Traktor Compliant MIDI Controller Project - Part 1

For my next project this is something I have wanted to build for a while now. A Trakor compatible midi controller. For those who have no idea what Traktor is its a professional digital DJing application from Native Instruments. Now it operates perfectly fine when using your computers keyboard or mouse but it really comes alive when using an external midi controller such as native instruments own Traktor Kontrol X1 or DJ Tech Tools MidiFighter Pro.

Traktor Kontrol X1

MidiFighter Pro

Now both of these controllers are excellent controllers in their own right but are a) expensive and b) don’t offer the full flexibility of features I would like to have at my finger tips. Solution build your own!

Now traditionally midi devices where connected using 180° five-pin DIN connectors communicating over a twisted pair plus ground configuration. From what I can remember these are current driven and optically isolated to avoid interference between instruments. However luckily the USB audio class supports USB midi devices which makes things a whole lot simpler. All I need is a microcontroller with USB host support and that’s it. In theory.

A while back I purchased a couple of these MinimusAVR boards (made famous by people jail breaking their PS3s).

These things are amazing. For about a £5 you get a small PCB populated with an Atmel AT90USB162 microcontroller and a few bits of extra hardware, a couple of LEDs and a couple of switches. The AT90USB162 has 16KB of flash, 512 bytes of RAM and 512 bytes of EEPROM. But most importantly

it has a full speed USB transceiver on board as well. Perfect. It even has a small bootloader pre programmed that allows you to reprogram it without the need for an external programmer.

The MinimusAVR will form the basis of this project with the additional hardware fitting around it. Now I know there is a complete USB stack for the USB AVR microcontrollers written by a chap named Dean Camera called LUFA which supports numerous USB classes including MIDI. Check out his website.

My plan is to develop a stand alone midi controller with the following features :-

1. Fully USB compliant.
2. Support for up to 32 digital inputs (push buttons and rotary encoders).
3. Support for 8 analogue inputs (for potentiometers).
4. Support for up to 32 LEDs.
5. Configurable button mapping.
6. Possibly some form of display.
7. Whatever else I can think of as the project progresses.

The project will be broken down and completed in stages :-

First implement a virtual serial device using LUFA. That way communication to and from the microcontroller can be carried out using some form of terminal emulation such as Hyperterminal, TeraTerm or Putty. This will help with debugging during the early stages of getting the hardware working. Messages will be sent to and from the device and once everything is working the virtual serial device will be removed and replaced with a MIDI device instead.

Next add hardware/firmware for reading up to 32 digital inputs. Push buttons switches and rotary encoders. Then add hardware/firmware for driving 32 LEDs. Then hardware/firmware for reading 8 analogue inputs. Possibly some form of display not sure yet. Then once all the hardware is working convert the serial messages into appropriate MIDI messages.

My Weecade - Xbox Based Arcade Machine - Part 8

Wasn't entirely happy with the plain old boring marquee I had originally fitted so I decided to upgrade it. It now has this lovely TRON classic retro 10" backlit marquee header supplied by my favourite sticker seller on eBay. The sticker is sandwiched between two sheets of 3mm clear acrylic. The bottom sheet being painted back with a clear window underneath the sticker allowing light to be shone through. Back lighting is provided by a strip of 30 white LEDs. Its not the brightest but its more than adequate.