Hello friends,
in this message I posted an extension to generate tones:
Now we are going to build a tone generator using JavaScript and measure its frequency with Arduino.
If you want you can take a look at my tutorial in Spanish:
http://kio4.com/arduino/6B_Frecuencimetro.htm
We'll start with Arduino...
1.- Frequency meter with Arduino.
We will use the PulseIn function
Here an example:
https://www.circuitstoday.com/frequency-counter-using-arduino.
Our code, the signal to be measured enters through terminal 12:
int input=12;
int high_time;
int low_time;
float time_period;
float frequency;
void setup()
{
Serial.begin(9600);
pinMode(input,INPUT);
}
void loop(){
high_time=pulseIn(input,HIGH);
low_time=pulseIn(input,LOW);
time_period=high_time+low_time;
time_period=time_period/1000;
frequency=1000/time_period;
Serial.println(frequency);
delay(1000);
}
2.- Connections. Amplifier.
The sound signal that comes out through the headphone jack of mobile phones usually has a maximum voltage of about 200 mV.
Arduino works with 5V digital inputs, so we need an amplifier to turn the voltage up from 200mV to 5V.
The amplifier can work in cut/saturation, it does not need to be linear amplification
We will use this amplifier module: module LM386
3.- Tone generator with JavaScript.
I adapted this code from this website:
sonido2.html
<!DOCTYPE html>
<html>
<head><meta charset="utf-8"></head><body>
<body>
<!-- <button onclick='beep();'>Play</button> -->
<script>
datos = window.AppInventor.getWebViewString(); // Entrada de datos.
datos = datos + ":";
valores = datos.split(":");
frequency = valores[0];
type = valores[1];
volume = valores[2];
duration = valores[3];
audioCtx = new(window.AudioContext || window.webkitAudioContext)();
function beep() {
var oscillator = audioCtx.createOscillator();
var gainNode = audioCtx.createGain();
oscillator.connect(gainNode);
gainNode.connect(audioCtx.destination);
gainNode.gain.value = volume;
oscillator.frequency.value = frequency;
oscillator.type = type;
oscillator.start();
setTimeout(
function() {
oscillator.stop();
},
duration
);
};
beep()
</script>
</body>
4.- App Inventor code.
p67B_JavaScript_generadortonoi.aia (8.3 KB)
- Serial Monitor.
We introduce a 1000 Hz signal, observe the error.
5.- Other code.
<!DOCTYPE html>
<html>
<head><meta charset="utf-8"></head><body>
<body>
<button onclick='play();'>Play</button>
<script>
var frequency = 1000;
var data = {
1: {duration:500, sleep:1000},
0: {duration:500, sleep:500}
}
var audio = new(window.AudioContext || window.webkitAudioContext)();
//function creates an Oscillator. In this code we are creating an Oscillator for every tune, which help you control the gain.
//If you want, you can try creating the Oscillator once and stopping/starting it as you wish.
function createOscillator(freq, duration) {
var attack = 10, //duration it will take to increase volume full sound volume, makes it more natural
gain = audio.createGain(),
osc = audio.createOscillator();
gain.connect(audio.destination);
// gain.gain.setValueAtTime(0, audio.currentTime); //change to "1" if you're not fadding in/out
// gain.gain.linearRampToValueAtTime(1, audio.currentTime + attack / 1000); //remove if you don't want to fade in
// gain.gain.linearRampToValueAtTime(0, audio.currentTime + duration / 1000); //remove if you don't want to fade out
gain.gain.value = 4;
osc.frequency.value = freq;
osc.type = "sine";
osc.connect(gain);
osc.start(0);
setTimeout(function() {
osc.stop(0);
osc.disconnect(gain);
gain.disconnect(audio.destination);
}, duration)
}
function play() {
//your pattern
var song = [1,0,0,0,0];
timeForNext = 0;
for (i=0;i<song.length;i++){
duration = data[song[i]].duration;
//use timeout to delay next tune sound
window.setTimeout(function(){
createOscillator(frequency, duration);
},timeForNext);
timeForNext+=data[song[i]].sleep;
}
}
//play the music
play();
</script>
</body>
With the arrival of the runJavascript block for the Webviewer, it is now possible to play a tone/tones with an empty, hidden webviewer:
var frequency = 440;
var type = 'sine';
var volume = 0.5;
var duration = 1000;
var audioCtx = new AudioContext();
var oscillator = audioCtx.createOscillator();
var gainNode = audioCtx.createGain();
oscillator.connect(gainNode);
gainNode.connect(audioCtx.destination);
gainNode.gain.value = volume;
oscillator.frequency.value = frequency;
oscillator.type = type;
oscillator.start();
setTimeout( function() {
oscillator.stop();
},
duration );
(added to FAQ)