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Topic: VU meter audio signal break up (Read 2796 times) previous topic - next topic

Paranemertes

@Magician, ok got the thing downloaded and opened in arduino, how do i convert it to a library? do i just create a new folder inside the libraries folder and save it there?
"It's Dr. Evil. I didn't spend six years in Evil Medical School to be called 'mister,' thank you very much."

Nick Gammon


To Nick: it's me , who confused this time, which library written for mega? Can you post a link?


Er ... <searches through history> ... this one:

http://elm-chan.org/works/akilcd/report_e.html

In particular:

http://elm-chan.org/works/akilcd/akilcd.zip
Please post technical questions on the forum, not by personal message. Thanks!

More info:
http://www.gammon.com.au/electronics

Magician

#17
Feb 23, 2012, 07:24 am Last Edit: Feb 23, 2012, 07:26 am by Magician Reason: 1
To OP: there is a link:http://www.arduino.cc/en/Hacking/Libraries  and more info in General section:  http://arduino.cc/playground/Main/TutorialList
It's not necessary to create a library, it's only simplify navigation in the huge programs, and doesn't change functionality at all.
To Nick:
Quote
Plus this particular FFT library was written for the Mega,
I thought you mean arduino Mega board, but itr's not the case, as Chan's softaware written for
Quote
The microcontroller is an Atmel ATmega8
which is even smaller uCPU than AtMega328
on arduino Uno.

Paranemertes

OK, so i can just keep this code chillin at the bottom of the sketch? no need to get the .cpp or header file? And could someone please explain in very basic terms how to use this library?!!? thanks
"It's Dr. Evil. I didn't spend six years in Evil Medical School to be called 'mister,' thank you very much."

Paranemertes

one more thing, say i want to turn it into a library, how do i convert the text from the link that has the header and .cpp files into those actual files? right now they are just text...
"It's Dr. Evil. I didn't spend six years in Evil Medical School to be called 'mister,' thank you very much."

Magician

Your questions are saying than you bite more than you could chew at this time. Don't mean to be rude, but you should start from "blinking led" example, than move to 12x24 = 288 "blinking leds" , after that to 288 x 3 (RGB) = 864 ! "... leds", one step at a time, create different visual effect , change pattern of matrix, work on hardware - software interface, and at last step "inject" a DSP sub-function in already build and verified software. Time frame may vary, average 3-6 month.

Coding Badly

#21
Feb 23, 2012, 08:49 am Last Edit: Feb 23, 2012, 08:52 am by Coding Badly Reason: 1
Quote
how do i convert it to a library? do i just create a new folder inside the libraries folder and save it there?


The preferred location is [font=Courier New]SketchBookDirectory\libraries\YourLibraryName\[/font].  For example, my sketches are stored in...
[font=Courier New]C:\Projects\Arduino\Sketch\[/font]

On my computer, "user" libraries go in...
[font=Courier New]C:\Projects\Arduino\Sketch\libraries\[/font]

So a good place for an FFT library would be...
[font=Courier New]C:\Projects\Arduino\Sketch\libraries\FFT\[/font]

In other words, as you suspected, a "library" is essentially a folder in a special location containing some source files.

You will have to restart the Arduino IDE after creating the library (creating the folder and copying the files).  Once the files are in place, you can modify them without having to restart the IDE.

Paranemertes

Ok thanks for confirming that, how do I convert this:
Code: [Select]
#ifndef FIXFFT_H
#define FIXFFT_H

#include <WProgram.h>




/*
  fix_fft() - perform forward/inverse fast Fourier transform.
  fr[n],fi[n] are real and imaginary arrays, both INPUT AND
  RESULT (in-place FFT), with 0 <= n < 2**m; set inverse to
  0 for forward transform (FFT), or 1 for iFFT.
*/
int fix_fft(char fr[], char fi[], int m, int inverse);



/*
  fix_fftr() - forward/inverse FFT on array of real numbers.
  Real FFT/iFFT using half-size complex FFT by distributing
  even/odd samples into real/imaginary arrays respectively.
  In order to save data space (i.e. to avoid two arrays, one
  for real, one for imaginary samples), we proceed in the
  following two steps: a) samples are rearranged in the real
  array so that all even samples are in places 0-(N/2-1) and
  all imaginary samples in places (N/2)-(N-1), and b) fix_fft
  is called with fr and fi pointing to index 0 and index N/2
  respectively in the original array. The above guarantees
  that fix_fft "sees" consecutive real samples as alternating
  real and imaginary samples in the complex array.
*/
int fix_fftr(char f[], int m, int inverse);




#endif





and this:
Code: [Select]
All data are fixed-point short integers, in which -32768
  to +32768 represent -1.0 to +1.0 respectively. Integer
  arithmetic is used for speed, instead of the more natural
  floating-point.

