Turnout Card Assembly Guide

Table of contents

Introduction
System Overview:
Terminology
Assembly and Component Placement
Tools Required
Safety Precautions
Testing and Verification
Troubleshooting
Firmware Implementation Notes
Appendences

Introduction

Turnout Card

The Turnout Card is designed to work in conjunction with the LCC Fusion Node Card and Node Bus Hub to provide reliable control of up to 8 turnout motors and point sets. In typical LCC Node setups, the Turnout Card responds to LCC Events generated by input devices such as buttons, sensors, or LCC-based logic and conditional statements. This allows for precise control over track switches, enabling automated routing of trains and dynamic layout behavior.

Through the use of specialized LCC Fusion Breakout Boards, the Turnout Card supports a wide variety of switch machines, offering flexibility for different turnout control systems. The card can also be configured for 9 V or 12 V output, depending on the power requirements of your switch machines.

Key Features:

Controls up to 8 Turnout Motors: The Turnout Card manages up to 8 individual turnout motors or point sets, enabling automation of track switching and routing.
Supports Configuring up to 16 Turnout Cards per LCC Node: Each LCC Node can support up to 16 Turnout Cards, allowing for control of up to 128 individual turnout motors. This level of scalability is ideal for large, complex layouts requiring significant turnout management.
LCC Event-Driven Control: The Turnout Card responds to LCC Events generated by input buttons, sensors, or LCC Logic and Conditional statements. This allows for hands-off, automated control of turnouts based on layout activity or user-defined conditions.
Support for Various Switch Machines: Through specialized LCC Fusion Breakout Boards, the Turnout Card supports a wide range of switch machines, including:
- Servo-Based Switch Machines: For precise, programmable control of turnouts.
- Stall Motors and Slow-Motion Switch Machines: Ideal for prototypical slow-motion turnout operation.
- Single Coil and Twin-Coil Switch Machines: For quick and reliable turnout switching.
Selectable 9V and 12 V Output: The Turnout Card can be configured to provide either 9 V or 12 V output, ensuring compatibility with a variety of switch machines and turnout motors that require different power levels.
Network Cable Connectivity: The Turnout Card uses a standard network cable to connect to compatible breakout boards, simplifying installation and enabling easy expansion for multiple turnouts across your layout.

System Overview:

The Turnout Card is an integral part of the LCC Fusion system, providing seamless control over track turnouts. When triggered by an LCC Event (such as a button press or sensor activation), the Node Card processes the event and signals the Turnout Card to change the position of the associated turnout motors.

For example:

A button press or sensor triggers an LCC Event.
The Node Card interprets the event and sends a command to the Turnout Card.
The Turnout Card then adjusts the turnout motor to the required position, switching the track as needed.

flowchart LR; 
n[Node Card] <--> |"GPIO Signal (high/low)"| c["Turnout Card"];
c <--> |"Motor Control <br/> Points Status"| servo[Turnout Servo <br/>Switch Machine <br/>Breakout Board]; 
servo --> servomotor((Servo));
servo --> f1((Frog));

c <--> |"Motor Control <br/> Points Status"| slow[Turnout Slow Motion <br/>Switch Machine <br/>Breakout Board]; 
slow --> slowmotion((Motor));
slow --> f2((Frog));

c <--> |"Motor Control <br/> Points Status"| stall[Turnout Stall Motor <br/>Switch Machine <br/>Breakout Board];
stall --> stallmotor((Stall <br/> Motor));
stall --> f3((Frog));

c <--> |"Motor Control <br/> Points Status"| twincoils[Turnout Twin-coils <br/>Switch Machine <br/>Breakout Board]; 
twincoils --> 2coils((Twin <br/> Coils));
twincoils --> f4((Frog));

c <--> |"Motor Control <br/> Points Status"| coil[Turnout Single-Coil <br/>Switch Machine Breakout Board];
coil --> 1coil((Coil));
coil --> f5((Frog));

classDef lSalmonStyle fill:#FFA07A,stroke:#333,stroke-width:2px,font-size:24px;
class c lSalmonStyle;

