ESP32 Real-Time Clock

#include <Arduino.h>
#include <Wire.h>
#include <RTClib.h>
#include <LiquidCrystal_I2C.h>
#include <EEPROM.h>
RTC_DS1307 rtc;
LiquidCrystal_I2C lcd(0x27,16,2);
const uint8_t BUZZER=9;
// Hai nut noi D2/D3 xuong GND. Nhan ca hai de doi che do.
struct Button {
 uint8_t pin; bool raw=true, down=false; uint32_t changed=0;
 Button(uint8_t p):pin(p){}
 bool update(){bool r=digitalRead(pin); if(r!=raw){raw=r;changed=millis();}
 bool released=false; if(millis()-changed>=30 && down==raw){released=down;down=!raw;} return released;}
} h(2),m(3);
enum Mode {VIEW,SET_TIME,SET_YEAR,SET_DATE,SET_ALARM};
Mode mode=VIEW;
uint8_t ah=6,am=0; bool enabled=true,showMessage=false,combo=false,ringing=false;
uint32_t lastAlarm=0xffffffffUL,ringStart=0;
char message[17]="CHUC BAN NGAY VUI";
char previous[2][17]={{0},{0}};
void save(){EEPROM.update(0,0xA7);EEPROM.update(1,ah);EEPROM.update(2,am);EEPROM.update(3,enabled); for(uint8_t i=0;i<16;i++)EEPROM.update(4+i,message[i]);}
void row(uint8_t n,const char* text){char padded[17];memset(padded,' ',16);padded[16]=0;memcpy(padded,text,min((size_t)16,strlen(text)));if(strcmp(previous[n],padded)){lcd.setCursor(0,n);lcd.print(padded);strcpy(previous[n],padded);}}
bool monitorEnabled=false;
void status(){
 DateTime t=rtc.now();char line[100];
 snprintf(line,sizeof(line),"TIME %04u-%02u-%02u %02u:%02u:%02u ALARM %02u:%02u %s RING %u MODE %u",
 t.year(),t.month(),t.day(),t.hour(),t.minute(),t.second(),ah,am,enabled?"ON":"OFF",ringing,(unsigned)mode);
 Serial.println(line);
}
void serialCommand(char* text){
 unsigned y,mo,d,hh,mm,ss;int end=0;
 if(!strcmp(text,"HELP")) Serial.println(F("HELP | PING | STATUS | TIME YYYY-MM-DD HH:MM:SS | ALARM HH:MM | ON | OFF | STOP | MON ON | MON OFF | MSG text"));
 else if(!strcmp(text,"PING")) Serial.println(F("OK PONG"));
 else if(!strcmp(text,"STATUS")) status();
 else if(!strcmp(text,"MON ON")){monitorEnabled=true;Serial.println(F("OK MON ON"));}
 else if(!strcmp(text,"MON OFF")){monitorEnabled=false;Serial.println(F("OK MON OFF"));}
 else if(!strcmp(text,"ON")||!strcmp(text,"OFF")){enabled=!strcmp(text,"ON");save();Serial.println(F("OK"));}
 else if(!strcmp(text,"STOP")){ringing=false;noTone(BUZZER);lastAlarm=rtc.now().unixtime()/60;Serial.println(F("OK STOP"));}
 else if(!strncmp(text,"TIME ",5)){
  bool valid=strlen(text)==24 && sscanf(text+5,"%4u-%2u-%2u %2u:%2u:%2u%n",&y,&mo,&d,&hh,&mm,&ss,&end)==6 && end==19;
  const uint8_t days[]={31,28,31,30,31,30,31,31,30,31,30,31};
  valid=valid && y>=2000 && y<=2099 && mo>=1 && mo<=12 && d>=1 && hh<24 && mm<60 && ss<60;
  if(valid) valid=d<=days[mo-1]+((mo==2 && y%4==0)?1:0);
  if(valid){rtc.adjust(DateTime(y,mo,d,hh,mm,ss));lastAlarm=0xffffffffUL;Serial.println(F("OK TIME"));}
  else Serial.println(F("ERR TIME: YYYY-MM-DD HH:MM:SS, years 2000-2099"));
 }
 else if(!strncmp(text,"ALARM ",6)){
  if(strlen(text)==11 && sscanf(text+6,"%2u:%2u%n",&hh,&mm,&end)==2 && end==5 && hh<24 && mm<60){ah=hh;am=mm;save();Serial.println(F("OK ALARM"));}
  else Serial.println(F("ERR ALARM: HH:MM"));
 }
 else {
  const char* value=!strncmp(text,"MSG ",4)?text+4:text;
  size_t n=strlen(value);
  if(n>16 || !n){Serial.println(F("ERR message: 1-16 ASCII characters"));return;}
  memset(message,' ',16);memcpy(message,value,n);message[16]=0;save();Serial.println(F("OK MSG"));
 }
}
void readSerial(){
 static char input[64];static uint8_t length=0;static bool overflow=false;
