kopia lustrzana https://github.com/kosme/arduinoFFT
124 wiersze
3.8 KiB
C++
124 wiersze
3.8 KiB
C++
/*
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Example of use of the FFT libray to compute FFT for a signal sampled through the ADC
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with speedup through different arduinoFFT options. Based on examples/FFT_03/FFT_03.ino
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Copyright (C) 2020 Bim Overbohm (template, speed improvements)
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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// There are two speedup options for some of the FFT code:
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// Define this to use reciprocal multiplication for division and some more speedups that might decrease precision
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//#define FFT_SPEED_OVER_PRECISION
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// Define this to use a low-precision square root approximation instead of the regular sqrt() call
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// This might only work for specific use cases, but is significantly faster. Only works for ArduinoFFT<float>.
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//#define FFT_SQRT_APPROXIMATION
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#include "arduinoFFT.h"
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/*
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These values can be changed in order to evaluate the functions
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*/
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#define CHANNEL A0
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const uint16_t samples = 64; //This value MUST ALWAYS be a power of 2
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const float samplingFrequency = 100; //Hz, must be less than 10000 due to ADC
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unsigned int sampling_period_us;
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unsigned long microseconds;
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/*
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These are the input and output vectors
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Input vectors receive computed results from FFT
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*/
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float vReal[samples];
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float vImag[samples];
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/* Create FFT object with weighing factor storage */
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ArduinoFFT<float> FFT = ArduinoFFT<float>(vReal, vImag, samples, samplingFrequency, true);
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#define SCL_INDEX 0x00
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#define SCL_TIME 0x01
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#define SCL_FREQUENCY 0x02
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#define SCL_PLOT 0x03
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void setup()
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{
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sampling_period_us = round(1000000*(1.0/samplingFrequency));
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Serial.begin(115200);
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Serial.println("Ready");
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}
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void loop()
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{
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/*SAMPLING*/
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microseconds = micros();
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for(int i=0; i<samples; i++)
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{
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vReal[i] = analogRead(CHANNEL);
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vImag[i] = 0;
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while(micros() - microseconds < sampling_period_us){
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//empty loop
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}
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microseconds += sampling_period_us;
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}
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/* Print the results of the sampling according to time */
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Serial.println("Data:");
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PrintVector(vReal, samples, SCL_TIME);
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FFT.windowing(FFTWindow::Hamming, FFTDirection::Forward); /* Weigh data */
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Serial.println("Weighed data:");
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PrintVector(vReal, samples, SCL_TIME);
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FFT.compute(FFTDirection::Forward); /* Compute FFT */
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Serial.println("Computed Real values:");
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PrintVector(vReal, samples, SCL_INDEX);
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Serial.println("Computed Imaginary values:");
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PrintVector(vImag, samples, SCL_INDEX);
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FFT.complexToMagnitude(); /* Compute magnitudes */
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Serial.println("Computed magnitudes:");
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PrintVector(vReal, (samples >> 1), SCL_FREQUENCY);
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float x = FFT.majorPeak();
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Serial.println(x, 6); //Print out what frequency is the most dominant.
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while(1); /* Run Once */
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// delay(2000); /* Repeat after delay */
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}
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void PrintVector(float *vData, uint16_t bufferSize, uint8_t scaleType)
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{
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for (uint16_t i = 0; i < bufferSize; i++)
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{
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float abscissa;
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/* Print abscissa value */
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switch (scaleType)
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{
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case SCL_INDEX:
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abscissa = (i * 1.0);
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break;
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case SCL_TIME:
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abscissa = ((i * 1.0) / samplingFrequency);
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break;
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case SCL_FREQUENCY:
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abscissa = ((i * 1.0 * samplingFrequency) / samples);
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break;
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}
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Serial.print(abscissa, 6);
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if(scaleType==SCL_FREQUENCY)
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Serial.print("Hz");
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Serial.print(" ");
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Serial.println(vData[i], 4);
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}
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Serial.println();
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}
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