Digital volume for square waves in Arduino Nano.

[Teleno]

This library is good for any Atmega328P board to generate square waves at controllable volumes. It replaces a mechanical sound pot by programattically setting the volume via a menu and up/down buttons, rotary encoder etc. It can even modulate the sound with attack, sustain and decay to (see examples inlcuded in the library).

This is how it works:

- Timer0 produces a PWM signal at a fixed frequency beyond the audible spectrum (62.5 KHz).
- Timer2 produces a square wave whose frequency can be set by the application.
- TImer2 gates the output of TImer0 (pass if high, clear if low).
- The volume of the square wave of TImer2 will depend on the duty cycle of Timer0 (set by the application).

The sound is output to the OC0B pin (D5). Add a simple RC filter and you're set.

Example code to generate a frequency with a given volume:

#include "VolumeSquareWaveNano.h"

VolumeSquareWaveNano v;

void setup() {
  // put your setup code here, to run once:
  v.init();
}

void loop() {
  // Just a frequency at 50% volume
  v.setFrequency(2000);
  v.setVolumePercent(50);
  while(1);
}​

To install the library, go to your sketches folder and create a "library" subfolder (if not yet there). Extract the "VolumeSquareWaveNano" folder to said subfolder. Inside there's an "examples" subfolder with three simple demo sketches.

VolumeSquareWaveNano.zip

Heartbeat:

Simple bell-like modulation of two tones:

[Teleno]

This is an improved version of the library.

VolumeSymetric.zip

The PWM modulation is now symmetric. For example, if the duty cycle during the "on" time of the square wave (yellow trace) is 75% then the duty cycle during the "off" time is 25%. The resulting low-pass sound wave (blue trace) is centrered around Vcc/2 and is perfectly symmetric.



The modulation signal (unfiltered Timer0 output, blue) looks like this



The sound produced is free from cracking artifacts because the DC bias is fixed to Vcc/2, unlike the former library.

This is an example of the sound caused when sweeping in and out of a target by modulating both the frequency and amplitude as a function of the target signal. Base frequency is 216 Hz. See the sketch "target.ino" in the examples folder.

And this is how it would sound with amplitude only modulation.

[pito]

fatal error: VolumeSquareWaveNano.h: No such file or directory

[Teleno]

fatal error: VolumeSquareWaveNano.h: No such file or directory

How did you do the installation?

The unzipped files should look as follows:

(Your sketches folder) - "Documents\Arduino" in my case
 |
 |_VolumeSymmetric
    |
    |_ _VolumeSymmetric.cpp
    |_ _VolumeSymmetric.h
    |_ _examples
          |_ _demo1
          |     |_ __demo1.ino
          |_ _demo2
          |       |__demo2.ino
          |_ _halloween
          |       |__halloween.ino
          |_ _nutcracker
          |       |__ nutcracker.ino​
          |_ _target
          |       |__target.ino
          |_ _twinkle
                  |__twinkle.ino​​​​ 

Latest version

https://www.geotech1.com/forums/file...etch?id=419973

[pito]

I didn't, I do not see a zip file for it .

[Teleno]

I didn't, I do not see a zip file for it .

Try this link

https://www.geotech1.com/forums/file...etch?id=419973

Pin D5 is the Timer0 output (speaker)
Pin D3 is the raw frequency of TImer2 for testing (trigering the scope, for example)

[pito]

zip library - know how to add a zip library to arduino but not separate cpp. and h. files which are in your folder.

[Teleno]

zip library - know how to add a zip library to arduino but not separate cpp. and h. files which are in your folder.

I don't understand what the problem is.

Just unzip and then in Arduino IDE open one of the examples, "demo1.ino" is the simplest, and look how they're coded.

#include "VolumeSymmetric.h"

VolumeSymmetric v;

void setup() {
  // put your setup code here, to run once:
  v.init();
}

void loop() {
  // Just a frequency at 50% volume
  v.setFrequency(2000);
  v.setVolumePercent(90);
  while(1);
}
​ 

[Qiaozhi]

The problem is that the .h and .cpp files both need to be in the same directory as the sketch.
Simply copy the two files into the demo1 folder (for example) and the sketch will compile.

[pito]

Just unzip and then in Arduino IDE open one of the examples, "demo1.ino" = I did

[Teleno]

The problem is that the .h and .cpp files both need to be in the same directory as the sketch.
Simply copy the two files into the demo1 folder (for example) and the sketch will compile.

Strange, in my Arduino IDE (2.2.1) that requirement is not necessary.

I think I should have put those files under a "src" folder.

Try this: in the VolumeSymmetric folder create an "src" subfolder and move the .ccp and .h there.

This zip has the correct directory tree

VolumeSymmetric.zip

https://www.geotech1.com/forums/filedata/fetch?id=419984&d=1707346796

[pito]

need to be in the same directory as the sketch. = ok, done

This sketch is using i ++, how to change to arduino analog pin ?

[Teleno]

need to be in the same directory as the sketch. = ok, done

This sketch is using i ++, how to change to arduino analog pin ?

You can't change the pin. It's fixed and it's D5.

[pito]

D5 = output, input pin ?

[Teleno]

D5 = output, input pin ?

D5 is PWM output for the speaker. You don't need to configure it, it's already done in the code and can'r be changed.