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AudioFrequencyMeter Library for Arduino

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Allows the Arduino Zero and MKR1000 to sample a generic input audio signal and get the fundamental pitch.

License

Copyright (c) Arduino LLC. All right reserved.

This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA

Methods

  • begin(uint32_t ulPin, uint32_t sampleRate) : initialize the ADC to sample ulPin at the chosen sample rate. This process works in interrupt using TC5 to start the sampling process. ADC resolution is set to 8 bit

  • end() : stops the sampling process disabling both the ADC and TC5 and resetting TC5

  • setClippingPin(int pin) : put pin in output to be used as a clipping indicator

  • checkClipping : checks if there is a clipping event (converted value equals to the top or the bottom of the ADC dynamic) and drives HIGH the clippingPin

  • setAmplitudeThreshold(uint8_t threshold) : sets the threshold for which a detected frequency is considered right or wrong. Default is 30

  • setTimerTolerance(int tolerance) : sets the tolerance for which a sampled signal is considered valid. Default is 10

  • setSlopeTolerance(int tolerance) : sets the tolerance for which the slope is valid for the trigger process. Default is 3

  • setBandwidth(float minFrequency, float maxFrequency) : set the range of frequencies for which the detected frequency is valid. Default values for now are 60 Hz - 1500 Hz. This must be improved

  • getFrequency : return the value of the detected frequency if it is above the threshold defined by setAmplitudeThreshold, else -1