kopia lustrzana https://github.com/kosme/arduinoFFT
Original code
Enrique Condes
rodzic
bbbe650f0b
commit
fe030b5583
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/.project
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/*
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Example of use of the FFT libray
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Copyright (C) 2011 Didier Longueville
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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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#include "PlainFFT.h"
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PlainFFT FFT = PlainFFT(); /* 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;
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double signalFrequency = 1000;
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double samplingFrequency = 5000;
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uint8_t signalIntensity = 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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void setup(){
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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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/* Build raw data */
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double cycles = (((samples-1) * signalFrequency) / samplingFrequency);
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for (uint8_t i = 0; i < samples; i++) {
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vReal[i] = uint8_t((signalIntensity * (sin((i * (6.2831 * cycles)) / samples) + 1.0)) / 2.0);
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}
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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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PrintVector(vReal, samples, SCL_TIME);
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FFT.Compute(vReal, vImag, samples, FFT_FORWARD); /* Compute FFT */
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PrintVector(vReal, samples, SCL_INDEX);
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PrintVector(vImag, samples, SCL_INDEX);
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FFT.ComplexToMagnitude(vReal, vImag, samples); /* Compute magnitudes */
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PrintVector(vReal, (samples >> 1), SCL_FREQUENCY);
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double x = FFT.MajorPeak(vReal, samples, samplingFrequency);
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Serial.println(x, 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, uint8_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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double abscissa;
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/* Print abscissa value */
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switch (scaleType) {
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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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Serial.print(" ");
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Serial.print(vData[i], 4);
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Serial.println();
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}
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Serial.println();
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}
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@ -0,0 +1,181 @@
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/*
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FFT libray
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Copyright (C) 2010 Didier Longueville
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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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#include "PlainFFT.h"
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#define twoPi 6.28318531
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#define fourPi 12.56637061
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PlainFFT::PlainFFT(void)
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{
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/* Constructor */
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}
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PlainFFT::~PlainFFT(void)
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{
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/* Destructor */
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}
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uint8_t PlainFFT::Revision(void)
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{
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return(FFT_LIB_REV);
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}
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void PlainFFT::Compute(double *vReal, double *vImag, uint16_t samples, uint8_t dir)
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{
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/* Computes in-place complex-to-complex FFT */
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/* Reverse bits */
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uint16_t j = 0;
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for (uint16_t i = 0; i < (samples - 1); i++) {
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if (i < j) {
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Swap(&vReal[i], &vReal[j]);
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Swap(&vImag[i], &vImag[j]);
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}
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uint16_t k = (samples >> 1);
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while (k <= j) {
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j -= k;
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k >>= 1;
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}
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j += k;
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}
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/* Compute the FFT */
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double c1 = -1.0;
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double c2 = 0.0;
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uint8_t l2 = 1;
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for (uint8_t l = 0; (l < Exponent(samples)); l++) {
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uint8_t l1 = l2;
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l2 <<= 1;
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double u1 = 1.0;
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double u2 = 0.0;
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for (j = 0; j < l1; j++) {
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for (uint16_t i = j; i < samples; i += l2) {
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uint16_t i1 = i + l1;
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double t1 = u1 * vReal[i1] - u2 * vImag[i1];
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double t2 = u1 * vImag[i1] + u2 * vReal[i1];
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vReal[i1] = vReal[i] - t1;
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vImag[i1] = vImag[i] - t2;
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vReal[i] += t1;
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vImag[i] += t2;
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}
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double z = ((u1 * c1) - (u2 * c2));
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u2 = ((u1 * c2) + (u2 * c1));
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u1 = z;
