Node Card Assembly Guide

[TOC]

Table of contents
  1. Node Card Assembly Guide
    1. Introduction
    2. Assembly-Configuration Options
    3. Assembly and Component Placement
    4. Tools Required
    5. Safety Precautions
    6. Testing and Verification
      1. Card Configuration
      2. Visual Inspection
      3. Connectivity Testing
      4. Power Input/Output Tests
      5. ESP32 Communications Testing
      6. Node Card Auto Testing (Using Serial Monitor During Firmware Startup)
      7. Node Card Testing (Using Serial Monitor Testing Program)
    7. Troubleshooting
    8. Appendences
      1. Specifications
      2. How It Works
      3. CAN Network
      4. Connections
      5. Protection
      6. Flow of current
      7. References

Introduction

See the How to Use Assembly Guides for detailed instructions.

Download this guide ( PDF, EPUB )

Node Card

In conjunction with the Node Bus Hub, the LCC Fusion Node Card provides an LCC compatible Node with ON/OFF control for up to 8 separate I/O devices. Typically, in an LCC Fusion Project LCC Fusion Node Cluster arrangement, there will be a Node Bus Hub, with one LCC Fusion Node Card, an optional I/O cards.

The LCC Fusion Node Card can be implemented with a number of optional features:

  1. Power Supply options (see Power Module for more details):
    1. 12 V+ input via a network cable (CAT5/6), USB-C socket, 5557 ATX connection, or a DC-005 barrel connection.
    2. 12 V+ output via 5557 ATX connection for powering other LCC Fusion Node Cards.
    3. 5V+ output via USB-C for powering low voltage devices (e.g. RPI).
  2. CAN serial connection via a network cable (CAT5/6) or connectors (JST XH or Spring terminal).
  3. CANable adapter for Windows USB to CAN connection for JMRI integration.
  4. CDI reset button (hold for 10 seconds to reset the CDI to factory setting)
  5. Reset button to restart the Node.
  6. LCC Fusion Node Bus Hub(RJ45) network cable connection to connect with a remote LCC Fusion Project Node Bus Hub

CAN Communications

The LCC Fusion Node Card connects to a CAN Network, enabling communication of LCC Events. It features two RJ45 sockets for easy in/out connections, allowing multiple Node Cards to be daisy-chained together. To simplify the network setup, the Node Card includes an auto-termination circuit, ensuring the correct 120 Ī© termination is automatically applied to the last device in the chain, eliminating manual setup.

Below is a diagram illustrating the daisy-chaining of Node Cards via their RJ45 sockets with automatic CAN termination:

flowchart LR;
subgraph nodecard["Node Card (1)"];
direction LR;
esp32.1["ESP32"];
end;
subgraph nodecard2["Node Card (2)"];
direction LR;
autoterm2["CAN Auto-Termination (on)"]
esp32.2["ESP32"];
end;
can["CAN Network"];
can <-.-> |"Network Cable"| esp32.1;
esp32.1 <-.-> |"Network Cable"| esp32.2 <-.-> autoterm2;

classDef lSalmonStyle fill:#FFA07A,stroke:#333,stroke-width:2px,font-size:24px;
class nodecard,nodecard2 lSalmonStyle;
classDef lightGrayStyle fill:#d3d3d3,stroke:#333,stroke-width:2px,font-size:24px;
class can lightGrayStyle;

I2C Communication

The LCC Fusion Node Card supports I2C serial communication to interface with various I/O cards. Each device on the I2C bus is assigned a communication address and an address offset. The Node Card supports two I2C buses (Bus A and Bus B) with offsets ranging from 0 to 7.

Pullup resistors are used to ā€œconditionā€ the I2C lines (SDA and SCL), ensuring proper signal levels by pulling the lines to a high state when not actively driven. Conditioning of the I2C to maintain proper voltage levels is handled automatically.

Below is a diagram showing how I2C serial communication is used between the Node Card and multiple I/O cards:

flowchart LR;
subgraph nodebushub["Node Bus Hub"];
direction LR;
subgraph nodecard["Node Card"];
direction LR;
esp32["ESP32"];
end
card1["I/O Card <br/> (MCP23017 IC)"];
card2["I/O Card <br/> (PCA9685 IC)"];
card3["I/O Card <br/> (ESP32 Module)"];
display["Display Monitor"];
storage["Micro-SD Card Reader"];
conditioning["I2C Conditioning"];
end
esp32 <-.-> |"I2C Serial <br/> (BUS A; ADDR 00)"| card1;
esp32 <-.-> |"I2C Serial <br/> (BUS A; ADDR 01)"| card2;
esp32 <-.-> |"I2C Serial <br/> (BUS B; ADDR 07)"| card3;
esp32 <-.-> |"I2C Serial <br/> (BUS A; ADDR xx)" | display;
esp32 <-.-> |"SPI" | storage;
card1 <--> device1["devices (16x)"];
card2 <--> device2["devices (16x)"];
card3 <--> device3["devices"];
classDef lSalmonStyle fill:#FFA07A,stroke:#333,stroke-width:2px,font-size:24px;
class nodecard lSalmonStyle;
classDef lightGrayStyle fill:#d3d3d3,stroke:#333,stroke-width:2px,font-size:24px;
class can lightGrayStyle;

I/O Connections

The LCC Fusion Node Card features an RJ45 socket for connecting up to 8 I/O devices, enabling direct interaction with a variety of peripherals. Supported I/O devices include:

  • Touch pads
  • LEDs
  • Relays
  • DC motors
  • Buzzers
  • Solenoids / Electromagnets
  • Fans

Below is a diagram showing how a network cable is used to connect multiple I/O devices directly to the Node Card via its RJ45 socket:

flowchart LR; 
can1["CAN Network"];
can2["CAN Network"];
n1["Node Card <br/>(I/O Connection, RJ45)"];
n2["Node Card <br/>(I/O Connection, RJ45)"];
bb1[I/O Breakout Board];
bb2[I/O Breakout Board];

subgraph layout ["Node Card I/O Flow"];
direction LR;
idevice["Input Device (8x)"] --> |"Digital Input <br/>(high/low)"| bb1;
bb1 --> |"GPIO Input <br/> (high/low)"| n1;
idevice --> |"GPIO Input <br/> (high/low)"| n1;
n1 -.->|"LCC Event<br/>(on/off)"| can1;

can2 -.-> |"LCC Event<br/>(on/off)"|n2;
n2 --> bb2;
bb2 --> |"Digital Output<br/>(high/low)"| odevice["Output Device (8x)"];
n2 --> |"Digital Output <br/> (high/low)"| odevice;

end;
classDef lSalmonStyle fill:#FFA07A,stroke:#333,stroke-width:2px,font-size:24px;
class n1,n2 lSalmonStyle;
classDef lightGrayStyle fill:#d3d3d3,stroke:#333,stroke-width:2px,font-size:24px;
class layout lightGrayStyle;
## Terminology

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

Assembly-Configuration Options

The Node Card supports multiple assembly configurations to fit various use cases.

