tone was not declared in this scope

[Master811129]

Hardware:

Board: ESP32 Dev Module
Core Installation/update date: 11/jul/2017
IDE name: Arduino IDE
Flash Frequency: 80Mhz
Upload Speed: 115200

Description:

when i use tone function the arduino console says:
"tone was not declared in this scope."
if the esp32 core doesn't have tone function please add it.
thanks.

Sketch:

#include <Arduino.h>

void setup()
{
 pinMode(25,OUTPUT);
}

void loop() 
{
  tone(25,200);
  delay(1000);
  tone(25,800);
  delay(1000);
}

[lbernstone]

I think tone is part of the ledc functions in esp32. I don't have a speaker around to test, but try this:

void setup() {
  ledcSetup(0,1E5,12);
  ledcAttachPin(25,0);
}
void loop() {
  ledcWriteTone(0,800);
  delay(1000);
  uint8_t octave = 1;
  ledcWriteNote(0,NOTE_C,octave);  
  delay(1000);
}

[Master811129]

yeah it works! thank you
but why the esp32 developers didn't color the ledc codes for easier reading and coding?...
and one more question:
how i can use noTone() in ESP32?

[lbernstone]

ledcWrite(channel,0) will set the duty cycle to 0 (i.e., off).
There is a problem that prevents the esp32 from getting tone and analogWrite working in a safe fashion. Once a solution is made, tone will work just like it does on other arduinos.

[lbernstone]

If this is working for you, please close the issue.

[Master811129]

thanks again!

[KTibow]

Just in case anybody finds this, you can make a quick swap like this:

void tone(byte pin, int freq) {
  ledcSetup(0, 2000, 8); // setup beeper
  ledcAttachPin(pin, 0); // attach beeper
  ledcWriteTone(0, freq); // play tone
}

Don't know how to make it so it asynchronously stops playing after an amount of time, though. To stop it, you can do that again with 0 as the frequency, or do something like:

int playing = 0;
void tone(byte pin, int freq) {
  ledcSetup(0, 2000, 8); // setup beeper
  ledcAttachPin(pin, 0); // attach beeper
  ledcWriteTone(0, freq); // play tone
  playing = pin; // store pin
}
void noTone() {
  tone(playing, 0);
}

[lbernstone]

or my library. https://github.com/lbernstone/Tone

[connornishijima]

Why was this closed? A tone() abstraction still doesn't seem to exist in this core.

[Thomascountz]

Although this functionality is unavailable in Espressif's arduino-esp32 library, members of the community have found various work-arounds such as using the native LED Control functions to generate PWM signals.

However, looking more closely at arduino-esp32 library, not only has Espressif provided a clean API for generating tones, they've provided an interface for generating specific PWM frequencies for specific notes on the chromatic scale in different octaves.

https://github.com/espressif/arduino-esp32/blob/master/cores/esp32/esp32-hal-ledc.c#L255-L266

double ledcWriteNote(uint8_t chan, note_t note, uint8_t octave){
  const uint16_t noteFrequencyBase[12] = {
  //   C        C#       D        Eb       E        F       F#        G       G#        A       Bb        B
      4186,    4435,    4699,    4978,    5274,    5588,    5920,    6272,    6645,    7040,    7459,    7902
  };

  if(octave > 8 || note >= NOTE_MAX){
      return 0;
  }
  double noteFreq =  (double)noteFrequencyBase[note] / (double)(1 << (8-octave));
  return ledcWriteTone(chan, noteFreq);
}

Although not directly compatible with Arduino's tone(), the function allows for a clearer interface by providing named frequencies out of the box via the note_t type.

typedef enum {
    NOTE_C, NOTE_Cs, NOTE_D, NOTE_Eb, NOTE_E, NOTE_F, NOTE_Fs, NOTE_G, NOTE_Gs, NOTE_A, NOTE_Bb, NOTE_B, NOTE_MAX
} note_t;

Example Usage

Here is an example of generating PWM frequencies at 50% duty cycle to play the C-major scale.

void playScale(uint8_t pin, uint8_t channel) {
  ledcAttachPin(pin, channel);
  ledcWriteNote(pin, NOTE_C, 4);
  delay(500);
  ledcWriteNote(pin, NOTE_D, 4);
  delay(500);
  ledcWriteNote(pin, NOTE_E, 4);
  delay(500);
  ledcWriteNote(pin, NOTE_F, 4);
  delay(500);
  ledcWriteNote(pin, NOTE_G, 4);
  delay(500);
  ledcWriteNote(pin, NOTE_A, 4);
  delay(500);
  ledcWriteNote(pin, NOTE_B, 4);
  delay(500);
  ledcDetachPin(pin)
}

[jonfroehlich]

Thanks for this uncovering this functionality @Thomascountz! We incorporated it into one of our teaching lessons for our Physical Computing course: https://makeabilitylab.github.io/physcomp/esp32/tone.html. Hope it's useful to others!

[lbernstone]

Tone is now available from in the ESP32Servo library (which can be found in Arduino library manager).

[jonfroehlich]

Oh, this is great. Thanks!

[limingjie]

Verified working code and schematic.

@Thomascountz I was following your comment and it took me quite some time to realize the ledcWriteNote should write to the channel. I should have read the function declaration first.

void playScale(uint8_t pin, uint8_t channel)
{
    ledcAttachPin(pin, channel);
    ledcWriteNote(channel, NOTE_C, 4);
    delay(100);
    ledcWriteNote(channel, NOTE_D, 4);
    delay(100);
    ledcWriteNote(channel, NOTE_E, 4);
    delay(100);
    ledcWriteNote(channel, NOTE_F, 4);
    delay(100);
    ledcWriteNote(channel, NOTE_G, 4);
    delay(100);
    ledcWriteNote(channel, NOTE_A, 4);
    delay(100);
    ledcWriteNote(channel, NOTE_B, 4);
    delay(100);
    ledcDetachPin(pin);
}

Schematic

PCB