CV Interface and Function Generator: Difference between revisions

'''Analog Circuits and Interfaces'''<br />

''Instructor:'' [[Clemens Wegener]]<br/>

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The inspiration for making this device was the old "A-174-1 Joy Stick" Module by Doepfer and the famous Eurorack Interface ES-X series by Expert Sleepers. The reason for our interest in a Joystick as Control element for analog devices is simply the functional advantage its having, meaning the possibilty to tweak 2 Values with 1 Movement. The interest in dc coupled Interfaces like the Expert Sleepers series is obvious. The idea of generating and receiving control voltage in a digital environment on the pc with software like "CV Tools" by Ableton seems to be pretty interesting. Not just for the sake of an easier and accurate way to generate Control Voltage, no also in the sense of communication between devices and softwares. For example, to make generative Computergraphics with Software like Unity, TouchDesigner or Blender and use control voltage from your Modular Synth to control aspects of the generative Video Output. Or the other way around to generate Video Output inside such software through different functions and to use this data also for the generation of sound through Analog Synthesizers. Not to mention feedback loops. So, we think a dc coupled interface that bridges the world of analog and digital without the use of the extremely quality dropping MIDI protocol is a thing that holds a very big potential for many artistically interesting uses.  

Anyway, as dc coupled interfaces appear to be not very common and quite expensive on the market of audio interfaces we wanted to create a similiar device ourself thats able to send and receive analog Signals over USB connection.  

So now, when we got the cv in- and outputs working it was time to get joystick and potentiometers. We just buyed a cheap Joystick and some 10k Potentiometers. In the first place we were disappointed by the Joystick. The accuracy was extremely low and the spring inside the joystick made it even worse for the usage of accurate voltage generation. So we decided to use 2 channels of the external 16 Bit ADC for the YX-Axis inputs for making the joystick more accurate. And we desoldered the Joystick Circuit, drilled a whole inside and took out the spring. Luckily we orded a 5-Pack of Joysticks instead of just one, because 2 Joysticks got broken in this procedure. The third one was working perfect.  

Then we decided to use the whole potential the arduino is giving us with its 6 internal ADC's and connected 4 Knob Potentiometers and 2 Slider Potentiometers to it. These should control different values of our functions on the arduino.  

Though we didn't had much functions written yet, we knew we would make different modes. So we got some LED's (1 blue, 3 red) for indicating different modes and also we took a switch button breakout board for changing modes. Another switch button we had available through the joystick itself, because this one had a push function.  

To not get users confused its important to say that these are global modi, which both work in the same way, no matter which of the following (local) modes is chosen.  

1. Sine LFO <br/>

2. Sample and Hold internal <br/>

3. Simplex Noise <br/>

4. Sample and Hold external <br/>

This circuit is really a raw prototype, so there are many things to mention.  

After that said, we want to name and explain some functionalities we want to add in the future.  

*General

-higher Range of available Speed for Audio Range Modulation Purposes <br/>

*Sample & Hold  

-Interpolation Amount for fading into Smoothed Random

Add new functions:

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* "Quantizator" <br/>

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*Envelopes <br/>