Print PCB With Options

The PCB diagram shown above highlights different components based on their associated configuration. Each color-coded component corresponds to a specific configuration, which is further detailed in the table below.

To use this reference effectively:

  • Match the Colors: Each assembly option in the table has a matching color in the PCB diagram. This helps identify which components are needed for a specific configuration.
  • Locate Components Quickly: The highlighted component designators (e.g., D5, J1, JP1) on the PCB indicate where each part is placed.
  • Identify Required vs. Optional Parts: The table differentiates between required components (essential for functionality) and optional components (enhancements or variations).
  • Cross-Reference for Clarity: If youā€™re unsure about a partā€™s placement, use the designator labels on the PCB along with the descriptions in the table.

This approach ensures a clear, visual guide for assembling the Node Card based on your specific needs.

Print Table
Configuration Required/Optional Description Required Components Optional Components
ESP32 & I2C Support Required Provide ESP32 DevKit-C Module Support for Node ā€¢ ESP32 DevKit-C Headers (U1)
ā€¢ I2C Noise Filtering: Ferrite Beads FB3, FB4, FB5, FB6		 I2C Bus Protection: Diode D6, D10 (for ESD protection on the I2C data bus)
ā€¢ Reboot Button (S1)
ā€¢ CDI Reset Button (S2)
CAN Termination Support Required I2C Low Voltage Dection and Correction ā€¢ Voltage Comparator (U3, ZD1, R1, R2)
ā€¢ 120$\Omega$Ā Switching Circuit R3, R4, C7, Q1, Q2)		 None
Power-Input Required Provides power input connectors with high-voltage transient protection and input filtering. ā€¢ TVS Protection: diode D1
ā€¢ Reverseā€‘polarity Protection: diode D2
ā€¢Reverse Current Protection diodes D4, D5, D8
ā€¢ Overcurrent Protection: Slowā€‘burn fuse F1
ā€¢ 3A Fuse Holder: FH1 with 3A fuse		 ā€¢ USBā€‘C Power In Socket (J1)
ā€¢ Wired Power In Connector J2
ā€¢ DCā€‘005 Power In Connector (J3)
3.3 V Output Required Supplies regulated 3.3 V to the Node Bus. ā€¢ 3.3 V Regulated Output (VR3)
ā€¢ Reverse Current Protection: Diode D7		 None
5 V Output Required Supplies regulated 5V to the Node Bus with proper filtering and protection. ā€¢ 5V Regulated Output: Buck regulator VR2 accompanied by filter capacitors C5 (100ā€ÆĀµF). C2, C6 (100ā€ÆĀµF), C4 (0.33ā€ÆĀµF), C9 (1nF),Ā C10 (0.1ā€ÆĀµF), andĀ , C11 (1ā€ÆĀµF), inductor L1, voltage divider resistors R13 (3.3K$\Omega$) and R14 (1K$\Omega$)
ā€¢ Reverse/Output Protection: Diode D8		 ā€¢ 5V USB-C Output Connector (J9)
12 V Output Required Provides regulated 12 V (or higher) for powering external devices and the LCC Fusion Node Bus Hub. ā€¢ 12 V Regulated Output: Voltage regulator VR1, capacitors C3 ( 0.1uF) and C2( 0.33uF)
ā€¢ Reverse/Output Protection: Schottky diodes D4, D5, D9
 ā€¢ 12 V Output Connectors: J4 (for 12 V @ 3A output)
CAT-Wired CAN BUS Option Optional Enables wired CAN Bus connectivity over CAT network cable, supporting data exchange with other LCC Fusion Nodes. ā€¢ Reverse Polarity Protection: Diode D10 (protects input power from CAN Bus connectors)
ā€¢ CAN Bus Noise Suppression: Ferrite beads FB1 and FB2		 ā€¢ CAN Bus Connections: RJ45 connectors J5 and/or J6
ā€¢ ESD Protection: Diode D3
Indicators and Controls Support Option Optional Setup for Power Indicators and Firmware Controls ā€¢ Power Indicators (LED2, LED3, LED4, R6, R7, R8)
ā€¢ Voltage Divider for 12 V Detection (R10, R11)		 ā€¢ Blown Fuse Indicator (LED1, R9, C8)
ā€¢ Buzzer (SG1)
ā€¢ ALERT Indicator (LED5,R12)
Battery Backup Support Option Optional Enables battery backup for increased system availability. ā€¢ Battery Connector: J12 None
Increased File Storage Option Optional Setup for connecting Micro SD-Card Reader (use is TBD) ā€¢ SPI Connector (J10) None
Display Mointor Option Optional Setup for connecting an I2C enabled display monitor ā€¢ I2C Connector (J13) None
Remote Node Bus Hub Support Option Optional Setup for connecting to a remote Node Bus Hub ā€¢ Network Cable Connection to remote Node Bus Hub (J8) None
I/O Device Support Option Optional Setup for supporting I/O Devices (e.g., LEDs, buttons) through network cable. ā€¢ I/O Device Connector (J7) None

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:

