Countdown timer with buzzer output and button input

Projects General Guidance
1

it wont turn the buzzer off or respond when the buzzer is on

int seconds = 20;
int buzzer = 12;
int btncount;
int btn = 2 ;

void setup() {
  // put your setup code here, to run once:
Serial.begin(9600);
pinMode(buzzer, OUTPUT);
}

void loop() {


if (digitalRead( btn ) == LOW) //check if button is pressed
{
  ++ btncount; // if pressed add one to variable btncount
  delay(200);
}
if (btncount == 1){
 
  Serial.println(seconds);
  seconds -= 1;
  delay(1000);
while (seconds <=-1 && seconds >= -10){
digitalWrite(buzzer, HIGH);
delay(2);
digitalWrite(buzzer, LOW);
delay(2);
}
}
if (digitalRead( btn ) == LOW){
++ btncount;
}
if (btncount > 1){
   btncount=0;
seconds == 20;
digitalWrite(buzzer, LOW);
Serial.println("reset");
}


}
2

It would help if you describe what the code is supposed to do.

Observations:

  1. You didn't configure btn as an input in setup(). I would suggest:

pinMode(btn, INPUT_PULLUP);

  1. You never modify seconds in this while loop. If you ever enter the loop you will stay in it forever!
    while (seconds <= -1 && seconds >= -10) {
      digitalWrite(buzzer, HIGH);
      delay(2);
      digitalWrite(buzzer, LOW);
      delay(2);
    }
  1. How is your button wired?
3

What is the intent of this line of code? '=' is assignment, '==' is comparison.

4

thanks for the quick reply the code starts at 20 seconds counts down fine, when reaches -1 the buzzer goes off. im trying to then reset it when the buzzers on

5

And:

void loop() {
  if (digitalRead( btn ) == LOW) //check if button is pressed
  {
    ++ btncount; // if pressed add one to variable btncount
    delay(200);
  }
  if (btncount == 1) {
    Serial.println(seconds);
    seconds -= 1;
    delay(1000);
    while (seconds <= -1 && seconds >= -10) {
      digitalWrite(buzzer, HIGH);
      delay(2);
      digitalWrite(buzzer, LOW);
      delay(2);
      if (digitalRead( btn ) == LOW) {
        ++ btncount;
      }
      if (btncount > 1) {
        btncount = 0;
        seconds = 20;       
        Serial.println("reset");
        break;
      }
    }
  }
}
1 Like
6

the button is wired to digital pin 2 then + and ground

7

Let me see if I have this correct:

When the Arduino starts the buzzer is on for 20 secs. When the buzzer goes off then press the buzzer to turn on the buzzer for 20 seconds again.

8

yeah or to just stop the buzzer period

9

ill run this now thnx :melting_face:

10

this is perfect thanks so much!!

11

1 last thing how would i make it pause resume mid way?

12

Here is a better way without using delays. You can turn the LED on and off at any time:

const int btn = 2;
const int buzzer = 12;
const unsigned long buzzerOnTime = 20000;

void setup(void)
{
  Serial.begin(9600);
  pinMode(buzzer, OUTPUT);
  pinMode(btn, INPUT_PULLUP);
  digitalWrite(buzzer, HIGH);
}

void loop()
{
  static unsigned long prevMillis = millis();
  static int lastBtnState = digitalRead(btn);

  int btnState = digitalRead(btn);
  long currentMillis = millis();

  if (btnState != lastBtnState)
  {
    delay(50); // debounce
    lastBtnState = btnState;

    if (btnState == LOW)
    {
      // If buzzer is on turn it off. If buzzer is off then turn it on.
      digitalWrite(buzzer, !digitalRead(buzzer));
      prevMillis = currentMillis;
    }
  }

  if (digitalRead(buzzer) == HIGH && currentMillis - prevMillis >= buzzerOnTime)
  {
    // If buzzer has  been on for 20 seconds then turn it off
    digitalWrite(buzzer, LOW);
  }
}
1 Like
13

thanks man this is great i like the logic gonna save it to my buzzer doc for the future ;D

14

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