Some Mozzi audio experiments

Using my own samples with Mozzi

Have finally cracked getting my own samples into Mozzi. The sound clips need to be VERY short (around 0.5 seconds) or they are too big for the Nano. I also tried mono to see if that saved space, but then there was no sound at all. I really raised the volume of this sample and the clipping isn’t too noticeable compared to the previously-encoded version , as it clips because of the processing anyway.

Here’s the code:

/*  Example of playing a sampled sound,
    using Mozzi sonification library.
    Demonstrates one-shot samples scheduled
    with EventDelay.
    Circuit: Audio output on digital pin 9 on a Uno or similar, or
    DAC/A14 on Teensy 3.1, or 
    check the README or
    Mozzi help/discussion/announcements:!forum/mozzi-users
    Tim Barrass 2012, CC by-nc-sa.

#include <MozziGuts.h>
#include <Sample.h> // Sample template
#include <samples/alienwave.h>
#include <EventDelay.h>

#define CONTROL_RATE 64

// use: Sample <table_size, update_rate> SampleName (wavetable)
Sample <alienwave_NUM_CELLS, AUDIO_RATE> aSample(alienwave_DATA);

// for scheduling sample start
EventDelay kTriggerDelay;

void setup(){
  aSample.setFreq((float) alienwave_SAMPLERATE / (float) alienwave_NUM_CELLS); // play at the speed it was recorded
  kTriggerDelay.set(1500); // 1500 msec countdown, within resolution of CONTROL_RATE

void updateControl(){

int updateAudio(){
  return (int);

void loop(){

With thanks to Tim Barass and his very helpful forum for help getting this working.

Arduino – Mozzi Piezo input tests

“A piezo creates a varying voltage when you squeeze it. [We’ll] use it as a sensor by measuring the voltage the piezo produces across a 1 megaOhm resistor…Notice it has a very fast response, especially a sharp attack and decay when it’s knocked.”

This first test was changing the frequency as the piezo was scraped and touched.

And the audio version:


Piezo sample trigger (& speed)


Piezo sample scrub

And finally an example of an external speaker circuit. Will need to work on the output level for this.

Arduino audio – further Mozzi tests

A video showing an Arduino Nano running the Mozzi library, which allows sounds generated from sensors. This uses the LDR + resistor as input to Analog Pins A1 +  A2, and using the code from Arduino➞File➞Examples➞Mozzi➞03.Sensors➞Knob_LightLevel_x2_FMsynth

And here’s the attendant audio.

Arduino audio tests

Arduino audio tests using the Mozzi library, a Nano board, a light dependent resistor and a potentiometer (volume control).