Connectivity with Breakout Boards:

The Turnout Card connects to specialized LCC Fusion Breakout Boards via a network cable. These breakout boards are designed to support various types of switch machines, enabling the Turnout Card to handle a wide range of turnout control systems. Whether using servo-based motors, stall motors, or traditional coil-based systems, the breakout boards provide the necessary connections for precise control. Additionally, the breakout boards allow for selection between 9 V and 12 V outputs, ensuring compatibility with different types of turnout mechanisms.

Use Cases:

Track Switching: Automate the routing of trains between different tracks, allowing for hands-free operation of your layout.
Route Selection: Use sensors or buttons to trigger route changes in real-time based on train positions or user commands.
Conditional Logic Control: Combine with LCC Logic and Conditionals to automate turnout control based on the state of the layout (e.g., only switch tracks if a train is approaching).

Suggestions:

Support for Various Switch Machines: I added a section detailing how the Turnout Card, in conjunction with specialized LCC Fusion Breakout Boards, supports different types of switch machines, including servo, stall motor, single-coil, and twin-coil systems.
Selectable Output Voltage: I emphasized the ability to select between 9 V and 12 V output, ensuring compatibility with a variety of turnout control systems.
Expanded Use Cases: Examples of practical use cases were expanded, focusing on track switching, route selection, and automated control.

Let me know if this version works for you or if you’d like further adjustments!

Terminology

I²C - not defined
I²C_bus - not defined
Accessory Bus
Bus
Cleaning PCB
Component
Current Limiting Resistor
Decoupling Capacitor
Edge Card Connector
ESD Protection Diode
Ferrite Bead
GPIO Expander
HW Communications Address
HW Communications Bus
jumper_caps - not defined
LCC Configuration Tool
lcc_event_id - not defined
LCC Event Monitoring Tool
LCC Fusion Breakout Boards
LCC Fusion Cards
lcc_fusion_io_cards - not defined
lcc_fusion_node_bus - not defined
lcc_fusion_node_card - not defined
LCC Fusion Project
MCP23017
Network Cable
output_cards - not defined
Stencil
TVS Diode

For other terms, please refer to the full Terminology Guide.

Assembly and Component Placement

This section combines both the component specifications and the assembly instructions to ensure a smooth assembly process. Below is a comprehensive list of components, their placement on the PCB, and orientation details to assist you during assembly.

High-Level Steps for Assembly:

PCB for the card can be ordered from any PCB fabricator using these Gerber Files.
Clean PCB with alcohol to remove residue. See Cleaning_PCB for details.
See also: Soldering Tips
PCB Components - listing of components used for PCB assembly
PCB Parts - listing of parts used for PCB assembly

Below is a list of the PCB components used for this card (see diagram before reference):

