DMX512 Streaming Recorder & RDM Interface – A Concept

This USB device works with one DMX universe. A DMX universe is 512 channels of 256 levels. The device also has a slot for a memory card. Maximum memory card size is 32GB.

The device also works as a streaming recorder. When show is running you can simultaneously save it to memory card and output to DMX512 port. If USB connection is lost during play it rewinds automatically and starts from beginning of saved show.

With 2GB memory card maximum recording time is 4 days! Record is simple series of CSV text files on FAT file system. Starting from first subdirectory with 1.csv and so on. Each subdirectory is separate show.

Changing operating mode and choosing between saved shows can be done with onboard display and button. Display shows simple to understand symbols for recording and playback functions and numbers for choosing between memory slots. By pressing button shortly it blinks current symbol and it is possible to browse through functions. Long press chooses that function and it’s symbol stops blinking.

The device also works as a RDM interface. With compatible software on computer it allows control and monitor RDM fixtures remotely. Currently on Linux there is no any software available.

AVR Program

The device uses AtMega328PB-AUR microcontroller with 16MHz crystal. It includes two hardware serial ports and two hardware SPI port. First serial port is USB interface and second serial port is DMX/RDM interface. Speed on both serial ports must be 250000 baud. First SPI port is used only for programming and second SPI port is used to communicate with memory card. Program is written with C++ language. Microcontroller is programmed using avr-gcc and avrdude. Program is released under GNU General Public License.

This program uses:

  • Enttec DMX USB Pro protocol to communicate with PC.
    API specification:
    Copyright (c) 2007 Enttec Pty/Ltd
  • Parts from DMXSerial and DMXSerial2 libraries.
    Copyright (c) 2011-2013 by Matthias Hertel,
    This work is licensed under a BSD style license. See
  • Parts from SdFat and Sd2Card libraries.
    Copyright (c) 2009 by William Greiman
    GNU General Public License V3.
  • Parts from Arduino SD-library.
    Copyright (c) 2010 SparkFun Electronics
    GNU General Public License V3.
  • CRC-7 routine and CRC-7 table from
    Copyright (c) 2013 Alan Ott
    Copyright (c) 2013 Signal 11 Software
    GNU Lesser General Public License V3.