kopia lustrzana https://github.com/kosme/arduinoFFT
121 wiersze
4.0 KiB
C++
121 wiersze
4.0 KiB
C++
/*
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Example of use of the FFT library
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Copyright (C) 2014 Enrique Condes
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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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/*
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In this example, the Arduino simulates the sampling of a sinusoidal 1000 Hz
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signal with an amplitude of 100, sampled at 5000 Hz. Samples are stored
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inside the vReal array. The samples are windowed according to Hamming
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function. The FFT is computed using the windowed samples. Then the magnitudes
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of each of the frequencies that compose the signal are calculated. Finally,
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the frequency with the highest peak is obtained, being that the main frequency
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present in the signal. This frequency is printed, along with the magnitude of
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the peak.
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*/
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#include "arduinoFFT.h"
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arduinoFFT FFT = arduinoFFT(); /* Create FFT object */
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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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const uint16_t samples = 64; //This value MUST ALWAYS be a power of 2
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const double signalFrequency = 1000;
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const double samplingFrequency = 5000;
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const uint8_t amplitude = 100;
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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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double vReal[samples];
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double vImag[samples];
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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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Serial.begin(115200);
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while(!Serial);
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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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/* Build raw data */
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double cycles = (((samples-1) * signalFrequency) / samplingFrequency); //Number of signal cycles that the sampling will read
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for (uint16_t i = 0; i < samples; i++)
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{
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vReal[i] = int8_t((amplitude * (sin((i * (twoPi * cycles)) / samples))) / 2.0);/* Build data with positive and negative values*/
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//vReal[i] = uint8_t((amplitude * (sin((i * (twoPi * cycles)) / samples) + 1.0)) / 2.0);/* Build data displaced on the Y axis to include only positive values*/
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vImag[i] = 0.0; //Imaginary part must be zeroed in case of looping to avoid wrong calculations and overflows
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}
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/* Print the results of the simulated 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(vReal, samples, FFT_WIN_TYP_HAMMING, FFT_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(vReal, vImag, samples, FFT_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(vReal, vImag, samples); /* Compute magnitudes */
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Serial.println("Computed magnitudes:");
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PrintVector(vReal, (samples >> 1), SCL_FREQUENCY);
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double x;
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double v;
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FFT.MajorPeak(vReal, samples, samplingFrequency, &x, &v);
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Serial.print(x, 6);
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Serial.print(", ");
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Serial.println(v, 6);
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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(double *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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double 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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