Component Identifier	Count	Type	Value/Description	Package	Purpose	Orientation
C1 - C4	4	Capacitor-Ceramic	0.1uF, 50 V	1206, X7R	Decoupling Capacitor for IC Protection	None
C5	1	Capacitor-Polymer	100uF, 35 V	6.3x7.7, SMD	Smooths rectified DC voltage	Anode positioned toward PCB top edge
C6	1	Capacitor-Ceramic	0.33uF, 50 V	1206, X7R	Filter Capacitor for L7809 regulator input	None
C7	1	Capacitor-Ceramic	0.1uF, 50 V	1206, X7R	Decoupling Capacitor for Regulator	None
C8	1	Capacitor-Ceramic	22uF, 50 v	1206, X7R	Smoothing Capacitor for output from L7809 regulator	None
D1	1	ESD Diode	PESD1CAN	SOT-23 SMD	I²C data bus electrostatic discharge (ESD) protection	Cathode end has a brown line and positioned towards PCB left edge
FB1, FB2	2	Ferrite Bead	BLM31PG121SN1L	1206 SMD	I²C Network Bus Data Line Noise Suppression Ferrite Bead	None
J1 - J4	4	RJ45 Socket	8P8C	PTH	Network cable (CAT5/6) connection to a turnout breakout board	Fits only one way
JP1, JP2	2	Male Header	3-Pin (0.1” spacing)	PTH	Used for COMM BUS selection (I²C hardware bus) for either BUS A or BUS B.	None
JP3	1	Male Header	3-Pin (0.1” spacing)	PTH	Used to select 9V or 12 V output for motors. Set to 12 V position when not using 9V	None
R1 - R16	16	Resistor	10kΩ	1206 SMD	Limits the current between this card and the breakout board to protect the IC	None
R17 - R20	4	Resistor	10kΩ	1206 SMD	Limits the current to SW1 and MCP23017 for the I²C address	None
SW1	1	DIP / Slide Switch	3-Pin (2.54mm spacing)	PTH	Used for COMM ADDR selection (I²C address offset, 0-7).	Position so switch so ON is towards PCB left edge
U1 - U4	4	IC	74HCT00 Dual NAND Gate	SOP-20 SMD	Monitors turnout breakout board’s point position lines. Sets MCP23017 GPIO pins HIGH or LOW based on state.	IC indent (pin 1) is positioned towards PCB top edge
U5 - U12	8	IC	TC4428 Bi-directional MOSFET Driver	SOP-8 SMD	Provides 12 V to turnout breakout board, controlling motor direction based on MCP23017 GPIO pin state.	IC indent (pin 1) is positioned towards PCB bottom edge
U13	1	IC	MCP23017 I/O Expander (16 GPIO pins)	SOP-14 SMD	I/O Expander using I²C serial interface to control 16 GPIO pins	IC indent (pin 1) is positioned towards PCB top edge
VR3	1	Voltage Regulator	L7809CV	TO-220	Provides 9V for stall motor switch machines to reduce speed and noise	Position heatsink towards PCB left edge

Tools Required

List of recommended tools.

Safety Precautions

See Safety Precautions.

Testing and Verification

Configure the card:

Select the I²C bus (COMM BUS) by positioning (2) Jumper Caps on either BUS A or BUS B male header pins (JP1, JP2)
Select the I²C address (COMM ADDR) switch (SW1) by slide each of the 3 switches to either the ON or OFF position. Setting a switch to ON increments the address by 1, 2, or 4 for an address range of 0 to 7. Up to 8 devices can then be configured for BUS A and 8 for BUS B.
Select the motor output voltage (9 V or 12 V).

The following test and verifications of the card should be performed after a through inspection of the card’s soldering. Check all of the PTH component pins and SMD pads. Make sure there are no solder bridges between pins and pads.

Visual Inspection

Initial Check: Examine the board for any obvious issues like missing components, solder bridges, or components that are misaligned or not fully seated.
Solder Joint Inspection: Use a magnifying glass or a microscope to inspect solder joints. Look for cold solder joints, insufficient or excessive solder, or any shorts between pads.
Component Orientation: the IC’s are correctly oriented according to the PCB silkscreen or schematic.

Connectivity Testing

Continuity Check: Use a multimeter in continuity mode to check for shorts between power rails and ground, and to ensure there are no open circuits in critical connections.

Power-Up Tests

Assembly a tested Power Module to the LCC Fusion Node Card.
Apply Power to the Power Module and verify the following:
- Check for Hot Components: Feel for components that are overheating, which could indicate a problem like a short circuit or incorrect component.

Functional Testing

I²C Verification

Verify that the I²C connection between the LCC Fusion Node Card and the Turnout Card work. See Testing I²C Cards for details on how to test the I²C for a I²C enabled card.

