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Intro - Elliot Tanner - PlectralEFFECTS

Former Member


I am musician, and a full-time Software Developer with over 15 years experience designing and building software solutions!  I am also a hardware junkie, and quite often can be found tinkering with old 8-bit computer systems.

 

Here is an example of a previous project, presented at Syntax 2012 :  SID Sampler

 

https://www.youtube.com/watch?v=TAWcYjHWi3g

 

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Looking forward to getting started!

 

 





PlectralEFFECTS




Overview

 

The goal of my project is to produce a tool for guitarists to vastly enhance the guitar experience for their guitar by providing effects expression and control through the plectrum.

 

The guitarist will be able to "trigger" effect based upon pluck direction to create unique playing styles, not previous possible.

 

 

 

Technical Overview

 

These DSP type effects will be generated by the Beagle Bone Black in realtime by making use of the unique Programmable Realtime Unit(s).  This will require the production of C code to process audio data in realtime from ADC to DAC/HDMI.

 

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Realtime DSP Processing

 

The methods to produce realtime Digital Signal Processing effects is well documented and available to port to the Beagle Bone Black.  The types of effects can include Chorus, Delay, Phasing, Tremolo, Distortion, Compression and Filtering.  The BBB contains two Programmable Real-time Unit Subsystems.  These programmable real-time units allow the creation of real-time applications, whilst still allowing the simultaneous operation of the core processor, for operating system functionality.

 

 

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Code Composer Studio will be used to target the PRU.  I will initially be implementing a real time band-pass filter effect

 

 

 

 

Input Control

 

The main input control for my purpose will be the plectrum Piezo transducer, this will be analyzed in mealtime to determine the direction of pluck / strum.  ie. Up / Down direction.

 

  • 1) In one incarnation of the idea a single Piezo transducer is used to determine the amplitude phase direction to determine the strum direction.

 

  • 2) In another incarnation, two (2) Piezo transducers are used to determine the direction of strum.

 

 

 

image

 

 

Hardware Design

 

I plan to create a custom PCB for the audio input output connects and plectrum (piezo transducer).    Eagle will be used for the hardware design.

 

 

 

I believe that there are risks to the project, like for example :

 

  • The parts and components not working as expected
  • Development time
  • Bugs

 

 

Thanks again!

  • This is a great idea - I can't wait to see how it comes out.

     

    Also, just a thought, but if you find the piezo transducers on the plectrum don't give you the desired effect, you could use the inductance sensor evaluation board that comes in your challenger kit (mine just arrived!) provided you used a metal plectrum or added a piece of metal to a regular plectrum.

     

    Good luck!

  • in reply to shabaz

    Hi Shabaz,

     

    I hope to carry out the majority of the real-time processing on a single PRU.  For the sake of obtaining as close to real-time performance as possible, I may look at inputting and outputting data directly from ADC/DAC as the initial step, then take a look at a the performance of various algorithms for the filter as my initial approach.  However, I am focusing mainly on the plectrum at the moment until parts arrive.

     

    An idea I am looking at is using conductive zones, like a high gain touch circuit.  Effectively giving pick areas on the plectrum as selectors.  The selector zone could then enable say a high pass for some section you want to play thinner (like an intro), and then another area on the plectrum might disable the high-pass and some subtle distortion for the main part of the song.

     

    Elliot

  • Interesting project.

     

    I am looking forward to seeing your implementation.

     

    DAB

  • Hi Elliot,

     

    Looking forward to seeing this project evolve!

    Will the PRU handle all processing, or are you planning to run the main processing in the application processor, and offload certain effects (e.g.

    filtering) to the PRUs? Both approaches sound interesting, I was just curious which approach you will try.

    Also, I think the PRU has multiply-and-accumulate instruction capability, so you should get good performance for effects that use filters!