This is my first blog post on Element 14. I have recently completed a small electronics project and wanted to share it with anybody who may wish to make on of their own. But first some background....
What is QLab?
Any Mac user with a reasonable footing in theatre sound production has probably heard of QLab already. For those who haven't it is an application that allows you to control music and/or video for live productions. There is also a great deal of integration possibilities for advanced show control. More information about QLab can be found here: Figure 53 | QLab | Live Show Control for Mac OS X
Why this project?
I was approached by a colleague a few months ago who who had seen an online tutorial for creating a QLab remote from a dismantled keyboard. The membrane was connected to buttons that were used to simulate keypresses that activated hotkeys within the software. We immediately thought that we could do something more elaborate. After a brief initial consideration of using an Adafruit Trinket to emulate keyboard presses we changed the design entirely and decided to use MIDI instead.
MIDI Control
The free edition of QLab allows remote control via MIDI. The primary advantage of MIDI is that the activation of cues would no longer be dependent on the application having "focus". We looked into reprogramming the Trinket to output MIDI and then employed a MIDI to USB convertor with mixed results. This was mostly due to the quality of the usb device.
What we really needed was native MIDI over USB support which the trinket (while capable of performing keyboard emulation) did not appear to support, and so we looked into alternative micro-controllers.
The Teensy 3.1
PJRC had recently released version 3.1 of their Teensy Development Board and a quick investigation indicated that it was capable of outputting MIDI over USB. Full details of the USB MIDI capabilities can be found here: https://www.pjrc.com/teensy/td_midi.html
The Build
Our intention was to keep the unit as simple to operate as possible. After a fair bit of consideration a design featuring only three buttons was created. These give the operator the ability to 'Go', 'Panic' (Stop), and advance down to the next cue. This was added so that unnecessary cues (such as fades) could be skipped if required.
We elected to use some heavy duty LED backlit buttons from Arcade World, in addition to being virtually bullet proof, we were also able to insert legends indicating the function of each button.
Full build details are available in Part II QLab MIDI Controller - The Build.