Once class instance affecting another(?)

[fluxia]

HI All

I am a bit puzzled by the result of my sketch. I am building a class to create sine waves so that I can create different waves and then use them to modulate each other. I got stuckl early in the process though as I am observing a behaviour that I did not expect. If I create one sine wave it works as expected, but if in my sketch I create a second wave, it seems to affect the first one . Look at this simple sketch:

#include "Sinewave.h"

SineWave mainWave(100, 0.05);
SineWave modulatingWave(50, 0.5);

void setup() {
    Serial.begin(115200);
}

void loop() {

  float main =  mainWave.getSineValue(); 
  float modulator = modulatingWave.getSineValue(); 
  Serial.print("main wave: ");
  Serial.println(main);
  // Serial.print("modulator: ");
  // Serial.println(modulator);
}

if I comment out this line:float modulator = modulatingWave.getSineValue();

the putput of this sketch is:

however, if I leave that line in the sketch, the outcome becomes:

even though I am only priting out the first wave (the second one (modulator) is not being printed out).

these are my class files:

#ifndef SINEWAVE_H
#define SINEWAVE_H

#include<Arduino.h>



class SineWave {
  private:
    int _amplitude = 100;               // Amplitude of the sine wave max 255, but offset needs to follow
    float _frequency = 0.001;           // Frequency of the sine wave - try value bewteewn 0.5 and 0.001
    int _offset = 127;                  // Offset to ensure the sine wave is always positive
    float _angle = 0;                   // Angle in radians
    const uint8_t _updateInterval = 20; // Update interval in milliseconds
    unsigned long _previousMillis = 0;  // Stores the last time the sine value was updated
   

  public:
    SineWave(){}
    SineWave(int amplitude);
    SineWave(int amplitude,float frequency);
    SineWave(int amplitude,float frequency, int offset);
    float getSineValue();
    void setAmplitude(int amplitude);
    void setFrequency(float frequency);
    void setOffset(int offset);
};


#endif

#include "Sinewave.h"

SineWave::SineWave(int amplitude){
  _amplitude = amplitude;
}
SineWave::SineWave(int amplitude,float frequency){
  _amplitude = amplitude;
  _frequency = frequency;
}
SineWave::SineWave(int amplitude,float frequency, int offset){
  _amplitude = amplitude;
  _frequency = frequency;
  _offset = offset;
}


float SineWave::getSineValue(){
      unsigned long currentMillis = millis();                     
      if (currentMillis - _previousMillis >= _updateInterval) {   
        _previousMillis = currentMillis;
        float sineValue = _amplitude * sin(_angle) + _offset;     
        _angle += _frequency;                                     
        if (_angle >= TWO_PI) {                                   
          _angle -= TWO_PI;
        }
        return sineValue;
      } 
    }
void SineWave::setAmplitude(int amplitude){
  _amplitude = amplitude;
}
void SineWave::setFrequency(float frequency){
  _frequency = frequency;
}
void SineWave::setOffset(int offset){
  _offset = offset;  
}

[Juraj]

getSineValue is missing a return value if the condition is false

[fluxia]

I dint' think I needed to add a return value in that case, as I don't want the function to do anything if the condition is false. However, I tried to change it as you said:

float SineWave::getSineValue(){
  float sineValue;
  unsigned long currentMillis = millis();                     // Check if it's time to update the sine wave value
  if (currentMillis - _previousMillis >= _updateInterval) {   // Save the last time you updated the sine value
    _previousMillis = currentMillis;
    sineValue = _amplitude * sin(_angle) + _offset;     // Calculate the sine wave value
    _angle += _frequency;                                     // Increment the angle
    if (_angle >= TWO_PI) {                                   // Wrap the angle to stay within 0 to 2*PI range
      _angle -= TWO_PI;
    }
    return sineValue;
  }
  else {
    return;
  } 
}

unfortunately the result has not changed. My question is why does it work perfectly until another object calls the same function...?

[fluxia]

I see... so I presume the solution will be to make sineValue a private member variable... I am gonna try...

[fluxia]

@Delta_G @Juraj
It works !!
thank you !