Modular DCC micro control unit

The modular DCC microcontroller is an evolution of the minimal micro control unit already fully described on these pages.

The rail network driver is now shared between the computer on which the JMRI software is installed and the Bluetooth joystick module which, after uploading data, can become a stand-alone manager. This branch of the project will enable other complementary modules to be connected, enriching the DCC central unit and offering numerous solutions for controlling the entire network.


The characteristics of this project, all modules combined, are as follows:

  • space-saving assembly;
  • locomotive addressing in short or long addresses;
  • speed in 128 steps;
  • simultaneous control of several locomotives (direction, speed and 29 functions);
  • control of over 2000 accessories via DCC protocol;
  • maximum power supply 4A ;
  • short-circuit protection (DCC power cut-off in the event of over-consumption, to prevent damage to electronics and rolling stock);
  • configuration variable (CV) programming mode selector for one locomotive ;
  • emergency stop button ;
  • restart push-button;
  • possibility of connecting additional units (current measurement, Bluetooth or WIFI control, etc.);
  • locomotive presence detection on the programming section.

      This project covers all aspects related to the creation of a rail network using this modular power plant:

      • electronic circuit assembly ;
      • microcontroller programming (Arduino Nano, AtTiny85 and ESP32);
      • functional testing;
      • installation and parameterization of JMRI software;
      • locomotive parameterization;
      • rail network operation (traction and functions from the controller).

      Maturity : 50%

      Overall project status


      Version 1.0

      This first version of the project will enable the basic modules to be produced. In addition to the main circuit, modules dedicated to current consumption measurement and Bluetooth control will also be available.

      The various DCC microcontroller modules

      Maturity : 80%

      Main module of the modular DCC micro control unit with room for additional modules. Magnetic connectors enable rapid modification of the control unit's configuration.

      Maturity : 50%

      Management of the Bluetooth Low Energy (BLE) joystick, as well as the memorization of the drivetrains, is carried out by fully automated learning thanks to the contribution of an ESP32. All network management in the palm of a single hand!

      Maturity : 40%

      Two devices are available:

      • A simple analog galvanometer measuring instantaneous current consumption. Vintage effect guaranteed...
      • A screen displaying the power plant's overall consumption curve. An AtTiny85 manages measurement sampling and graphic display.

      Design in progress...

      This module provides a detailed view of the selected loco's characteristics (address, direction, speed, active functions) and allows distant vision.

      Technical choices

      The aim of this project is to offer a small-scale DCC control unit that can accommodate additional modules. Each module will add new functionalities to the control unit.

      Here are the choices made during the design of these assemblies and the arguments that led to this solution:

      • use of magnetized connectors, so that the configuration of the control unit can be quickly changed without laborious wiring;
      • an ergonomic, one-handed joystick for all manual network management operations. Virtually all commercial joysticks require two hands for complete operation.
      • no time-consuming parameter setting for each new motor. Use the "say it once" principle.
      • have a stand-alone manager (in addition to the control unit) to control locomotives without using the computer.


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