Turnout Verification

After validating the LCC Fusion Node Card can connect with the Turnout Card, test each of the output lines as follows:

Connect an network cable (CAT5/6) to RJ45 connector. Use the other end of the cable with one of the turnout breakout boards, or exposed wires to connect to a turnout switch for testing.
Configure the card using an LCC CDI Configuration Tool
Test using LCC events:
1. Send the configured on/off LCC Event ID’s for each turnout motor
2. Validate that motor movements

Troubleshooting

See I²C Trouble Shooting.

Firmware Implementation Notes

The following outlines the key steps for implementing firmware to interact with the Turnout Card:

Connect I²C
- Use the I²C bus and address as configured on the card. The card’s COMM ADDR is an offset added to the I²C base address of 0x20. For example, if the COMM ADDR is set to 2 (switches set to 010), the firmware must communicate with the I²C device at address 0x22 (0x20 + 2).
Configure GPIO Ax (A0-A7) for Motor Direction Control:
- Configure A0-A7 pins on the MCP23017 as OUTPUT.
- Set the GPIO pins to HIGH or LOW to control motor direction. Depending on the configuration, a HIGH or LOW signal will move the motor in one direction or the other.
Configure GPIO B0-B7 for Point Status Reading:
- Configure B0-B7 pins on the MCP23017 as INPUT.
- Read the GPIO pin state to determine the turnout point status as either Thrown or Closed. The HIGH or LOW state of the pin will indicate the turnout’s position, but note that which state corresponds to Thrown or Closed depends on the configuration.
Note: The card’s internal IC prevents GPIO floating, so no external pull-up resistor is required.

Appendences

Specifications

Specifications for the card include:

Characteristic	Value
Power Output	9V, 12 V¹
Max Turnouts	8
Maximum Number of Cards per LCC Fusion Node Cluster	16²
LCC Fusion Node Bus Hub Connectors	1³

Output voltage to turnout motors is selectable. Suggest using 9V for stall motor switch machines (TORTOISE™ DCCconcepts) to reduce speed and noise.
The LCC Fusion Node Cluster can support up to 16 cards, distributed across two I²C hardware buses, with a maximum of 8 cards per bus.
- Note: total includes all cards using the I²C address range of 0x20 (MCP23017 IC).
GND, 5V, 12 V (optional), SLA0/SDA0, and SDA1/SCL1 (optional)

How It Works

flowchart LR;
  network["LCC Network"];
  cdi[("CDI Data")];
  fPortExpander(["GPIO Port Expander<br/>(MCP23017)"]);
  cs("Communications Bus/Address");
  
  subgraph layout ["Train Layout"];
  	direction LR;
    subgraph fIoCard ["Turnout Card (16x)"];
      direction LR;
      fPortExpander;
      driver("Motor Driver<br/>(TC4428)");
      nand("Dual NAND IC<br/>(74HTC00)");
      vs("9 V/12 V Selection") --> driver;
      cs --> fPortExpander;
      led("Status<br/>(LEDs)");
    end
    subgraph fIoBb ["Turnout<br/>Breakout Board"];
    	direction LR;
    end
    subgraph fHubBb ["Node Bus Hub<br/>Breakout Board"];
    	direction LR;
    end
    subgraph fNodeCard ["Node Card"];
      direction LR;
      cdi --> |"Config"| fNodeFw;
    end
    network --> |"LCC Events<br/>(cable/WiFi/Now)"| fNodeFw;
    fNodeFw("Firmware<br/>(ESP32)") <-->  fHubBb <--> fPortExpander;
    fPortExpander --> driver -->|"Motor Control"| fIoBb;
    fIoBb --> |"Sense Status"| nand;
    nand --> fPortExpander;
    nand --> led;
    fIoBb --> |Bidirectional Current| sm(("Switch<br/>Machines<br/>(2x)"));
    fIoBb --> |Polarity Current| frog(("Frog<br/>(2x)"));
  end

  classDef blueStyle fill:#ADD8E6,stroke:#333,stroke-width:2px,font-size:24px;
  class fNodeCard blueStyle;
  classDef cyanStyle fill:#00FFFF,stroke:#333,stroke-width:2px,font-size:24px;
  class fIoCard cyanStyle;
  classDef lSalmonStyle fill:#FFA07A,stroke:#333,stroke-width:2px,font-size:24px;
  class fHubBb,fIoBb lSalmonStyle;
  classDef lightGrayStyle fill:#d3d3d3,stroke:#333,stroke-width:2px,font-size:24px;
  class layout lightGrayStyle;

