MDRRC-IIIIII is the successor of MDRRC. It is based on a cheap Cortex STM32 board from EBay and some extra components for interfacing to the booster, S88 bus, XPressNet bus and I2C bus. The board can be purchased at Ebay for around €18,-- .. €30,--. (depends on exchange rate of the uro versus US-Dollar). It's including free post and package! from HongKong or China, search for STM32F103RBT6 on EBay. And the diplay comes with it.... For this price it's impossible to create an own hardware with controller and display.. When ordering a baord also order a CH340 USB serial converter, the onboard USB serial converter on the STM32 baord is a "pain in the ass" with Windows 8 / 8.1 / 10.
What has MDRRC-II to offer?

  • Control maximum 70 Locs with DCC and/or Maerklin Motorola - II format. 
  • DCC 14 / 28 / 128 speed steps, MM-II only 14 speed steps.
  • Control accesory decoders with DCC and/or Maerklin Motorola format. 
  • Function F0..F28 for DCC locomotives if supported (F0 is light).
  • Function F1..F4 control for MM-II locs and of course light. 
  • Maximum of 32 S88 units.
  • USB serial communication for use with for example Koploper ,RocRail or iTrain.
  • XPressNet interface (2 connectors with a manual adjustement) for manual control of locs and turnouts with for example a Roco mouse or XMC 
  • With an ENC28J60 module connected to a router the WMC, Z21 app Roco or Roco WLANMaus can be used to control trains and turnouts wireless.
  • Manual control of locomotives, turnouts, accesory decoders by using the touch panel and a pulse switch (pulse switch depends on used options).. 
  • CV programming (read and write, read only with acknowledge circuit) (also with  Roco mouse and Roco WLANMaus).
  • POM programming of locomotive and accesory decoders (also with Roco mouse and Roco WLANMaus) .
  • CV programming with DecoderPro
  • Easy software updates, just an USB cable and a software tool from ST.

!!!!I2C Manual control interface is removed in version 4.4.0!!!!!

MDRRC documentation and software.  MDRRC DownloadMDRRC-II Download

When ordering a STM32 board, search for
STM32F103RBT6 (development board ) with 2.8" TFT-module on EBay (for example) and make sure the board looks IDENTICAL to the board shown in the manual. And don't forget to order a CH340 USB serial converter.

For those who use Linux/Ubuntu, Vollker supplied information how to program the STM32 board with Linux/Ubuntu. In the manual it is described how to setup communications with MDRRC-II and a PC with  Linux/Ubuntu and for example RocRail. Many thanks to Vollker for this information.

It contains:

          • RS232 level interface for connection to a booster.
          • 2 Connectors for XPressNet interface.
          • S88 Interface (S88N without tracksignal!).
          • USB connector (not usable when J3 software version is used). 

In the meanwhile already PCB version 7 is availble. Compared to previous PCB version the 12V is changed to a swithcing type voltage controller and the PCB got somewhat bigger. Firthermore the 6 pin connector previously used for I2C is now avaibale for XPressnet, so two XPressNet devices can be connected.

Price of the PCB is €4 excluding post and package.  

With an additional ENC28J60 network module MDRRC-II is able to communicate with the Roco Z21 app for mobile devices. See manual for more details, picture below is from a test setup I used.

It's also possible to use an Arduino connected to the network and XpressNet bus to work with the Roco Z21 app. See Digital Modellbahn or this Dutch discussion on

Peter created a Python program to change options. For details see Peters info. For questions reagrding this tool contact Peter!!!

HansQ created an interface PCB for MDRRC-II to control the
BNLS/RCU Booster-Hub. See the link for more information! This interface might be a nice alternative for the PCB I created.... If you are interested in the interface sent Hans a message on
MDRRC-II interface PCB    

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