Another small project. This time we have a controller that attaches to my audio interface. The interface in question is the RME Fireface 400. A wonderful interface. The front panel which is close by, has only one control on it which is a rotary encoder that allows you to access most of the controls but it is not easy. I wanted a controller which did some basic things - control the speakers level, switch over to the headphone output, dim the audio level and do a mono mix.
This project had some new challenges. The Arduino I have used is the Pro Micro. This is a newer type of Arduino which has the nice feature of a Atmega 32u4 as its USB interface which allows us to use the Arduino as a MIDI device. This avoids the extra hardware for traditional MIDI connection at the computer end and the controller end. The USB also powers the unit. Nice simple single connector for MIDI and power.
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| The wooden knob is a nice feature and the nice thing about jarrah is its strength. |
I wanted to try making a sloped case as well and including my recent(ish) haul of old jarrah floorboards. I got a pile of old floorboards from my father-in-law which were unprocessed. So, I came up with a method of using my CNC router to finish the wood so it could be used for such projects. This takes some time and is a little wasteful but the wood would have been trashed otherwise.
The electronics is quite simple. The switches are individually attached to inputs on the Arduino along with the orange LED and rotary encoder. I've used an USB extender cable which gives us a USB-B socket on the rear of the case. The Pro Micro board's micro USB connector is notorious for coming off!
The software was a little confusing. Like many computer audio interfaces which have MIDI control, there are a few different methods of communication. The one I chose does quite have the options that I have included on the controller. For example the Speaker and Headphones switches are the same code. They're a toggle with the MIDI code instead of a OFF / ON option. It works ok.
