| Mozzi version v1.1.0 sound synthesis library for Arduino |

10.Audio_Filters/LowPassFilter/LowPassFilter.ino

This example demonstrates the LowPassFilter class.

/* Example of filtering a wave,
using Mozzi sonification library.
Demonstrates LowPassFilter().
Circuit: Audio output on digital pin 9 on a Uno or similar, or
DAC/A14 on Teensy 3.1, or
check the README or http://sensorium.github.io/Mozzi/
Mozzi documentation/API
https://sensorium.github.io/Mozzi/doc/html/index.html
Mozzi help/discussion/announcements:
https://groups.google.com/forum/#!forum/mozzi-users
Tim Barrass 2012, CC by-nc-sa.
*/
#include <MozziGuts.h>
#include <Oscil.h>
#include <tables/chum9_int8.h> // recorded audio wavetable
#include <tables/cos2048_int8.h> // for filter modulation
#include <LowPassFilter.h>
#include <mozzi_rand.h>
Oscil<CHUM9_NUM_CELLS, AUDIO_RATE> aCrunchySound(CHUM9_DATA);
Oscil<COS2048_NUM_CELLS, CONTROL_RATE> kFilterMod(COS2048_DATA);
LowPassFilter lpf;
uint8_t resonance = 200; // range 0-255, 255 is most resonant
void setup(){
startMozzi();
aCrunchySound.setFreq(2.f);
kFilterMod.setFreq(1.3f);
}
void loop(){
audioHook();
}
void updateControl(){
if (rand(CONTROL_RATE/2) == 0){ // about once every half second
kFilterMod.setFreq((float)rand(255)/64); // choose a new modulation frequency
}
// map the modulation into the filter range (0-255), corresponds with 0-8191Hz
byte cutoff_freq = 100 + kFilterMod.next()/2;
lpf.setCutoffFreqAndResonance(cutoff_freq, resonance);
}
AudioOutput_t updateAudio(){
char asig = lpf.next(aCrunchySound.next());
return MonoOutput::from8Bit(asig);
}