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

Print PCB Node Card PCB
Print
Component Identifier Count Type Value Package Purpose Orientation
Capacitors Ā  Ā  Ā  Ā  Ā  Ā 
C1 1 Ceramic Capacitor 22 uF, 50 V 1206 X7R Used by 12V voltage regulator for input filtering None
C2 1 Polymer Capacitor 100 ĀµF, 35 V 6.3x5.8mm , SMD Used by 12V voltage regulator for input filtering Anode positioned toward PCB top edge
C3 1 Ceramic Capacitor 0.33 uF, 50 V 1206 X7R Used by 12V voltage regulator for input filtering None
C4 1 Ceramic Capacitor 0.1 uF, 50 V 1206 X7R Used by 12V voltage regulator for output filtering None
C5 1 Ceramic Capacitor 10 uF, 50 V 1206 X7R Used by blow fuse circuit to cause slow LED fade in/out None
C6 1 Ceramic Capacitor 0.1 uF, 50 V 1206 X7R IC protectionĀ (U1) None
C7 1 Ceramic Capacitor 0.1 uF, 50 V 1206 X7R Used by 5V voltage regulator for input filtering None
C8, C13 2 Polymer Capacitor 100 ĀµF, 35 V 6.3x5.8mm , SMD Used by 5V voltage regulator for input/output filtering Anode positioned toward PCB top edge
C9 1 Ceramic Capacitor 0.1 uF, 50 V 1206 X7R Used by 3V3 voltage regulator for input filtering None
C10 1 Ceramic Capacitor 10 uF, 50 V 1206 X7R Used by 3V3 voltage regulator for input filtering None
C11 1 Capacitor-Ceramic 0.1uF, 50 V 1206 X7R Used by 3V3 voltage regulator for output filtering None
C12 1 Ceramic Capacitor 47 uF, 50 V 1206 X7R CAN termination circuit None
C14 1 Capacitor-Ceramic 1n F, 50 V 1206 X7R Shunts LM2596S-ADJ output high freq spikes None
C15 1 Polymer Capacitor 100 ĀµF, 35 V 6.3x5.8mm , SMD Used by 3V3 voltage regulator for output filtering Anode positioned toward PCB top edge
Diodes Ā  Ā  Ā  Ā  Ā  Ā 
D1 1 TVS Diode SMBJ18A SMB SMD Protects from high-voltage transients (>29 V) Cathode end has a white line and positioned towards PCB right edge
D2, D4, D5, D7, D8, D9 6 Schottky Diode SS310 SMA Reverse polarity and current protection Cathode end has a white line and positioned towards PCB bottom edge
D3, D6, D10 3 ESD Diode PESD1CAN SOT-23 SMD I2C data bus ESD protection Fits only one way
ZD1 1 Zener Diode 2.4 V BZT52 2.4 V reference voltage Cathode end has a white line and positioned towards PCB right edge
Fuses & Protection Ā  Ā  Ā  Ā  Ā  Ā 
FH1 1 Fuse Holder 1808 with 3A SMD Protects from sustained overcurrent conditions None
F1 1 PTC Polymer Fuse JK30, 1.5A, 16 V (or more) 5.1mm pitch, PTH Overcurrent protection None
Filters & Noise Suppression Ā  Ā  Ā  Ā  Ā  Ā 
FB1, FB2 2 Ferrite Bead BLM31PG121SN1L 1206 SMD CAN Network Bus Data Line Noise Suppression Ferrite Bead None
FB3, FB4 2 Ferrite Bead BLM31PG121SN1L 1206 SMD I2C Data Line Noise Suppression Ferrite Bead None
Connectors Ā  Ā  Ā  Ā  Ā  Ā 
J1 1 USB-C Socket 4-Pin SMD Power input connector to power the LCC Fusion Node Card when power is not being supplied via the CAN Network Bus network cable Fits only one way
J2 1 Connector 5557 ATX RA PTH Power input connector to power the LCC Fusion Node Card when power is not being supplied via the CAN Network Bus network cable GND pin is marked on board with square pad
J3 1 Power Jack DC-005 PTH Power input connector to power the LCC Fusion Node Card when power is not being supplied via the CAN Network Bus network cable Fits only one way
J4 1 Connector 5557 ATX RA PTH Power input connector to power the LCC Fusion Node Card when power is not being supplied via the CAN Network Bus network cable GND pin is marked on board with square pad
J5-J8 4 RJ45 Socket 8P8C PTH CAN Bus and I/O networking Fits only one way
J9 1 USB-C Socket 4-Pin SMD Power output connector for external devices Fits only one way
J10 1 Header 6-Pin Male PTH Mounting for Micro-SD Reader Module None
J11-J12 2 Female Headers 19-Pin PTH Mounting for ESP32 DevKit-C module None
J13 1 Header 4-Pin PTH Mounting for I2C display monitor as a serial monitor None
Inductors & Resistors Ā  Ā  Ā  Ā  Ā  Ā 
L1 1 Inductor 33uH 8x10mm, PTH Used for 5V voltage regulation None
R1 1 Resistor 1k Ī© 1206 SMD Current limiting for reference voltage None
R2 1 Resistor 100 Ī© 1206 SMD Low Pass Filter for low signal detection None
R3, R4 2 Resistor 60 Ī© 1206 SMD CAN termination circuit None
R5 1 Resistor 1.5k Ī© 1206 SMD Part of CDI Factory Reset circuit None
R6-R9, R12 5 Resistor 1k Ī© 1206 SMD Current limiting for power output and alerts LEDs None
R13 1 Resistor 3.3k Ī© 1206 SMD Regulator voltage divider (R2) damping lower freq. None
R14 1 Resistor 1k Ī© 1206 SMD Regulator voltage divider (R1) None
R15-R18 4 Resistor 47 Ī© 1206 SMD Edge damping of I2C data lines None
R19, R20 2 Resistor 47 Ī© 1206 SMD Edge damping of CAN bus lines None
Switches & Indicators Ā  Ā  Ā  Ā  Ā  Ā 
LED1-LED5 5 LEDs Red/Green 1206 SMD Status and alert indicators Reference back of LED, position cathode towards PCB left edge
S1, S2 2 Tact Button Switch N/A SMD Factory reset or reboot buttons Fits only one way
SG1 1 Buzzer 3V Piezo Active Buzzer, 9650-5 V, SMD Buzzer for firmware generated error/warning alerts None
ICs Ā  Ā  Ā  Ā  Ā  Ā 
U1 1 CAN Transceiver SN65HVD233DR SMD CAN Communications Package has small dimple in corner (pin 1) which is position to PCB top/rightĀ edges
U2 1 MCU (Processor) ESP32 DevKitC-V4 Module /w ESP32-WROOM-32D 4MB PTH, 38-Pin wide Main processor for Node Card Position ESP32 development boardā€™s USB connector to PCB right edge
U3 1 Voltage Comparator LM393 or LM2903N SO-8, SMD Detects low voltage in I2C lines Package has small dimple in corner (pin 1) which is position to PCB top/leftĀ edges
Voltage Regulators Ā  Ā  Ā  Ā  Ā  Ā 
VR1 1 Voltage Regulator L7812CV TO-220 PTH 12 V regulator for Node Bus Hub Heat sink towards top of board
VR2 1 Voltage Regulator LM2596S-ADJ SMD 5V regulator for ESP32 & Node Bus Hub Fits only one way
VR3 1 Voltage Regulator LM1117-3V3 IC SMD 3.3 V regulator for Node Bus Hub Fits only one way

Tools Required

List of recommended tools.