  For the forward FFT (time -> freq), fixed scaling is
  performed to prevent arithmetic overflow, and to map a 0dB
  sine/cosine wave (i.e. amplitude = 32767) to two -6dB freq
  coefficients. The return value is always 0.

  For the inverse FFT (freq -> time), fixed scaling cannot be
  done, as two 0dB coefficients would sum to a peak amplitude
  of 64K, overflowing the 32k range of the fixed-point integers.
  Thus, the fix_fft() routine performs variable scaling, and
  returns a value which is the number of bits LEFT by which
  the output must be shifted to get the actual amplitude
  (i.e. if fix_fft() returns 3, each value of fr[] and fi[]
  must be multiplied by 8 (2**3) for proper scaling.
  Clearly, this cannot be done within fixed-point short
  integers. In practice, if the result is to be used as a
  filter, the scale_shift can usually be ignored, as the
  result will be approximately correctly normalized as is.

  Written by:  Tom Roberts  11/8/89
  Made portable:  Malcolm Slaney 12/15/94 malcolm@interval.com
  Enhanced:  Dimitrios P. Bouras  14 Jun 2006 dbouras@ieee.org
  Modified for 8bit values David Keller  10.10.2010
*/


#define N_WAVE 256    /* full length of Sinewave[] */
#define LOG2_N_WAVE 8 /* log2(N_WAVE) */




/*
  Since we only use 3/4 of N_WAVE, we define only
  this many samples, in order to conserve data space.
*/



const prog_int8_t Sinewave[N_WAVE-N_WAVE/4] PROGMEM = {
0, 3, 6, 9, 12, 15, 18, 21,
24, 28, 31, 34, 37, 40, 43, 46,
48, 51, 54, 57, 60, 63, 65, 68,
71, 73, 76, 78, 81, 83, 85, 88,
90, 92, 94, 96, 98, 100, 102, 104,
106, 108, 109, 111, 112, 114, 115, 117,
118, 119, 120, 121, 122, 123, 124, 124,
125, 126, 126, 127, 127, 127, 127, 127,

127, 127, 127, 127, 127, 127, 126, 126,
125, 124, 124, 123, 122, 121, 120, 119,
118, 117, 115, 114, 112, 111, 109, 108,
106, 104, 102, 100, 98, 96, 94, 92,
90, 88, 85, 83, 81, 78, 76, 73,
71, 68, 65, 63, 60, 57, 54, 51,
48, 46, 43, 40, 37, 34, 31, 28,
24, 21, 18, 15, 12, 9, 6, 3,

0, -3, -6, -9, -12, -15, -18, -21,
-24, -28, -31, -34, -37, -40, -43, -46,
-48, -51, -54, -57, -60, -63, -65, -68,
-71, -73, -76, -78, -81, -83, -85, -88,
-90, -92, -94, -96, -98, -100, -102, -104,
-106, -108, -109, -111, -112, -114, -115, -117,
-118, -119, -120, -121, -122, -123, -124, -124,
-125, -126, -126, -127, -127, -127, -127, -127,

/*-127, -127, -127, -127, -127, -127, -126, -126,
-125, -124, -124, -123, -122, -121, -120, -119,
-118, -117, -115, -114, -112, -111, -109, -108,
-106, -104, -102, -100, -98, -96, -94, -92,
-90, -88, -85, -83, -81, -78, -76, -73,
-71, -68, -65, -63, -60, -57, -54, -51,
-48, -46, -43, -40, -37, -34, -31, -28,
-24, -21, -18, -15, -12, -9, -6, -3, */
};






/*
  FIX_MPY() - fixed-point multiplication & scaling.
  Substitute inline assembly for hardware-specific
  optimization suited to a particluar DSP processor.
  Scaling ensures that result remains 16-bit.
*/
inline char FIX_MPY(char a, char b)
{
 
  //Serial.println(a);
//Serial.println(b);
 
 
    /* shift right one less bit (i.e. 15-1) */
    int c = ((int)a * (int)b) >> 6;
    /* last bit shifted out = rounding-bit */
    b = c & 0x01;
    /* last shift + rounding bit */
    a = (c >> 1) + b;

  /*
  Serial.println(Sinewave[3]);
  Serial.println(c);
  Serial.println(a);
  while(1);*/

    return a;
}

/*
  fix_fft() - perform forward/inverse fast Fourier transform.
  fr[n],fi[n] are real and imaginary arrays, both INPUT AND
  RESULT (in-place FFT), with 0 <= n < 2**m; set inverse to
  0 for forward transform (FFT), or 1 for iFFT.
*/
int fix_fft(char fr[], char fi[], int m, int inverse)
{
    int mr, nn, i, j, l, k, istep, n, scale, shift;
    char qr, qi, tr, ti, wr, wi;

    n = 1 << m;

    /* max FFT size = N_WAVE */
    if (n > N_WAVE)
  return -1;

    mr = 0;
    nn = n - 1;
    scale = 0;

