Saturday, May 2, 2015

A groovebox using Arduino uno (part 1 of N)


it's been a while since I last wrote on this blog. The previous blog entry dates back to 2009. Wow, that was six years ago... In the meantime a lot of things happened. As a citizen of a crisis plagued Greece I witness a whole nation holding its breath hoping for some kind of salvation fearing that an economic apocalypse might happen. As I find breath holding a waste of time, I started a new project that marries two of my favorite interests: Electronics and music. I am an amateur electronic musician and over the years I managed to gather a few sound producing gadgets and software. However, as every synth freak knows, I feel the urge to add new weapons to my sonic arsenal. I already have 2 Virtual Analog Synths (M-Audio Venom, Novation Mininova), and a cheap analog synth (Korg Volca keys). I recently brought back from the attic a yamaha 4 track cassette recorder and the idea of creating songs only with physical hardware, without a DAW and a computer for some reason started to resonate. What I don't have is a drum machine/groovebox hardware that could be used as the rhythm section and the backbone of the songs I write. Of course you can find a lot of grooveboxes and hardware in the market right now. But instead of buying a groovebox or a drum machine, the idea of creating my own groovebox started to grow on me for many reasons. Reason number one is to create something unique sounding with an expressive and creative workflow. As I had one or two arduino unos lying around I thought that I could base my groovebox on arduino. So I started researching and trying to shape the groovebox design in my head. I had to balance the features I wanted with the physical limitations of the parts I had in my disposal for prototyping. After quite some thought I decided on a simple design with the following specifications.
1. Arduino uno based. That means that you can use a lot of existing libraries and resources and integrate rather than write code from scratch and there are a lot of documented ways to create a product out of your prototype.
2. OLED LCD display. I also considered 7 segment type displays or even a color coded led scheme for visual feedback regarding the groove machine. But since I wanted to be able to edit a lot of parameters, some sort of LCD display became mandatory.
3. Rotary encoders. I really like rotary encoders. I think that by using them, instead of potentiometers, is easier and really expressive.
4. 4 sounds at once, in order to be able to create interesting grooves and mini songs. Also some other buttons with shift and/or mode functions.
5. Low fi sound.
6. Low part count and cheap to make.

Little by little I started connecting the various components. Here is the prototype spaghetti of wires that I made.

You can see six buttons. The first 4 switches act as trigger pads and the other two as shift and mode buttons. The screen used is an OLED 0.96" monochrome display that is quite small but really crisp and can be had with only 4.30 euros. The two rotary encoders and the sound output are on the upper breadboard. In the next installments of these series we will take a look on how we could decide on the sound producing library for Arduino. Until then, take care and take a look on the project code on github !

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