uDMX - tiny bus powered USB-DMX interface

Probably the smallest USB-DMX Interface in the world….


udmx external for Apple Silicon (M1)
udmx external for MacOS Catalina
LXConsole support for uDMX
LXNet2USBDMX support for uDMX
64bit external for Max7 - version 2015-11-09
udmx works with Logelloop
Control the uDMX from within Ableton Live
uDMX on Github
How to update the udmx Firmware
Latest uDMX source code is on Google Code
Control the uDMX from MIDI
uDMX 1.2 released !!
Buy a fully assembled uDMX
Stay informed: Subscribe to the uDMX mailing list
Article: Control uDMX from a web browser




Below are contributions by some uDMX makers/users. We couldn’t test everything - your feedback is welcome.

uDMX in action

We initially developed the udmx for hauert & reichmuth’s interactive installation TRiCKSTR.

What are you using your udmx for? Send us a link and we’ll make a gallery of udmx projects.


There are three pieces of software:

The command line utility is tested under MacOS X 10.4 and Linux, it should compile under Windows as well
Max/MSP binaries are MacOS X only
See the downloadable archive for the commented source code and binaries

To compile the firmware you’ll need avr-libc (see here how to do this on a macintosh)
To compile the Max external you’ll need the MAX/MSP Software Development Kit
and both the Max external and the commandline tool depend on libusb - open source usb library. For MacOS X, the guys over at www.ellert.se have made handy installer packages for libusb, browse their downloads for the most recent package: http://www.ellert.se/PKGS/

uDMX comes with a handy external object for Max/MSP to control dimmers or other DMX equipment directly from Max/MSP:
Max MSP Help file


uDMX is built around a ATMEL ATMega8 microcontroller, very few external parts are used, thanks to Objective Developments firmware only usb driver.
We went for the surface mounted version to keep it as small as possible. It’s a bit a pain to solder by hand, but feasible with lots of patience and not too many drinks the night before.

Very few pins are needed, but unfortunately smaller AVRs don’t have enough SRAM (we need 512 bytes already to buffer the DMX channels) so we have to use at least a Mega8…
The Mega8 is overclocked at 12Mhz, as needed by the usb driver. We power the RS485 transciever directly from the usb bus - it might be a better idea to put in a dc/dc converter and there should be some overvoltage protection.
Ben Suffolk shows how it could be done with his bus powered USB-DMX Interface

There is a 5pin XLR connector for the DMX and the cable of a dead mouse wired directly to the board for USB. D+ is connected to INT0 and is used by the usb-driver, D- on INT1 permits to check regularly if the usb bus is still alive, put the processor into powersave mode when its not, and wake it up again on any bus activity.

Version History


Building and using uDMX is AT YOUR OWN RISK.
uDMX draws all its power from the host computer’s USB bus and the DMX and USB lines aren’t galvanically isolated. It may destroy your computer, or worse…
Use at your own risk or don’t use it at all!
And read the license…


uDMX is © 2006 [ a n y m a ] - Max & Michael Egger
AVR-USB - firmware-Only USB driver is © Objective Development

Schematics and software are licensed under GNU GPL 2.0;
you can redistribute it and/or modify it under the terms of the
GNU General Public License as published by the Free Software Foundation;
either version 2 of the License, or (at your option) any later version.

uDMX is released in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this document; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.


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