 while(Serial.available()){
  char c=Serial.read();
  if(c=='\r'||c=='\n'){
   if(overflow)Serial.println(F("ERR line too long or non-ASCII"));
   else if(length){input[length]=0;serialCommand(input);}
   length=0;overflow=false;
  }else if(c>=32 && c<=126 && length<sizeof(input)-1)input[length++]=c;
  else overflow=true;
 }
}
void setup(){
 pinMode(2,INPUT_PULLUP);pinMode(3,INPUT_PULLUP);pinMode(BUZZER,OUTPUT);digitalWrite(BUZZER,LOW);
 Serial.begin(9600);Wire.begin();lcd.init();lcd.backlight();
 if(!rtc.begin()){row(0,"RTC not found");Serial.println(F("ERR RTC not found: check 5V, GND, SDA A4, SCL A5"));while(true)delay(100);}
 if(!rtc.isrunning())rtc.adjust(DateTime(F(__DATE__),F(__TIME__)));
 if(EEPROM.read(0)==0xA7 && EEPROM.read(1)<24 && EEPROM.read(2)<60 && EEPROM.read(3)<2){ah=EEPROM.read(1);am=EEPROM.read(2);enabled=EEPROM.read(3);for(uint8_t i=0;i<16;i++){char c=EEPROM.read(4+i);message[i]=(c>=32&&c<=126)?c:' ';}message[16]=0;}
 Serial.println(F("READY 9600 baud. Send HELP, end with Enter."));
}
void loop(){
 bool hr=h.update(),mr=m.update();bool both=h.down&&m.down;
 bool stopped=false;
 if(ringing&&(h.down||m.down)){ringing=false;noTone(BUZZER);combo=true;stopped=true;}
 if(both&&!combo&&!stopped){combo=true;mode=Mode((mode+1)%5);save();}
 if(combo){hr=mr=false;if(!h.down&&!m.down)combo=false;}
 DateTime now=rtc.now();
 if(hr||mr){
  if(mode==VIEW){if(hr){enabled=!enabled;save();}if(mr)showMessage=!showMessage;}
  else if(mode==SET_ALARM){if(hr)ah=(ah+1)%24;if(mr)am=(am+1)%60;save();}
  else {
   uint16_t y=now.year();uint8_t mo=now.month(),d=now.day(),hh=now.hour(),mm=now.minute();
   if(mode==SET_TIME){if(hr)hh=(hh+1)%24;if(mr)mm=(mm+1)%60;}
   if(mode==SET_YEAR){if(hr)y=y>=2099?2000:y+1;if(mr)y=y<=2000?2099:y-1;}
   if(mode==SET_DATE){if(hr)mo=mo%12+1;}
   const uint8_t days[]={31,28,31,30,31,30,31,31,30,31,30,31};
   uint8_t maxday=days[mo-1]+((mo==2&&y%4==0)?1:0);
   if(mode==SET_DATE&&mr)d=d>=maxday?1:d+1;
   if(d>maxday)d=maxday;
   rtc.adjust(DateTime(y,mo,d,hh,mm,0));now=rtc.now();
  }
 }
 uint32_t minuteKey=now.unixtime()/60;
 if(enabled&&mode==VIEW&&now.hour()==ah&&now.minute()==am&&lastAlarm!=minuteKey){lastAlarm=minuteKey;ringing=true;ringStart=millis();}
 if(ringing&&(millis()-ringStart>=60000UL||!enabled)){ringing=false;noTone(BUZZER);}
 static bool sounding=false;bool beep=ringing&&((millis()-ringStart)%1000<500);
 if(beep!=sounding){sounding=beep;if(beep)tone(BUZZER,4000);else noTone(BUZZER);}
 readSerial();
 static uint32_t lastReport=0;
 if(monitorEnabled && millis()-lastReport>=1000){lastReport=millis();status();}
 char a[32],b[32];
 if(ringing){snprintf(a,sizeof(a),"BAO THUC %02u:%02u",ah,am);strcpy(b,"Nhan nut de tat");}
 else if(mode==VIEW){if(showMessage)strcpy(a,message);else snprintf(a,sizeof(a),"%02u/%02u/%04u",now.day(),now.month(),now.year());snprintf(b,sizeof(b),"%02u:%02u:%02u %c%02u:%02u",now.hour(),now.minute(),now.second(),enabled?'A':'-',ah,am);}
 else if(mode==SET_ALARM){strcpy(a,"CAI BAO THUC");snprintf(b,sizeof(b),"%02u:%02u %s",ah,am,enabled?"ON":"OFF");}
 else {strcpy(a,mode==SET_TIME?"CAI GIO / PHUT":mode==SET_YEAR?"CAI NAM + / -":"CAI THANG / NGAY");if(mode==SET_TIME)snprintf(b,sizeof(b),"%02u:%02u:%02u",now.hour(),now.minute(),now.second());else snprintf(b,sizeof(b),"%02u/%02u/%04u",now.day(),now.month(),now.year());}
 row(0,a);row(1,b);delay(5);
}