The Turnout Card is designed to interface with various turnout breakout boards, providing control over turnout motors and sensing the turnout’s position (thrown or closed). The following steps outline how the system operates:

Control of Turnout Motor Direction:
- The COMM BUS and COMM ADDR switches must be set to match the LCC CDI configuration for the Turnout Card.
- This allows the card to:
  - Receive turnout motor direction control requests from the LCC Fusion Node Card via the MCP23017 GPIO (configured using I²C commands).
  - The card utilizes a TC4428 IC to send a bidirectional current to the turnout motor through RJ45 pins 1/2 (motor 1) and pins 5/6 (motor 2). The current direction controls the movement of the turnout.
  - The current remains continuous until a request is received to change the direction.
  - The OUTPUT selection provides options for either 9 V or 12 V to the breakout boards. Using 9 V may result in quieter and slower operation for stall motor switch machines.

Turnout Point Status Reporting:

The turnout card uses sense lines connected via the RJ45 pins 3/4 and 7/8 as inputs to the 74HCT00 IC (Dual NAND).
The 74HCT00 processes the sense lines and sets a corresponding MCP23017 GPIO to either HIGH or LOW, indicating the turnout’s point status (closed or thrown).

Logic Table for Sense Lines:

Sense Line 1	Sense Line 2	Output (GPIO)	Description
Low (GND)	High (3.3 V)	High	Turnout points are closed
High (3.3 V)	Low (GND)	Low	Turnout points are thrown
High (3.3 V)	High (3.3 V)	No change	Points moving (holds last state)

Connections

Components Designator Connector Label Connector Type Connection Number Function Description

Component Designator	Connector Label	Connector Type	Connection Number	Function	Description
	NODE BUS	Card Edge	1-12	Power, Communications	Connection to Node Bus Hub
JP1, JP2	COMM BUS	3-Pin Male Header	1 - 3	Communication Bus Selection	Use 2 Jumper Caps to select the communications bus to use, `A` or `B`. Must use the selection for both JP1 and JP2 NOTE: Must match card’s CDI configuration settings.
JP3	OUTPUT	3-Pin Male Header	1 - 3	Power selection	Use Jumper Cap to select the card’s output power to either `9 V` or `12 V`
SW1	COMM ADDR	Slide Switch, 3 Position	1 - 3	Communications Address selection	Slide switches to `ON` to set communications address. Examples: all `OFF` for 0, all `ON` for 7. NOTE: Must match card’s CDI configuration settings.
J1, J2, J3, J4	TURNOUTS	RJ45 Socket	Pin 1	Motor 1: Thrown Control	Sends a pulse to throw the turnout (move to Thrown). The frog is connected to Rail A when this pin is activated.
J1, J2, J3, J4	TURNOUTS	RJ45 Socket	Pin 2	Motor 1: Closed Control	Sends a pulse to close the turnout (move to Closed). The frog is connected to Rail B when this pin is activated.
J1, J2, J3, J4	TURNOUTS	RJ45 Socket	Pin 3¹	Motor 1: Sense Pin (Turnout Status)	Returns the turnout point status for Twin-Coil Machine 1 (LOW for Thrown)
J1, J2, J3, J4	TURNOUTS	RJ45 Socket	Pin 4¹	Motor 1: Sense Pin (Turnout Status)	Returns the turnout point status for Twin-Coil Machine 1 (LOW for Closed)
J1, J2, J3, J4	TURNOUTS	RJ45 Socket	Pin 5	Motor 2: Thrown Control	Sends a pulse to throw the turnout (move to Thrown). The frog is connected to Rail A when this pin is activated.
J1, J2, J3, J4	TURNOUTS	RJ45 Socket	Pin 6	Motor 2: Closed Control	Sends a pulse to close the turnout (move to Closed). The frog is connected to Rail B when this pin is activated.
J1, J2, J3, J4	TURNOUTS	RJ45 Socket	Pin 7¹	Motor 2: Sense Pin (Turnout Status)	Returns the turnout point status for Twin-Coil Machine 2 (LOW for Thrown)
J1, J2, J3, J4	TURNOUTS	RJ45 Socket	Pin 8¹	Motor 2: Sense Pin (Turnout Status)	Returns the turnout point status for Twin-Coil Machine 2 (LOW for Closed)

