AVR to ESP32 Timer

Projects Programming
1

Hello everyone,

I am struggling with an issue here. I was using Arduino but now i have to transfer my code to ESP32 WRover B. Below i have part of my code. The timer suppose to count and interrupt function should work. How can i transfer it to ESP32? Are there anything like OCR2B or OCR1A in ESP32? Thank you for helping.

void startPlayback()
{
  pinMode(SPEAKER, OUTPUT);
  audioRunning = true;
  

  // Set up Timer 2 to do pulse width modulation on the speaker pin.
  ASSR &= ~(_BV(EXCLK) | _BV(AS2));                         // Use internal clock (datasheet p.160)

  TCCR2A |= _BV(WGM21) | _BV(WGM20);                        // Set fast PWM mode  (p.157)
  TCCR2B &= ~_BV(WGM22);

  TCCR2A = (TCCR2A | _BV(COM2B1)) & ~_BV(COM2B0);           // Do non-inverting PWM on pin OC2B (p.155)
  TCCR2A &= ~(_BV(COM2A1) | _BV(COM2A0));                   // On the Arduino this is pin 3.
  TCCR2B = (TCCR2B & ~(_BV(CS12) | _BV(CS11))) | _BV(CS10); // No prescaler (p.158)

  OCR2B = pgm_read_byte(&idle_data[0]);                     // Set initial pulse width to the first sample.
  OCR2B = pgm_read_byte(&idle_data2[0]);  

  // Set up Timer 1 to send a sample every interrupt.
  cli();

  TCCR1B = (TCCR1B & ~_BV(WGM13)) | _BV(WGM12);             // Set CTC mode (Clear Timer on Compare Match) (p.133)
  TCCR1A = TCCR1A & ~(_BV(WGM11) | _BV(WGM10));             // Have to set OCR1A *after*, otherwise it gets reset to 0!

  TCCR1B = (TCCR1B & ~(_BV(CS12) | _BV(CS11))) | _BV(CS10); // No prescaler (p.134)

  OCR1A = F_CPU / BASE_RATE;                                // Set the compare register (OCR1A).
                                                            // OCR1A is a 16-bit register, so we have to do this with
                                                            // interrupts disabled to be safe.

  TIMSK1 |= _BV(OCIE1A);                                   // Enable interrupt when TCNT1 == OCR1A (p.136)

  //lastSample = pgm_read_byte(&idle_data2[idle_len2-1]);
  curEngineSample = 0;

  sei();
  


}



ISR(TIMER1_COMPA_vect) {
  OCR1A = currentSmpleRate;


  if (curEngineSample >= idle_len ) { // Loop the sample

      curEngineSample = 0; 
         
  }


  if ((curEngineSample) % 2 == 0) { 

      //analogWrite(SPEAKER,vol);

      //OCR2B = pgm_read_byte(&idle_data[j]);
      ++j;

      if (j >= idle_len ) {

      j = 0; 

      }
 
  }

   if ((curEngineSample) % 2 != 0) { 

      //analogWrite(SPEAKER,vol2);
      

      OCR2B = pgm_read_byte(&idle_data2[i]);
       ++i;

       if (i >= idle_len ) {

      i = 0; 

       }

        
  }   

      
      ++curEngineSample;

      
      
}
2

Hi tkaracali,

i'm not an expert about AVR-timers nor for ESP32-timers.
Your sourcefile has a part

void startPlayback()
{
  pinMode(SPEAKER, OUTPUT);
  audioRunning = true;

There is a reason why questions should include not the shortest question possible but quite a lot backround information. From this small codesnippet I have no idea which library you are using.
Now I have to ask for these things:

So I guess your project wants to playback audio from somewhere.
For the arduino-IDE there are so many ready to use libraries that there is a good chance to find a library that does the same thing and is usable with ESP32-cores. On such a low-level like hardware-timers there are a lot of differencies between different microcontrollers. For sure it is not done with exchangeing some names.

Have you ever looked up the library-manager if keyword "ESP32" if there is an equalent ESP32-library?

Inside the arduino-IDE in the main-menu click on "tools" and choose "library-manager"

Another approach: if you write about the whole project that uses this StartPlayback-function maybe another and easier to achieve solution can be suggested.

best regards

Stefan

3

Hello Stefan,

Thank you for your answer.

The main thing i want to do is playing two wav files (which are converted into hex) together or overlap with %50 maybe.

Other part of it is while playing two wav files repeatedly, i want to change the pitch of them with potentiometre.( I can do it now)

Lastly, while pitch is rising i want one wav file volume to decrease and other one increase according to pitch value. Like when one song fading out while other fading in.

This is a summary of my project. I can do most of the stuff at arduino but now i want to do it in ESP32.

Best Regards
Tunç

4

Are there anything like OCR2B or OCR1A in ESP32?

Yes, but they function differently and have different names. The code that uses them would have to be completely re-written to work on ESP32.