I need to make a 6 hour countdown. I need help

Using Arduino Project Guidance
1

The void function keeps repeating and it shows the temperature and the timer every millisecond so I can't see anything, I also need help making it so after it ends it makes a buzzer sound and if the temperature is 28° it starts the countdown again. The countdown also shouldn't be affected by changes in temperature in the 6 hour time span. Also I need to make a button to start the countdown, I need help urgently.

image
image1111×721 113 KB

#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x20,16,2);

float tempValue;
float voltage;
float tempC;
float tempF;
int buzzer = 8;

int hours = 6;
int minutes = 0;
int seconds = 0;
  
void setup(){
  lcd.init();
  lcd.backlight();
  pinMode(buzzer, OUTPUT);

  lcd.setCursor(3,0);
  lcd.print("TECH FAIR");
  lcd.setCursor(5,1);
  lcd.print("NOMBRE");
  delay(2000);
  lcd.clear();
  
}

void loop(){
  
  tempValue = analogRead(A0);
  voltage = (tempValue * 5) / 1024;
  tempC = (voltage-0.5)* 100;
  tempF = (tempC * 1.8) + 32;
  
  timer();
} 

void timer(){
  if(tempC >= 28){
      lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Countdown:");

  // formato HH:MM:SS
    lcd.setCursor(0, 1);
    lcd.print(hours);
    lcd.print(":");
    if (minutes < 10) {
      lcd.print("0"); // zero para los digitos de 1
  }
    lcd.print(minutes);
    lcd.print(":");
    if (seconds < 10) {
      lcd.print("0");
  }
    lcd.print(seconds);

  // quitale al countdown
    if (seconds > 0) {
      seconds--;
    } else {
      if (minutes > 0) {
        minutes--;
        seconds = 59;
      } else {
        if (hours > 0) {
          hours--;
          minutes = 59;
          seconds = 59;
      }
    }
  }
    
  }else{
    lcd.clear();
    lcd.setCursor(0,1);
    lcd.print("Temp (C):");
    lcd.setCursor(8,0);
    lcd.print(tempC);
    }
}
2

Hi @juliojeda ,

Welcome to the forum..

curious, is the temp producing correct values??

give this a try..

#include <LiquidCrystal_I2C.h>

#define BTN_PIN 7

LiquidCrystal_I2C lcd(0x20, 16, 2);

float tempValue;
float voltage;
float tempC;
float tempF;
int buzzer = 8;

int hours = 6;
int minutes = 0;
int seconds = 0;

bool countStarted = false;
bool countFin = false;

unsigned long lastCount = 0;
unsigned long intervalCount = 1000;

unsigned long lastBuzz = 0;
int intervalBuzz = 1000;
byte buzzState = 0;
bool buzzFin = false;

unsigned long lastDebounce = 0;
int intervalDebounce = 50;
byte lastBtn = 1;


void setup() {
  Serial.begin(115200);
  lcd.init();
  lcd.backlight();
  pinMode(buzzer, OUTPUT);
  pinMode(BTN_PIN, INPUT_PULLUP);

  lcd.setCursor(3, 0);
  lcd.print("TECH FAIR");
  lcd.setCursor(5, 1);
  lcd.print("NOMBRE");
  delay(2000);
  lcd.clear();

}

void loop() {

  unsigned long now = millis();

  if (millis() - lastDebounce >= intervalDebounce) {
    byte state = digitalRead(BTN_PIN);
    if (state != lastBtn) {
      lastBtn = state;
      lastDebounce = millis();
      if (state == HIGH) {
        //button pressed and released
        if (!countStarted) {
          StartCount();
        }
      }
    }
  }


  tempValue = analogRead(A0);
  voltage = (tempValue * 5) / 1024;
  tempC = (voltage - 0.5) * 100;
  tempF = (tempC * 1.8) + 32;


  if (tempC >= 28 && !countStarted) {
    Serial.print("TempC:");
    Serial.print(tempC);
    StartCount();
  }

  if (countStarted && !countFin) {
    if (now - lastCount >= intervalCount) {
      lastCount = now;
      countFin = timer();
    }
  } else if (countStarted && countFin) {
    if (!buzzFin) {
      buzz();
    } else {
      //finsihed the buzzing..
      //reset everythings..
      buzzFin = false;
      countFin = false;
      countStarted = false;
      lcd.clear();
    }