Safety Precautions

Testing and Verification

Card Configuration

  1. If the LCC Fusion Node Card is at the end of the CAN Bus Network, set the CAN TERM selection to TERMINATION (single jumper caps positioned across the top 2 pins).
  2. If the LCC Fusion Node Card is not at the end of the CAN Bus Network, set the CAN TERM selection to No-Term (2 jumper caps each positioned vertically on the left and right set of pins).

Visual Inspection

  1. Initial Check: Examine the board for any obvious issues like missing components, solder bridges, or components that are misaligned or not fully seated.

  2. 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.

  3. Component Orientation: the ICā€™s are correctly oriented according to the PCB silkscreen or schematic.

Connectivity Testing

  1. 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 Input/Output Tests

Power input and output testing ensures that voltage levels are accurate, components are properly placed, and connections remain continuous across the Node Cardā€™s power circuits. These tests verify the integrity of each power rail, helping identify any potential issues before installing sensitive components.

Perform each step below in sequence. When checking voltage (V), set a multimeter to DC voltage mode and measure across V+ and GND connections. For continuity checks (** Ī©), switch the multimeter to **resistance mode and measure both ends of the connection to confirm a low-resistance path.

NOTE: Do not install the ESP32 until all voltages are verified to avoid potential damage.

NOTE: If the expected results are not met, consider the following actions:

  1. Re-verify the orientation of components listed in Pre-Reqs.
  2. Check soldering for poor connections or solder bridges between SMD legs and PTH pins.
  3. Temporarily remove optional components, such as protection diodes, to isolate the issue.
  4. Replace the component with a known good equivalent if the issue persists.
Test Description Pre-Reqs Test Points Expected Result
Verify GND Connection None BATT GND connection and NODE BUS GND pads Ī©0
Verify Blown Fuse Indicator 1. Attach >14 V power supply with circuit protection to
PWR IN ATX 5557 connector (J1, pins 1 and 2)
2. Check for Hot Components: Feel for
overheating components		 None Red LED1 fades in/out indicating blown (or no fuse in FH1) and FUSE BYPASS is not selected
Verify No Short Circuits 1. FUSE BYPASS (JP1) set to bypass the fuse
using a Jumper Cap
2. Verify orientation of protection diodes D1 and D9		 PWR OUT (J4), across ATX 5557 V+ (pin 1) and GND (pin 2) 1. Red LED1 is not on
2. Match input voltage
Verify POWER Indicators None None POWER indicators 3V3, 5 V, 12 V (Green LEDs) are all on
Verify PWR IN Power Input Connections 1. PWR INUSB-C socket (J2) using V+ (pins 2, 3)
and GND (pins 1,4)
2. PWR IN DC-005 connector (J3) using V+/GND as labeled		 PWR OUT (J4), across ATX 5557 V+ (pin 1) and GND (pin 2)
NODE BUS pads, across 12 V and GND pads		 Match input voltage13
Verify CAN BUS Power Input Connections Attach >14 V power supply to each of the CAN BUS RJ45 sockets (J5/J6): V+ (pins 3,4) and GND (pins 7,8) NODE BUS pads, across 12 V and GND pads Match input voltage1
Verify BATT Power Input Connection Attach >14 V power supply to BATT (JST XH, Screw/Spring Terminal, J12) pins 1,2 NODE BUS pads, across 12 V and GND pads Match input voltage1
Verify 3A Fuse 1. Remove FUSE BYPASS selection
2. Install 1808 3A fuse in fuse holder (FH1) 3. Attach power supply to one of the power input connectors		 PWR OUT (J4), across ATX 5557 V+ (pin 1) and GND (pin 2) Match input voltage1
Verify NODE BUS 12 V Pad 1. Verify the orientation of the voltage regulator (VR1) NODE BUS pads, across 12 V and GND pads ~11.5 V1
Verify NODE BUS 5V Pad 1. Verify orientation of filter capacitors C5 and C6
2. Verify orientation of protection diode D10		 NODE BUS pads, across 5 V and GND pads ~5 V2
Verify 5 V OUT Connection Verify the USB-C socket alignment and soldering 5 V OUT USB-C (J9), across V+ (pins 2,3) and GND (pins 1,4) ~5 V2
Verify NODE BUS 3V3 Pad Verify orientation of diode D8 NODE BUS pads, across 3V3 and GND pads ~3.3 V3
Verify CAN BUS Termination n/a CAN BUS (J5/J6) CAN-H (pin 1) and CAN-L (pin 2) >120 Ī©4
Verify IO DEVICES Connection n/a IO DEVICES (J7) pins 1-8 and NODE BUS GND tab 0V

Footnotes:

  1. 12 V Pad Voltage Drop: The expected output voltage is slightly lower than the input voltage (~0.5 V) due to SS310 protection diodes.
  2. 5 V Pad Voltage Drop: The 5V output voltage may show a minor variance from exactly 5V due to protective diode voltage drops.
  3. 3V3 Pad Voltage Drop: The 3V3 pad voltage may show a minor variance from exactly 3.3 V due to protective diode voltage drops.
  4. open circuit (>120 Ī©): When only one CAN network device (e.g. LCC Node) is on the network, no CAN Network termination resistor is applied by the auto-termination circuitry.

ESP32 Communications Testing

This section confirms the functionality of both CAN Network and I2C Serial communication components and connections on the Node Card. Before testing, ensure the ESP32 module is installed only after verifying the 5 V power supply is present.

Use a multimeter to check for expected voltage levels during each step, following the sequence outlined below. For each test:

  • Voltage checks: Set the multimeter to DC voltage mode and measure across the designated test points.
  • Continuity checks (if applicable): Use resistance mode to confirm a low-resistance path.

