Digital Command Control

Digital Command Control is a way of controlling model railway. Standard was established by NMRA. Latest versions include controlling trains and accessories and feedback from trains to the control stations.

Many devices are available from different manufacturers, however cost is high.

I will try to implement own DCC control using microcontrollers and available parts.

To control the layout I will need power supply, booster, command station, loco decoders, accessories decoders, busy detectors and a communication module for PC.

• Loco Decoder - speed, direction and acceleration management with functions of adjusting lights, playing sounds and controlling couplers
• Booster - for converting commands from command station into electrical signals
• Command station - for generating proper commands for locos and accessories, receiving feedback from busy detectors and managing layout against crashes
• PC communication module - to connect command station with PC and program layout management and locos using software interface
• Busy detector - to receive feedback from locos and organize automatic blocking system to prevent crashes
• Accessory decoder - for signals, railway crossings, construction and street lightning, figure movements and etc.
• Function decoder - for other rolling stock, to control lights and coupling

• Research of information. Results are published under Notes section

• None

• Found nice cheap MP3 players to use with Loco Decoder or with Accessory decoder. These are DFPlayer Mini and BY8001-P16. Modules are small, can drive up to 3W speakers, can be connected to MCU. Support spot sound insert feature, but this is achieved by pausing main sound, playing spot insert and resuming main sound.
• Polyphonic modules also do exist, but their size is much larger and price more than 10 times higher. One example is Sparkfun WAV trigger. However this module is open source hardware and can be adapted. PCM5100 DAC chip price is cheap, as well as STM32 microcontroller. Perhaps I should implement loco sound modules using these.
• Some links about DFPlayer Mini:
  • http://www.picaxe.com/docs/spe033.pdf
  • https://forum.banggood.com/forum-topic-59997.html
  • http://educ8s.tv/arduino-mp3-player/
  • https://community.particle.io/t/a-great-very-cheap-mp3-sound-module-without-need-for-a-library/20111
• Links about BY8001-16P:
  • https://forum.arduino.cc/index.php?topic=306442.0
• Universal DCC decoder, that can be used as Loco or Accessory or Function decoder is described fully in Model Railroad Hobbyist March 2017 #85 magazine. Decoder is based on Arduino and cheap additional components to receive power and signals from DCC bus. Also computer controlled Arduino based Command Station with integrated Booster is decribed there. Then the PC communication module is not necessary, since Arduino will act also as that. All the software and firmware used is also open source DCC++ project. I should compare component prices and perhaps redo all the hardware with STM32 chips. Anyway I am not intended to use bare Arduinos and shields and will make own PCBs to reduce size and adapt for my rolling stock shapes and needs.

• DCC library for STM32 MCUs: https://github.com/mrrwa/NmraDcc