards mounted centrally (e.g., inside benchwork).
Consider mounting breakout boards on hinged panels or magnetic bases for easy access.

Power & Voltage Planning

The LCC Fusion Project simplifies power delivery by designing each breakout board to support the specific voltage requirements of the sensors it connects. There’s no need for users to calculate or supply their own regulated voltage — each breakout board is pre-configured to support either 3.3 V, 5 V, or both.

🔌 Breakout Board Power Design

Each sensor breakout board includes labeled power terminals and, where applicable, onboard voltage regulation. Here’s how the system works:

Card & Breakout Board	Supported Voltages	Voltage Handling
Sensor Card & Breakout Board	3.3 V and 5 V (on breakout board)	Provides both voltages; user chooses per sensor
BRD Breakout Board	3.3 V	Uses onboard op-amp with fixed 3.3 V and 100 kΩ R
UOD Card & Breakout Board	5 V	Passes 5 V to ultrasonic sensors
I/O Card & Breakout Board	5 V	Switch/jumper or card-based logic level configuration
BOD / BLVD / BRD Card & Breakout Boards	N/A (Track voltage sensing)	Powered from layout bus; no sensor voltage needed

⚠️ User Action Required

No voltage selection required on the card — each breakout board handles that for you
When using the Sensor Breakout Board, simply connect each sensor’s power wire to either the 3.3 V or 5 V terminal, depending on what the sensor requires.

🧠 Sensor Selection Tips

Sensor Specs to Check	Why It Matters
Operating voltage	Match with card/breakout board (3.3 V or 5 V)
Idle state behavior	Know if the sensor is active-high or active-low

Firmware Configuration Basics

Once your sensors are physically connected, the Node Card firmware handles input monitoring, threshold detection, and LCC event generation. Each input line can be individually configured for its type, behavior, and corresponding events.

All configuration is performed via the Node’s Configuration Dialog, typically accessed through an LCC tool (or directly via the LCC Fusion interface).

🔧 Sensor Card Configuration

Each sensor supports settings as follows:

Setting	Purpose
Card Bus Selection (A/B) and Address (0-7)	Choose which of 16 cards address is connected
Card Description and Reference ID	User defined description of the card
Sensor # (1-12)	Sensor to be configured
*For Each Sensor*
Description	Sensor description
Debounce Time (count)	Prevents false triggers from bouncing inputs (e.g., buttons, IR)
Logic Polarity	Choose whether the sensor is active-high or active-low
Event ON ID	LCC Event sent when the sensor becomes active
Event OFF ID	LCC Event sent when the sensor becomes inactive

🛠️ Node Card I/O Supported Line Types

Each line on the Sensor Card can be independently set to one of the following types:

Type	Description
Unused	Line is ignored
Digital Input – Pull-up (default HIGH)	Assumes input is pulled LOW by sensor when active
Digital Input – No Pull-up (floating)	Use for active-high sensors or externally driven signals
Digital Input – No Pull-up (default LOW)	Use when sensor pulls line HIGH
Touch Input	Reserved for touch input support
ADC Input	Used with analog inputs like LDR, FSR, potentiometers

🔧 Sensor Behavior Configuration

Each input line supports additional settings depending on type:

Setting	Purpose
Debounce Time (count)	Prevents false triggers from bouncing inputs (e.g., buttons, IR)
Logic Polarity	Choose whether the sensor is active-high or active-low
Event ON ID	LCC Event sent when the sensor becomes active
Event OFF ID	LCC Event sent when the sensor becomes inactive

For ADC Inputs, you can configure threshold values:

Setting	Description
ADC Lower Range	Minimum raw value (0–4095) to trigger ON event
ADC Upper Range	Maximum raw value (0–4095) to trigger ON event
Event ON / OFF IDs	Events fired when readings enter or exit defined range

🖥️ Serial Console Monitoring

To assist with calibration and troubleshooting, the Node firmware outputs current ADC values to the serial console during startup for any line configured as ADC Input. This lets users observe raw sensor readings and adjust their threshold settings accordingly.

Examples

Real-world layout automation cases (e.g., auto lights via LDR, car detection via FSR, beam-break crossing)
Include wiring + firmware config example per sensor
Screenshot snippets of configuration dialogs

Advanced Sensors

Reference to resistive, ultrasonic, NFC sensor support
Why they use separate cards
Link to dedicated planning pages if applicable

Troubleshooting Tips

No event? Check pull-up config
Unexpected triggers? Review logic polarity
Cable length or voltage drop?
Check breakout voltage setting (3.3 V vs. 5 V)