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}
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c2 = sqrt((1.0 - c1) / 2.0);
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if (dir == FFT_FORWARD) {
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c2 = -c2;
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}
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c1 = sqrt((1.0 + c1) / 2.0);
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}
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/* Scaling for reverse transform */
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if (dir != FFT_FORWARD) {
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for (uint16_t i = 0; i < samples; i++) {
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vReal[i] /= samples;
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vImag[i] /= samples;
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}
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}
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}
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void PlainFFT::ComplexToMagnitude(double *vReal, double *vImag, uint16_t samples)
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{
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/* vM is half the size of vReal and vImag */
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for (uint8_t i = 0; i < samples; i++) {
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vReal[i] = sqrt(sq(vReal[i]) + sq(vImag[i]));
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}
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}
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void PlainFFT::Windowing(double *vData, uint16_t samples, uint8_t windowType, uint8_t dir)
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{
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/* Weighing factors are computed once before multiple use of FFT */
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/* The weighing function is symetric; half the weighs are recorded */
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double samplesMinusOne = (double(samples) - 1.0);
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for (uint16_t i = 0; i < (samples >> 1); i++) {
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double indexMinusOne = double(i);
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double ratio = (indexMinusOne / samplesMinusOne);
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double weighingFactor = 1.0;
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/* Compute and record weighting factor */
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switch (windowType) {
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case FFT_WIN_TYP_RECTANGLE: /* rectangle (box car) */
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weighingFactor = 1.0;
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break;
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case FFT_WIN_TYP_HAMMING: /* hamming */
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weighingFactor = 0.54 - (0.46 * cos(twoPi * ratio));
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break;
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case FFT_WIN_TYP_HANN: /* hann */
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weighingFactor = 0.54 * (1.0 - cos(twoPi * ratio));
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break;
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case FFT_WIN_TYP_TRIANGLE: /* triangle (Bartlett) */
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weighingFactor = 1.0 - ((2.0 * abs(indexMinusOne - (samplesMinusOne / 2.0))) / samplesMinusOne);
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break;
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case FFT_WIN_TYP_BLACKMAN: /* blackmann */
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weighingFactor = 0.42323 - (0.49755 * (cos(twoPi * ratio))) + (0.07922 * (cos(fourPi * ratio)));
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break;
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case FFT_WIN_TYP_FLT_TOP: /* flat top */
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weighingFactor = 0.2810639 - (0.5208972 * cos(twoPi * ratio)) + (0.1980399 * cos(fourPi * ratio));
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break;
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case FFT_WIN_TYP_WELCH: /* welch */
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weighingFactor = 1.0 - sq((indexMinusOne - samplesMinusOne / 2.0) / (samplesMinusOne / 2.0));
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break;
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}
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if (dir == FFT_FORWARD) {
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vData[i] *= weighingFactor;
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vData[samples - (i + 1)] *= weighingFactor;
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}
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else {
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vData[i] /= weighingFactor;
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vData[samples - (i + 1)] /= weighingFactor;
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}
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}
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}
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double PlainFFT::MajorPeak(double *vD, uint16_t samples, double samplingFrequency)
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{
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double maxY = 0;
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uint16_t IndexOfMaxY = 0;
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for (uint16_t i = 1; i < ((samples >> 1) - 1); i++) {
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if ((vD[i-1] < vD[i]) && (vD[i] > vD[i+1])) {
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if (vD[i] > maxY) {
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maxY = vD[i];
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IndexOfMaxY = i;
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}
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}
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}
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double delta = 0.5 * ((vD[IndexOfMaxY-1] - vD[IndexOfMaxY+1]) / (vD[IndexOfMaxY-1] - (2.0 * vD[IndexOfMaxY]) + vD[IndexOfMaxY+1]));
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double interpolatedX = ((IndexOfMaxY + delta) * samplingFrequency) / (samples-1);
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/* retuned value: interpolated frequency peak apex */
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return(interpolatedX);
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}
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/* Private functions */
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void PlainFFT::Swap(double *x, double *y)
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{
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double temp = *x;
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*x = *y;
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*y = temp;
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}
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uint8_t PlainFFT::Exponent(uint16_t value)
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{
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/* Computes the Exponent of a powered 2 value */
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uint8_t result = 0;
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while (((value >> result) & 1) != 1) result++;
