This Arduino project is a hybrid between analog train operation and digital control. It controls a model train layout with multiple stations, turnouts, motors, and an LCD display. It supports speed measurement, block section management, turnout control, and the display of operational data.

N-scale (1:160) layout with 2 main station tracks (HBF1, HBF2) and 5 staging yard tracks (BBF1–BBF5). Trains run counter-clockwise through 3 electrically isolated zones:

• Zone A – Departure from HBF and BBF area
• Zone B – Arrival into HBF
• Zone C – Outer loop between BBF and HBF

11 turnouts (W1–W11) route trains between tracks. See doc/track-schematic.md for the full track diagram.

• Motor control for 4 independent zones (ZONE_A, ZONE_B, ZONE_C, ZONE_D)
• Block section control with automatic train separation (Zone B and Zone C blocking)
• Speed measurement (cm/s and km/h, scaled for 1:160)
• Turnout control via buttons and servos (11 turnouts)
• Status display on a 20x4 LCD
• EEPROM storage of track states and relay configuration
• Modular structure (Core, Controls, Display, Operation, Utils)

• Arduino Mega compatible board
• MCP4261XX digital potentiometers (2x dual-pot chips for 4 zones, soft SPI)
• PCA9685 PWM servo driver (I2C) for turnout servos
• 74HC165 shift registers for button and reed switch input
• 74HC595 shift registers for relay output
• Reed switches for track monitoring
• 20x4 LCD (HD44780 compatible)
• Rotary encoders (2x, interrupt-driven) for speed control per zone
• Buttons for manual track control
• Relays for track section switching

All relevant pins are documented in src/core/config.h and can be adjusted there.

• Buttons toggle track power and switch turnout positions.
• Reed switches trigger block section logic and measure speed.
• Rotary encoders control motor speed per zone.
• LCD displays selected/powered tracks, encoder values, and speed in km/h.

code/
  code.ino              – Main program (setup, loop)
  src/
    core/               – Configuration, state, enums, initialization
      config.h          – Pin assignments, constants, firmware version
      init.h            – Hardware initialization
      naming.h          – Enums for zones, buttons, reeds, turnouts
      state.h           – Track state struct and route data
    controls/           – Hardware driver modules
      buttonControl     – 74HC165 button input with edge detection
      encoderControl    – Interrupt-driven rotary encoders
      lcdControl        – LCD print with caching and RTL support
      motorControl      – MCP4261XX digital potentiometer control
      reedControl       – 74HC165 reed switch input
      relayControl      – 74HC595 relay output
      servoControl      – PCA9685 turnout servo control
    display/            – LCD layout definitions
      trackDisplay.h    – Track display slot table
    operation/          – Train operation logic
      blockControl      – Zone C blocking and BBF release logic
    utils/              – Utility functions
      debug             – Serial state and EEPROM diff output
      eeprom            – EEPROM load/save with versioned schema
      utils             – Speed measurement, scale conversion, timer

The firmware version (FIRMWARE_VERSION in src/core/config.h) is displayed on the LCD at startup. Versioning follows SemVer.

• Up to 3 trains can run simultaneously on separate zones (ZONE_A, B, C)
• ZONE_D is reserved for future expansion
• Soft SPI is used for motor control (MCP4261XX digital potentiometers)
• The minimum driving speed is limited by the motor characteristics
• The speed is converted to scale, but may be higher than prototype speed due to technical constraints

• Track Schematic – Full track layout diagram
• Arduino Pin Assignment – Complete pin mapping
• Button Shift Register – Shift register wiring for buttons

This project is licensed under the MIT License.