Note: During testing, monitor the Red LED on the DevKit-C Module to confirm ESP32 power status.

Test Description Pre-Reqs Test Points Expected Result
Verify ESP32 Module 1. Attach power supply to one of the power inputs
2. Verify ~5 V at ESP32 module (U2) across Vin and GND pins
3. Install DevKit-C Module (U2) while verifying orientation (USB connection position towards PCB right edge. Recommend using 19-Pin female headers for easy removal of the ESP32 module.		 n/a Red LED power indicator on the DevKit-C Module is On. (If not, verify orientation and check voltage at Vin.)
Verify CAN BUS Communication Connections 1. Verify CAN transceiver (U1) orientation
2. Verify Ferrite Bead (FB3) is soldered correctly
3. Verify ESD Diodes (D6, D7) are soldered correctly		 1. CAN BUS (J5/J6) pins, CAN-H (pin 1) and GND (pin 3)
2. CAN BUS (J5/J6) pins, CAN-L (pin 2) and GND (pin 3)		 ~2.25 V - 2.5 V (both lines similar during idle state)
Verify CAN I/O Communications Connection 1. Verify Ferrite Beads (FB5, FB6) are soldered correctly
2. Verify ESD Diode (D7) is soldered correctly		 1. CAN I/O (J11) pins, CAN-H and GND
2. CAN I/O (J11) pins, CAN-L and GND		 ~2.25 V - 2.5 V (both lines similar during idle state)
Verify NODE BUS I2C Communications 1. Verify Ferrite Beads (FB3, FB4) are soldered correctly
2. Verify ESD Diode (D6) is soldered correctly		 1. NODE BUS tabs, SDA0 and GND
2. NODE BUS tabs, SCL0 and GND
3. NODE BUS tabs, SDA1 and GND
4. NODE BUS tabs, SCL1 and GND		 ~3.3 V (both lines similar during idle state)
Verify CAN BUS Termination 1. Node Card is not connected to the CAN network
2. Verify voltage comparator (U3) orientation
3. Verify Zener Diode (ZD1) orientation
4. Auto-termination components
(U3,ZD1,Q1,Q2,R3,R4,C7)
are soldered correctly		 CAN BUS (J5/J6) pins, CAN-H (pin 1) and CAN-L (pin 2) 120$\Omega$Ā (when Node Card is the only device connected)
Verify NODE REBOOT Tactile Button Press NODE REBOOT (S1) button once. When no button is installed, momentarily short pads 1 and 2 together n/a ESP32 power (RED) LED turns off and then on (indicating a reboot)

Node Card Auto Testing (Using Serial Monitor During Firmware Startup)

Test Description Pre-Reqs Expected Result
Verify Firmware Startup with Serial Monitor 1. Upload the ā€˜LCC Node Cardā€™ firmware to the ESP32.
2. Attach power supply to any power input. 3.
Insert DevKit-C Module (U2), ensuring the USB connection faces the
right edge of the PCB.
4. Attach ESP32 to computer using USB cable.
5. Open serial console, set the port (e.g., COM3) and
baud rate (115200).		 [I] LCC Node: Started message is displayed
Verify Voltage To ESP32 After completing starting of firmware with serial monitor [W] Low Voltage from power supply to ESP32 message is NOT displayed
Verify 12 V To NODE BUS HUB After voltage test completion [W] Low Voltage from power supply to 12 V message is NOT displayed
Verify NODE BUS I2C Communications (BUS A, BUS B) After voltage test completion [I] I/O Card Communications is working message is displayed
Verify NODE BUS CAN Communications After I2C communications test completion [I] Successfully connected to CAN Network message is displayed
**Verify I/O DEVICES Connectivity To Devices ** After CAN communications test completion [I] Node Card I/O device found on connection nn messages for each device connected to the I/O Devices connector

Node Card Testing (Using Serial Monitor Testing Program)

This table provides step-by-step instructions to verify the Node Cardā€™s communication interfaces and I/O DEVICES functionality using the serial monitor testing program. Follow each test in sequence, and check ā€œExpected Resultā€ to confirm each testā€™s success.

Test Description Pre-Reqs Action Expected Result
Verify Testing Firmware 1. Upload the ā€˜Testingā€™ firmware to the ESP32.
2. Attach power supply to any power input.
3. Insert DevKit-C Module (U2),
ensuring the USB connection faces the right
edge of the PCB.
4. Attach ESP32 to computer using USB cable.
5. Open serial console, set the port (e.g., COM3) and baud rate (115200).		 Enter m in the serial console input and send. Main Menu - LCC Fusion Project is displayed in the serial console.
Verify NODE BUS I2C Communications (BUS A and BUS B) 1. From the main menu,
select Node Management by entering 1.
2. Choose Device Testing Management.
3. Select Test Node Card Connectivity.		 1. Connect NODE BUS tabs, SDA0 and SCL0 with a jumper wire.
2. Enter c to start the test.
3. Repeat by connecting a jumper wire to
NODE BUS tabs, SDA1 and SCL1
and entering c to start the test again.		 Displays I2C Continuity Test Successful message.
Verify NODE BUS CAN Communications After completing both I2C tests 1. Connect NODE BUS CAN-H and CAN-L
(PCB bottom)
with a jumper wire.
2. Enter c to start the test.		 Displays CAN Continuity Test Successful message.
**Verify I/O DEVICES Connectivity To Devices ** After CAN test completion 1. Attach a multimeter or LEDs to I/O DEVICES
pins 1-8 and NODE BUS GND.
2. Enter c to start test. Each pin will sequentially
go HIGH (3.3 V) for 0.5 sec, repeating until s is entered.		 Multimeter reads 3.3 V or LEDs light up, one at a time.

Troubleshooting

Appendences

Specifications

Specifications for the Power-CAN Card include:

When using multiple Node Cards or Quad-Node Cards, consider using ATX, terminal, or DC-005 barrel connector to provide 5V @ 3A to the Node Bus Hub.