    /* decimation in time - re-order data */
    for (m=1; m<=nn; ++m) {
  l = n;
  do {
l >>= 1;
  } while (mr+l > nn);
  mr = (mr & (l-1)) + l;

  if (mr <= m)
continue;
  tr = fr[m];
  fr[m] = fr[mr];
  fr[mr] = tr;
  ti = fi[m];
  fi[m] = fi[mr];
  fi[mr] = ti;
    }

    l = 1;
    k = LOG2_N_WAVE-1;
    while (l < n) {
  if (inverse) {
/* variable scaling, depending upon data */
shift = 0;
for (i=0; i<n; ++i) {
    j = fr[i];
    if (j < 0)
  j = -j;
    m = fi[i];
    if (m < 0)
  m = -m;
    if (j > 16383 || m > 16383) {
  shift = 1;
  break;
    }
}
if (shift)
    ++scale;
  } else {
/*
  fixed scaling, for proper normalization --
  there will be log2(n) passes, so this results
  in an overall factor of 1/n, distributed to
  maximize arithmetic accuracy.
*/
shift = 1;
  }
  /*
    it may not be obvious, but the shift will be
    performed on each data point exactly once,
    during this pass.
  */
  istep = l << 1;
  for (m=0; m<l; ++m) {
j = m << k;
/* 0 <= j < N_WAVE/2 */
wr =  pgm_read_word_near(Sinewave + j+N_WAVE/4);

/*Serial.println("asdfasdf");
Serial.println(wr);
Serial.println(j+N_WAVE/4);
Serial.println(Sinewave[256]);

Serial.println("");*/


wi = -pgm_read_word_near(Sinewave + j);
if (inverse)
    wi = -wi;
if (shift) {
    wr >>= 1;
    wi >>= 1;
}
for (i=m; i<n; i+=istep) {
    j = i + l;
    tr = FIX_MPY(wr,fr[j]) - FIX_MPY(wi,fi[j]);
    ti = FIX_MPY(wr,fi[j]) + FIX_MPY(wi,fr[j]);
    qr = fr[i];
    qi = fi[i];
    if (shift) {
  qr >>= 1;
  qi >>= 1;
    }
    fr[j] = qr - tr;
    fi[j] = qi - ti;
    fr[i] = qr + tr;
    fi[i] = qi + ti;
}
  }
  --k;
  l = istep;
    }
    return scale;
}

/*
  fix_fftr() - forward/inverse FFT on array of real numbers.
  Real FFT/iFFT using half-size complex FFT by distributing
  even/odd samples into real/imaginary arrays respectively.
  In order to save data space (i.e. to avoid two arrays, one
  for real, one for imaginary samples), we proceed in the
  following two steps: a) samples are rearranged in the real
  array so that all even samples are in places 0-(N/2-1) and
  all imaginary samples in places (N/2)-(N-1), and b) fix_fft
  is called with fr and fi pointing to index 0 and index N/2
  respectively in the original array. The above guarantees
  that fix_fft "sees" consecutive real samples as alternating
  real and imaginary samples in the complex array.
*/
int fix_fftr(char f[], int m, int inverse)
{
    int i, N = 1<<(m-1), scale = 0;
    char tt, *fr=f, *fi=&f[N];

    if (inverse)
  scale = fix_fft(fi, fr, m-1, inverse);
    for (i=1; i<N; i+=2) {
  tt = f[N+i-1];
  f[N+i-1] = f[i];
  f[i] = tt;
    }
    if (! inverse)
  scale = fix_fft(fi, fr, m-1, inverse);
    return scale;
}


into .h and .cpp files?
"It's Dr. Evil. I didn't spend six years in Evil Medical School to be called 'mister,' thank you very much."

PaulS

Quote
Ok thanks for confirming that, how do I convert this:
and this:
into .h and .cpp files?

With the rename command? Those are the contents of the .h and .cpp files. Just save them with the appropriate extension.

Paranemertes

Do you mean go to> save as> then under filetype choos a .h or .cpp? I tried that and nothing popped up.... could you be more specific? Thanks though
"It's Dr. Evil. I didn't spend six years in Evil Medical School to be called 'mister,' thank you very much."

PaulS

Quote
Do you mean go to> save as> then under filetype choos a .h or .cpp? I tried that and nothing popped up.... could you be more specific?

Use a regular text editor, not the IDE. The IDE can't change the extension once it has been defined.

Paranemertes

"It's Dr. Evil. I didn't spend six years in Evil Medical School to be called 'mister,' thank you very much."

PaulS

Quote
So like word?

Word isn't a test editor. Notepad is.

Paranemertes

ok test editer not:
Quote
a regular text editor

thanks ill try that
"It's Dr. Evil. I didn't spend six years in Evil Medical School to be called 'mister,' thank you very much."

PaulS

Quote
ok test editer not:

No. Text editor. Mine was a typo.

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