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return(result);
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}
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@ -0,0 +1,59 @@
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/*
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FFT libray
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Copyright (C) 2010 Didier Longueville
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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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#ifndef PlainFFT_h /* Prevent loading library twice */
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#define PlainFFT_h
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#include "WProgram.h" /* This is where the standard Arduino code lies */
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#define FFT_LIB_REV 0x02
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/* Custom constants */
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#define FFT_FORWARD 0x01
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#define FFT_REVERSE 0x00
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/* Windowing type */
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#define FFT_WIN_TYP_RECTANGLE 0x00 /* rectangle (Box car) */
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#define FFT_WIN_TYP_HAMMING 0x01 /* hamming */
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#define FFT_WIN_TYP_HANN 0x02 /* hann */
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#define FFT_WIN_TYP_TRIANGLE 0x03 /* triangle (Bartlett) */
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#define FFT_WIN_TYP_BLACKMAN 0x04 /* blackmann */
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#define FFT_WIN_TYP_FLT_TOP 0x05 /* flat top */
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#define FFT_WIN_TYP_WELCH 0x06 /* welch */
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class PlainFFT {
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public:
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/* Constructor */
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PlainFFT(void);
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/* Destructor */
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~PlainFFT(void);
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/* Functions */
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void ComplexToMagnitude(double *vReal, double *vImag, uint16_t samples);
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void Compute(double *vReal, double *vImag, uint16_t samples, uint8_t dir);
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double MajorPeak(double *vD, uint16_t samples, double samplingFrequency);
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uint8_t Revision(void);
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void Windowing(double *vData, uint16_t samples, uint8_t windowType, uint8_t dir);
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private:
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/* Functions */
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uint8_t Exponent(uint16_t value);
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void Swap(double *x, double *y);
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};
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#endif
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30
README.md
30
README.md
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@ -4,3 +4,33 @@ arduinoFFT
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Fast Fourier Transform for Arduino
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This is a fork from https://code.google.com/p/makefurt/ which has been abandoned since 2011.
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This is a C++ library for Arduino for computing FFT.
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Tested on Arduino 0022 Alpha.
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Installation
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--------------------------------------------------------------------------------
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To install this library, just place this entire folder as a subfolder in your
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When installed, this library should look like:
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Arduino\libraries\PlainFTT (this library's folder)
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Arduino\libraries\PlainFTT\PlainFTT.cpp (the library implementation file, uses 32 bits floats vectors)
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Arduino\libraries\PlainFTT\PlainFTT.h (the library description file, uses 32 bits floats vectors)
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Arduino\libraries\PlainFTT\PlainFTT_INT.cpp (the library implementation file, experimental signed 16 bits vectors)
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Arduino\libraries\PlainFTT\PlainFTT_INT.h (the library description file, experimental signed 16 bits vectors)
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Arduino\libraries\PlainFTT\keywords.txt (the syntax coloring file)
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Arduino\libraries\PlainFTT\examples (the examples in the "open" menu)
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Arduino\libraries\PlainFTT\readme.txt (this file)
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Building
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--------------------------------------------------------------------------------
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After this library is installed, you just have to start the Arduino application.
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You may see a few warning messages as it's built.
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To use this library in a sketch, go to the Sketch | Import Library menu and
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select PlainFTT. This will add a corresponding line to the top of your sketch:
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#include <PlainFTT.h> (or #include <PlainFTT_INT.h>
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@ -0,0 +1,21 @@
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#######################################
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# Syntax Coloring Map For PlainFFT
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#######################################
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#######################################
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# Datatypes (KEYWORD1)
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#######################################
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PlainFFT KEYWORD1
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#######################################
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# Methods and Functions (KEYWORD2)
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#######################################
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complexToMagnitude KEYWORD2
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compute KEYWORD2
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windowing KEYWORD2
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exponent KEYWORD2
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swap KEYWORD2
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revision KEYWORD2
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majorPeak KEYWORD2
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