Print
Characteristic Value
I/O LinesĀ (direct connection) 8
Nodes: Max number of Nodes (assuming 100 mA avg per Node ESP32) 30
Node Cards: Max number of Node Cards per Node Cluster 21
Input: Max supply voltage (limit of TVS Diode, SMBJ18 V) 28 V
Input: Max supply current via CAN Bus network cable (limited by network cableā€™s 2 combined power wires) 1.2A
Input: Max supply current via ATX 5557, Spring/Screw Terminal Connector, or DC-005 connector 3A
Input: Max supply current USB-C connector 2A
Output: Max 3V3 output current (LM1117-3V3 regulator limitation) 800 mA
Output: Max supply current to output ATX 5557 or Spring/Screw Terminal connectors 3A
Output: Max 5V output current to Node Bus Hub 3A2,3
Output: Max 12 V to the Node Bus Hub (L7812 regulator limitation) 1.5A4,5
Output: Max output current via USB-C 2A
Output: Max output voltage to ATX 5557 or Spring/Screw Terminal Connector Input Voltage minus ~0.4 - 1.7 V6
  1. Limit of Node Bus Hub (3A) within the Node Cluster (one or more Node Bus Hubs connected together via pin headers)
  2. The LM2596-ADJ switching regulator has a maximum current rating of 5A, but the output is limited to 3A due to:
    • PCB traces (54 mil width), Vias (0.6mm holes), Diodes (SS310), and
    • 3A polyfuse (resettable).
  3. The 5V switching regulator (LM2596-ADJ) operates with approximately a 10% efficiency loss, meaning the input current may exceed the output current by this margin.
  4. Limit of 1.5A by 12 V voltage regulator (L7812CV).
  5. The 12 V linear regulator (L7812) dissipates power as heat, resulting in an efficiency of around 85% (or ~15% efficiency loss), meaning the input current may exceed the output current by this margin.
  6. Voltage drop is caused by reverse voltage protection (two SS310 diodes in series)

Below is an updated version of your Node Card documentation with an additional Indicators & Additional Features section covering the requested items.

How It Works

The Node Card supports both power distribution and CAN network connectivity across LCC Fusion devices. It connects to the Node Bus Hub and enables stable power and reliable communication between multiple Node Cards and I/O modules. Key protections against network fluctuations and reverse voltage are built in; see Protection for more.

CAN Network

The Node Card includes connections to the CAN Network for communications with other LCC protocolā€“enabled devices. Both network cable or 2/3-wire connections are supported.

The 2/3-wire connection could be use to connect with other LCC CAN enabled devices or to a (isolated) CANable Module connected to a computer for use with JMRI.

Correct termination of the CAN network is essential for reliable data transmission. To meet this, the Node Card and Quad-Node Card support auto-termination by detecting low voltage on the CAN network and applying a 120ā€Æ Ī© pullup resistor as needed.

Power Supplied to Local and Remote Node Bus Hubs

The Node Card provides regulated power to both local and remove Node Bus Hubs, with various connection and regulation options (see Protection and Connections for more details):

Remote Node Bus Hub: In addition to using the Node Cardā€™s Node Bus (edge) connection to a Node Bus Hub, you can also link the Node Card to a separate (remote) Node Bus Hub for extended network coverage using a network cable.

  1. The L7812CV regulator converts the supply voltage to 12 V for use by both the Node Card and the Node Bus Hub.
  2. A LM2596-ADJ switching regulator provides a steady 5 V supply for the Node Bus Hub.
  3. A LM1117-3V3 linear regulator supplies 3.3 V to the Hub, meeting the lower voltage requirements of certain modules.
  4. Overcurrent protection is provided by two resettable polyfuses rated at 1.5A and 3A.
  5. Reverse polarity protection is included via a diode across all input lines.
  6. Reverse current protection is included via diodes on each output line.
  7. Noise filtering is implemented with capacitors on both input and output lines to stabilize and clean the power signal.

Multiple Power Inputs/Outputs are supported via voltage regulators:

  • 5 V USB-C (input or output)
  • 12 V output
  • Power input via CAN bus network cable, ATX connection, or USB-C cable. Input power overload is protected using both slow and fast-blow fuses. A fuse holder allows the replacement of fast-blow fuse, which can also be bypassed using a Jump Cap.
  • Battery Backup: An optional Battery Card can provide uninterrupted power, letting the Node Card continue operation if the main supply is lost.

This modular design also supports adding multiple Node Cards to a single Node Bus Hub to expand both power capacity and CAN connectivity, enabling flexible scaling for complex automation configurations.

Indicators & Additional Features

  • Power Indicators: Onboard LEDs for 3.3 V, 5 V, and 12 V rails let you quickly verify that each voltage is active and within spec. A blown fuse indicator circuit also provides a visual alert if a the fast-blow fuse trips.
  • Alert Buzzer & LED: Firmware can drive a buzzer and an additional LED to signal warnings or errors. The number of buzzes or LED blinks can be used as a diagnostic code for troubleshooting.
  • CDI Reset & Node Reboot: The Node Card firmware supports the use of the Node Cardā€™s tactile buttons for triggering a CDI parameter reset or rebooting connected devices, ensuring you can remotely recover or reconfigure nodes if needed.
  • I/O Devices: the ESP32 supports connecting analog, digital, touch, and PWM devices such ase sensors, actuators, or other I/O modules for local or distributed automation tasks.

