Guitar and Bass Tuner Library for Teensy 3.1 v2.0

Software algorithm (YIN) for guitar and bass tuning using a Teensy Audio Library. This audio object’s algorithm can be some what memory and processor hungry but will allow you to detect with fairly good accurcey the fundumential frequencies from electric guitars and basses. You can install this as a normal Arduino Library and will work with the Audio Library, no need to edit the Audio libraries source now.

Many optimizations have been done to the YIN algorithm for frequencies between 29-360Hz. While its still using a brute force method (n²)for finding fundemential frequency f(o) it is tuned to skip tau values that are out of its frequency range and focus mostly on frequencies found in bass and guitar. There a few parameters that can be adjusted to “dial in” the algorithm better use. Te defaults are what I find that have the trade off for speed and accurcy.

In AudioTuner.h you can edit these paratemters:
/****************************************************************
*              Safe to adjust these values below               *
****************************************************************/
// Adjust number of samples to collect in buffer here, also effects
// convergence speed and resolution.
#define NUM_SAMPLES 2048 // make a power of two

// larger the divide-by, less resolution and lower the frequency for
// a given number of samples that can be detected. Also effects
// convergence speed.
#define SAMPLE_SKIP SAMPLE_RATE_DIVIDE_BY_2
/****************************************************************/

  Hookup Guide - 1.2v DC Bias and High Pass Filter - No Amplification

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|2      E     23|    10K        47K     |          |  |` ` ` `|       |
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|4      S     21|                       |          |   \_`_`_/        |
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|6     3.1    19|                       |          |    | S`|         |
|7            18|                       |  REMOVE  |    | H`|         |
|8            17|                       |    DC    |    | I`|         |
|9         A2/16|<---SIGNAL-1.2v-BIAS---*---+|(----*    | E`|>--ANGD--*
|10    ---    15|                     1.2V  10uF   |    | L`|
|11   |(`)|   14|                      DC          |    | D`|
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