  }
}

//starts the count down
void StartCount() {
  countStarted = true;
  lastCount = millis() - 1001;
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Countdown:");
  hours = 6;
  minutes = 0;
  seconds = 0;
  intervalBuzz = 1000;
  buzzState = 0;
}

bool timer() {
  bool result = false;
  // formato HH:MM:SS
  lcd.setCursor(0, 1);
  lcd.print(hours);
  lcd.print(":");
  if (minutes < 10) {
    lcd.print("0"); // zero para los digitos de 1
  }
  lcd.print(minutes);
  lcd.print(":");
  if (seconds < 10) {
    lcd.print("0");
  }
  lcd.print(seconds);
  int left = hours + minutes + seconds;
  if (left == 0) {
    //all done
    result = true;
  }

  // quitale al countdown
  if (seconds > 0) {
    seconds--;
  } else {
    if (minutes > 0) {
      minutes--;
      seconds = 59;
    } else {
      if (hours > 0) {
        hours--;
        minutes = 59;
        seconds = 59;
      }
    }
  }

  return result;
}

void buzz() {

  switch (buzzState) {
    case 0:  tone(buzzer, 392); lastBuzz = millis(); buzzState++; break;
    case 1: if (millis() - lastBuzz >= intervalBuzz) {
        buzzState++;
        noTone(buzzer);
        intervalBuzz = 500;
        lastBuzz = millis();
      }
      break;
    case 2: if (millis() - lastBuzz >= intervalBuzz) {
        buzzState++;
        intervalBuzz = 1000;
        tone(buzzer, 175);
        lastBuzz = millis();
      }
      break;
    case 3: if (millis() - lastBuzz >= intervalBuzz) {
        buzzState = 0;
        noTone(buzzer);
        buzzFin = true;
      }
      break;
  }
}

i did not test the full 6 hour count down obviously, had mine set to 10 seconds, seems to work properly..

have fun.. ~q

1 Like
3

Holy crap dude thanks! I think the temp is producing correct values. I tried the code and it's awesome but the timer is kinda slowed- any clue why?

If you can see in the image attached, the runtime vs the actual countdown is different- maybe its my laptop but idk

image
image1034×743 80.3 KB

thanks so much

PD: It would be great if you wanted to explain some of the stuff you did, I'd like to understand better but ofc you don't have to (my dc is tacostaco)

4

You're welcome..

The count is controlled by intervalCount which is currently set too 1000 milli seconds or 1 second, should be pretty dead on but you can adjust the interval if needed..

added a button and a millis timer to debounce..
button is input pull up, so just need to hit ground..

I changed the timer function to return whether it has finished, returns true when done..

The buzz routine demonstrates the use of a state machine, when the buzzing is finished then it sets a flag..

a few flags were added for count started, count finished and buzz finished..

You can add more state to the buzz routine if you want to play a tune or something..

this design does rely on a fast loop, so don't add any delay() functions or you can compromise the countdown interval..

I was adjusting seconds to 10, hours and minutes at 0 in the start count function for testing, looks like it was counting proper..

got it in a sim here..

I did have to change the temp calc as it was reporting like 200c, that's why I asked, could just be something in the sim, only had one temp sensor to use in there..
WoKWi pretty nice..

have fun.. ~q

1 Like
5

Actually looking at your pic, looks proper..
That's the total simulator time..
in setup there is a 2 second delay and then might be a second or so before it starts..
So yeah, looks about right.. :slight_smile:

~q

6

Yeah mine is definitely slower but that might just be on my end, I'll try it on another laptop tomorrow- thanks again!