Connections

Component Designator Connector Label Connector Type Connection Number Function Description
Ā  NODE BUS Card Edge 1-12 Power, Communications Connection to Node Bus Hub
J1 PWR IN USB-C1 V+, GND Power In Connection from Power Supply (14-28 V, 0.5-3A)
J2 PWR IN ATX 5557 RA2 V+, GND Power In Connection from Power Supply (14-28 V, 0.5-3A)
J3 PWR IN DC-0051 V+, GND Power In Connection from Power Supply (14-28 V, 0.5-3A)
J4 PWR OUT ATX 5557 RA V+, GND Power In Connection to next Power-CAN Card, or Node Card (14-28 V, 0.5-3A)
J5, J6 CAN BUS RJ45 Socket 1-8; CAN-H, CAN-L, GND, undef, undef, GND, GND, V+ Power & CAN In/Out Connection to/from other LCC Nodes. Pin 1 pad is square (left side, front row).
J7 I/O RJ45 Socket 1-8 I/O (Digital, ADC, Touch, PWM) Connection to input / output devices, or LCC Fusion breakout boards
J8 NODE BUS RJ45 Socket3 1-8; 3V3, 5V, 12 V, GND, SDA0, SCL0, SCL1, SDA1 LCC Fusion Node Bus connection Connection to LCC Fusion Node Bus Hub
J9 5 V OUT USB-C 5V, GND Power Out Connection to 5V devices (e.g. RPI)
J10 SPI / MICRO-SD MODULE 6-Pin Header SPI (3V3, CS, MOSI, CLK, MISO, GND) SD Card Reader Used for local storage
J11 CAN I/O4, 5 3-Pin Header CAN (CAN-H, CAN-L) CANable Device/Adapter, CAN Network Used to connect to the CAN Network
J12 BATT IN 2P JST XH, screw/spring terminal 12 V, GND Battery Card Connection to LCC Fusion Battery Card for power backup
J13 I2C Display 4-Pin Header GND, 3V3, SCL, SDA Display Monitor Connection to display messages on monitor
  1. Recommend a laptop power supply with a USB-C and DC-005 connectors with typically provide 18-20 V and >3A (>65W) for less than $20 on Amazon.
  2. Recommend using train layout accessory bus which is typically >12 V. If installed, replaces USB-C (J1) and DC-005 (J3) connections.
  3. Typically used to connected to a remote Node Bus Hub (board) as an alternative to using the NODE BUS edge connection to directly connect to a local Node Bus Hub. Pin 1 pad is square (left side, front row).
  4. Provides an alternative method of connect to the CAN Network. A CANable adapters attach to computers via USB.
  5. This connection does NOT provide a galvanic isolation link to the CAN Network for a electrical isolation between the CAN Network and LCC Fusion devices. For protection, insure that the CANable Adapter provides the required isolation.

Protection

The LCC Fusion Node Card is equipped with several protection components to ensure reliable operation and safeguard against electrical faults. Below is an overview of each protection element integrated into the LCC Fusion Node Card and its role:

Hereā€™s the updated row for low voltage detection, noting the minute-based alerts triggered until a reboot:

Print
Protected Component Protection Component Function Specifications Location
Entire Board (Relays, Devices, Voltage Regulator) Crowbar Diode, Resettable Fuse Crowbar Protection protects against reverse polarity by short-circuiting the power supply when connected backward, blowing the fuse to protect the circuit Diode becomes forward-biased if reverse polarity occurs Across the power supply input (ACC V+ to ACC GND) C V+ to ACC GND)
Entire Board (ESP32, Devices) Low Voltage Detection Circuit Monitors 3.3 V rail for voltage drops below 3.0 V, triggering an alert message and buzzer every minute until reboot to prevent brownout conditions that may cause instability Voltage threshold set to 3.0 V ADC pin connected to the 3.3 V output from onboard regulator
Entire Power-CAN Card Fast Blow Fuse Protects from current overflow Hold Current: 3A In series with the incoming Vcc line
Entire Power-CAN Card Polyfuses Protects from sustained overcurrent conditions by increasing resistance when the 3V3 or 5V current exceeds 1.5A. Resets once the fault condition is cleared. Hold Current: 1.5A In series with the 5V, 3V3 output lines
Entire Power-CAN Card TVS Diode SMBJ18A Protects from high-voltage transients by clamping voltage spikes, pthem from reaching sensitive components. Stand-off Voltage:Ā 28 V
Clamping Voltage: 29.2 V		 Across the incoming Vcc and GND lines
CAN Bus Automatic Termination Provides proper termination to prevent signal reflections on the CAN bus. Value: 2x 60 Ī©s in series (120 Ī©s) Across CANH and CANL lines, automatically applied based on CAN network voltage while using a low-pass filter to measure peak voltage.
CAN Bus ESD Protection Diode PESD1CAN Protects the CAN bus lines from electrostatic discharge and voltage spikes. Reverse Stand-off Voltage (Vr): 24 V
Clamping Voltage (Vc): 40 V		 Across CANH to GND and CANL to GND
CAN Bus Line Series Damping Resistor Slows edge-rates and dampens reflections on long CAN bus runs (>100 mm), improving signal integrity. Value: 47 Ī© (1206) In series with CAN lines at theĀ  SN65HVD233DR transceiver pins
I2C Bus Line Series Damping Resistor Slows edge-rates and dampens reflections on long IĀ²C runs (>100 mm), improving signal integrity. Value: 47 Ī© (1206) In series with SDA and SCL at theĀ  ESP32ā€™s I2C pins
I2C Bus (each set) ESD Protection Diode PESD1CAN Protects the CAN bus lines from electrostatic discharge and voltage spikes. Reverse Stand-off Voltage (Vr): 24 V
Clamping Voltage (Vc): 40 V		 Across CANH to GND and CANL to GND
CAN Bus BLM31PG121SN1L Ferrite Beads CAN Network Bus Data Line Noise Suppression Ferrite Bead Ā  In series with the CAN network lines
I2C Bus (each set) BLM31PG121SN1L Ferrite Beads CAN Network Bus Data Line Noise Suppression Ferrite Bead Ā  In series with the I2C network lines
ESP32 Vcc Decoupling Capacitor Filters out high-frequency noise and transient voltage spikes from the power supply, ensuring stable voltage for the ESP32. Value: 0.1 ĀµF, 10uF ceramic Integrated into DevKit-C Board
LM2596-ADJ Regulator Output Capacitor Filters out high-frequency noise and transient voltage spikes from the output, ensuring stable 5V regulation. Value: 680 ĀµF electrolytic Across the output (5 V) and GND
L7812CV Regulator Output Capacitor Filters out high-frequency noise and transient voltage spikes from the output, ensuring stable 12 V regulation. Value: 10 ĀµF ceramic Across the output (12 V) and GND
Ground Bus 48mil Ground Bus Provides a low-resistance path for all protection components, ensuring effective grounding and noise suppression. Width: 48 mil Used by all protection components

Summary

These protection components work together to safeguard the LCC Fusion Node Card from various electrical faults. The CAN termination resistor ensures proper signal integrity on the CAN bus, while the ESD protection diodes protect the CAN bus and I2C lines from voltage spikes and electrostatic discharge. The decoupling capacitor filters out noise and transient voltage spikes, ensuring stable power for the ESP32. The ferrite bead suppresses high-frequency noise on the I2C lines. The input Vcc is protected by the Power Module, which includes a polyfuse and TVS diode for overcurrent and overvoltage protection. Together, these components ensure the LCC Fusion Node Card operates reliably in a potentially harsh electrical environment.