RJ45 Pins 3 and 4 default to HIGH via pullup resistors on the Turnout Card. Relays set sense pins to GND when motor controls trigger switch machine to move the turnout points.

Protection

The Turnout Card is equipped with several protective components to ensure reliable operation and safeguard the board and connected devices from potential electrical issues. Below is an overview of the protection mechanisms implemented:

Protected Component	Protection Component	Function	Specifications	Location
I²C Communication Lines	PESD1CAN Diode	Protects the I²C lines from ESD (Electrostatic Discharge) and other electrical surges.	Clamping voltage: 24 V max	Located on I²C data (SDA, SCL) lines.
I²C Communication Lines	BLM31 Diodes	Provides additional protection to the I²C lines by filtering out high-frequency noise and protecting against voltage spikes.	Bidirectional TVS diode	Positioned along I²C communication lines.
I/O Control Lines	10kΩ Current Limiting Resistors	Limits the current on the motor control and point sensing lines, protecting the MCP23017 and associated circuitry.	10kΩ resistors to limit current	On the motor control and point sensing lines.
I²C Address Selector	10kΩ Current Limiting Resistors	Limits the current on the I²C address configuration pins, preventing excessive current from damaging the MCP23017.	10kΩ resistors	On the I²C address offset selector switches.
MCP23017 Port Expander	0.1µF Decoupling Capacitor	Reduces noise and stabilizes the power supply to the MCP23017, ensuring smooth operation.	Capacitance: 0.1µF	Positioned near the MCP23017 power supply pins.
L7809 Regulator	Output Capacitor	Filters out high-frequency noise and transient voltage spikes from the output, ensuring stable 12 V regulation.	Value: 10 µF ceramic	Across the output (12 V) and GND

References

Turnout Motor list: https://dccwiki.com/Turnout_Motors
I²C GPIO Mapping (Turnout Card)

The Turnout Card drives two stall motors (M1, M2) via 9V/12V outputs and receives confirmation of point movement completion from optocoupler-based sense lines (S1, S2). The sense lines are active LOW when the points are fully thrown or closed.

RJ45 Lines	Function	MCP23017 Pin	GPIO Line	Direction	Pull-up	Logic Levels	Purpose	Notes
L1/L2	Motor 1 (M1)	—	—	Output	—	—	Drives Motor 1	9V/12V output, not monitored via I²C
L3	Sense 1 A	GPA0	GP0	Input	Enabled	LOW = Active	Point reached position A	From optocoupler
L4	Sense 1 B	GPA1	GP1	Input	Enabled	LOW = Active	Point reached position B	From optocoupler
L5/L6	Motor 2 (M2)	—	—	Output	—	—	Drives Motor 2	9V/12V output, not monitored via I²C
L7	Sense 2 A	GPA3	GP3	Input	Enabled	LOW = Active	Point reached position A	From optocoupler
L8	Sense 2 B	GPA4	GP4	Input	Enabled	LOW = Active	Point reached position B	From optocoupler