Arduino Based Countdown Timer

Circuit Diagram :-

Code :- 

//Prateek //wwww.prateeks.in //https://www.youtube.com/c/JustDoElectronics/videos #include <LiquidCrystal.h> #include "Countimer.h" Countimer tdown; LiquidCrystal lcd(12, 11, 10, 9, 8, 7); #include <EEPROM.h> #define bt_set A3 #define bt_up A2 #define bt_down A1 #define bt_start A0 int time_s = 0; int time_m = 0; int time_h = 0; int set = 0; int flag1=0, flag2=0; int relay = 5; int buzzer = 6; void setup() { Serial.begin (9600); pinMode(bt_set, INPUT_PULLUP); pinMode(bt_up, INPUT_PULLUP); pinMode(bt_down, INPUT_PULLUP); pinMode(bt_start, INPUT_PULLUP); pinMode(relay, OUTPUT); pinMode(buzzer, OUTPUT); lcd.begin(16, 2); lcd.clear(); lcd.setCursor(0,0); lcd.print(" Welcome To "); lcd.setCursor(0,1); lcd.print("Countdown Timer"); tdown.setInterval(print_time, 999); eeprom_read(); delay(1000); lcd.clear(); } void print_time(){ time_s = time_s-1; if(time_s<0){time_s=59; time_m = time_m-1;} if(time_m<0){time_m=59; time_h = time_h-1;} } void tdownComplete(){Serial.print("ok");} //tdown.stop(); void loop(){ tdown.run(); if(digitalRead (bt_set) == 0){ if(flag1==0 && flag2==0){flag1=1; set = set+1; if(set>3){set=0;} delay(100); } }else{flag1=0;} if(digitalRead (bt_up) == 0){ if(set==0){tdown.start(); flag2=1;} if(set==1){time_s++;} if(set==2){time_m++;} if(set==3){time_h++;} if(time_s>59){time_s=0;} if(time_m>59){time_m=0;} if(time_h>99){time_h=0;} if(set>0){eeprom_write();} delay(200); } if(digitalRead (bt_down) == 0){ if(set==0){tdown.stop(); flag2=0;} if(set==1){time_s--;} if(set==2){time_m--;} if(set==3){time_h--;} if(time_s<0){time_s=59;} if(time_m<0){time_m=59;} if(time_h<0){time_h=99;} if(set>0){eeprom_write();} delay(200); } if(digitalRead (bt_start) == 0){ flag2=1; eeprom_read(); digitalWrite(relay, HIGH); tdown.restart(); tdown.start(); } lcd.setCursor(0,0); if(set==0){lcd.print(" Timer ");} if(set==1){lcd.print(" Set Timer SS ");} if(set==2){lcd.print(" Set Timer MM ");} if(set==3){lcd.print(" Set Timer HH ");} lcd.setCursor(4,1); if(time_h<=9){lcd.print("0");} lcd.print(time_h); lcd.print(":"); if(time_m<=9){lcd.print("0");} lcd.print(time_m); lcd.print(":"); if(time_s<=9){lcd.print("0");} lcd.print(time_s); lcd.print(" "); if(time_s==0 && time_m==0 && time_h==0 && flag2==1){flag2=0; tdown.stop(); digitalWrite(relay, LOW); digitalWrite(buzzer, HIGH); delay(300); digitalWrite(buzzer, LOW); delay(200); digitalWrite(buzzer, HIGH); delay(300); digitalWrite(buzzer, LOW); delay(200); digitalWrite(buzzer, HIGH); delay(300); digitalWrite(buzzer, LOW); } if(flag2==1){digitalWrite(relay, HIGH);} else{digitalWrite(relay, LOW);} delay(1); } void eeprom_write(){ EEPROM.write(1, time_s); EEPROM.write(2, time_m); EEPROM.write(3, time_h); } void eeprom_read(){ time_s = EEPROM.read(1); time_m = EEPROM.read(2); time_h = EEPROM.read(3); }

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Video :-