Replacing delay with millis using tone function

Projects Programming
1

Created a siren for a robot car using this code:

#define speakerPin 9

void setup() {
  }

void loop() {
  for (int hz = 440; hz < 1000; hz += 25) {
    tone(speakerPin, hz, 50);
    delay(5);
  }

  for (int hz = 1000; hz > 440; hz -= 25) {
    tone(speakerPin, hz, 50);
  }

}

In an effort to replace the delay function with millis, I tried to apply the Blink Without Delay example. While it compiles & uploads, I'm not getting the same sound effect.

#define speakerPin 9

int durationState = LOW;
int delayState = LOW;
unsigned long previousMillis = 0;
const long duration = 50;
const long noteDelay = 5;

void setup() {
}

void loop() {

  unsigned long currentMillis = millis();
  if (currentMillis - previousMillis >= duration) {
    previousMillis = currentMillis;
    if (durationState == LOW) {
      durationState = HIGH;
    }
    else {
      durationState = LOW;
    }


    for (int hz = 440; hz < 1000; hz += 25) {
      tone(speakerPin, hz, durationState);

      unsigned long currentMillis = millis();
      if (currentMillis - previousMillis >= noteDelay) {
        previousMillis = currentMillis;
        if (delayState == LOW) {
          delayState = HIGH;
        }
        else {
          delayState = LOW;
        }
      }
      digitalWrite(speakerPin, delayState);
    }

    for (int hz = 1000; hz > 440; hz -= 25) {
      tone(speakerPin, hz, durationState);
    }

  }
}
2

Welcome

Here is an example : t951856.ino - Wokwi Arduino and ESP32 Simulator

4

Thanks for the reply & the example, much appreciated. Kind of curious to know what the problem is in my coding though.

5

But you didn't do it right. The current millis is set each time round the loop and so it never gets past zero.

It is just a blocking piece of code like delay. What were you hoping it would do?

6

Yeah, it's completely wrong...

I modified the example so it does the same thing as in your first code :slight_smile: : t951856_2.ino - Wokwi Arduino and ESP32 Simulator

7

Yes, I got that I didn't do it right. :smiley:
I was hoping it would replace the delay functions in the original code and that it would produce the same effects as the original code.

8

Thankyou, that was very helpful. Much appreciated.