Flow of current 

  flowchart TD;
  powerout["POWER OUTPUT <br/>(Input Power @3A)<br/> (ATX 5557)"];
  cannetwork["CAN Network"];
  subgraph nodecard ["LCC Fusion Node Card"];
 	  subgraph powerinput ["Power Supply Input Connectors"];
 		  direction LR;
      canbus["CAN BUS <br/> (Network Cable, RJ45 Socket)"];  
      usb["USB </br> (USB-C Cable, USB-C Connector)"];
      atx["ACC BUS, or </br> Node Card <br/> (2x wires, ATX 5557 Socket)"];
      battery["Battery <br/> (2x wires, JST XH Socket)"];
    end;
    subgraph piprotection ["Input Protection"];
    	canbus --> |"1.5A, >14 V"| fuse3a["Fuse </br> Fuse Hold with fast blow <br/> (1808 3A )"];
    	usb --> |"3A, >14 V"| fuse3a;
    	atx --> |"3A, >14 V"| fuse3a;
    	battery --> |"12.6 V"| fuse3a;
      fuse3a --> tvs["TVS Diode </br> (SMBJ18A)"]; 
      tvs --> fuse1.5a["Fuse </br> Resettable <br/> (1.5A)"];
      fuse1.5a --> crowbar["Reverse Polarity <br/> Crowbar Diode <br/> (SS310)"];
      cannetwork --> esd["Electrostatic Discharge Protection (ESD)<br/> (PESD1CAN)"];
    end;
    subgraph regulators ["Power Output Voltage Regulators"];
      crowbar --> vs["Voltage Selector <br/> (12 V, or >14 V)"];
      vs -->  regulator12V["Voltage Regulator <br/>(LM7812, 12 V @1.5A)"]; 
      crowbar --> regulator5V["Voltage Regulator <br/> (LM2596-5, 5V @3A)"];
      regulator5V --> regulator3V3["Voltage Regulator <br/> (LM1117-3 V, 3V3 @1.5A)"];
      subgraph diodes ["Reverse Current Protection <br/> (SS310 (5x))"];
    	end;
  	end;
    regulator5V -->  |"5 V"| diodes;
    regulator3V3 -->  |"3V3"| diodes;
    crowbar --> |">14 V @3A"| diodes;
    regulator12V -->  |"12 V"| diodes;
    vs -->  |">14 V"| diodes;
    regulator3V3 -->  |"3V3"| can["CAN Transceiver <br/> (SN65HVD233)"];
    regulator3V3 -->  |"3V3"| vcic["Voltage Comparator <br/> (LM393 IC)"];
    regulator3V3 --> |"3V3"| sdcard["SD Card Reader"];
    regulator5V -->  |"5 V"| esp32["MCU <br/> (ESP32 Module)"];
    diodes --> powerout;
  end;
  subgraph hub["LCC Fusion Node Bus Hub"];
    diodes -->  |"5 V"| hub5V["5 V Power Bus <br/>(5 V @3A)"];
    diodes --> hub3V3["3V3 Power Bus <br/>(3 V @1.5A)"];
    diodes --> hub12V["12 V Power Bus <br/>(12 V @1.5A)"];
  end;
  subgraph iocards["LCC Fusion Cards"];
    hub12V --> |"12 V, or >14 V @1.5A"|turnout["Motors <br/>(switch machine)"];
    hub12V --> |"12 V, or >14 V @1.5A"| led["LED"];
    hub5V --> |"5 V @3A"| LED;
    hub5V --> |"5 V @3A"| quadnodecard["ESP32 <br/> (Quad-Node Card <br/>Sound Card, etc.)"];
    hub3V3 --> |"3V3 @1.5A"| ics["IC <br/> (MCP23017, etc.)"];
    powerout --> |">14 V @3A"| nodecard2["Node Card"];
  end;
  subgraph hub2["Node Bus Hub <br/> Network Cable"];
  end;
diodes --> |"5 V"| hub2;
diodes --> |"3V3 @1.5A"| hub2;
diodes --> |"12 V @1.5A"| hub2;
usbout["USB Devices <br/> (USB-C Cable)"];
diodes -->  |"5 V @3A"| usbout;
hub <--> hub2;

classDef lSalmonStyle fill:#FFA07A,stroke:#333,stroke-width:2px,font-size:24px;
class nodecard lSalmonStyle;
classDef lightGrayStyle fill:#d3d3d3,stroke:#333,stroke-width:2px,font-size:24px;
class hub,hub2,iocards lightGrayStyle;

References

  1. ESP32 DevKitC Module - 38Pin ESP32 DevKitC with ESP32-WROOM-32D

  2. Node Card Firmware configuration:

    1. CAN bus @ 125kbs (per the NMRA LCC standard)
    2. SPI bus @ 4MHz
    3. NOTE: ESP32 PSRAM (SPIRAM) can not be used because pin conflicts with CAN bus (pin 5), I2C bus 1 (pin 18), and SPI (pins 19 and 23)
    4. Node Card ESP32 Pin Assignments
Node Card Function GPIO Pin Ā  Node Card Function GPIO Pin
CAN TX 4 Ā  CAN RX 5
I2C SDA0 (BUS 0) 21 Ā  I2C SCL0 (BUS 0) 22
I2C SDA1 (BUS 1) 18 Ā  I2C SCL1 (BUS 1) 25
SPI CS 17 Ā  SPI SCK/CLK 26
SPI MOSI 23 Ā  SPI MISO 19
NODE REBOOT EN/PU Ā  CDI RESET 36
LOW 12 V VOLTAGE DETECTION 39 Ā  LOW 3V3 VOLTAGE DETECTION 34
IO Pins 1-4 (Digital, ADC, PWM) 2, 12, 15, 14 Ā  IO Pins 5-8 (Digital, ADC, PWM) 13, 27, 32, 33
IO Pins (Touch Pads) T2, T5, T3, T6 Ā  IO Pins (Touch Pads) T4, T7, T9, T8
Flash Pins (reserved) 6, 7, 8, 9, 10,11 Ā  UART0 (reserved) 1, 3
Active Buzzer 35 Ā  Not Used (Input/Output) 0
Last updated on: May 10, 2025 © 2025 Pat Fleming