ESP32 Smart Door Lock

// ESP32 Smart Door Lock - Intermediate
// Multi-PIN NVS + OLED + tamper lockout + web admin
#include <Keypad.h>
#include <ESP32Servo.h>
#include <Preferences.h>
#include <Wire.h>
#include <Adafruit_SSD1306.h>
#include <WiFi.h>
#include <WebServer.h>
#include <time.h>

const char* SSID="YourSSID";
const char* PASS="YourPassword";

Preferences prefs;
Adafruit_SSD1306 oled(128,64,&Wire,-1);
WebServer server(80);
Servo lockServo;

const byte ROWS=4,COLS=4;
char keys[4][4]={{"1","2","3","A"},{"4","5","6","B"},
                  {"7","8","9","C"},{"*","0","#","D"}};
byte rp[4]={13,12,14,27}, cp[4]={26,25,33,32};
Keypad kpad=Keypad(makeKeymap(keys),rp,cp,ROWS,COLS);

String entered="";
int wrongCount=0;
bool lockedOut=false;
unsigned long lockEnd=0;

bool checkPIN(const String &pin){
  prefs.begin("pins",true);
  int n=prefs.getInt("count",0);
  for(int i=0;i<n;i++){
    if(prefs.getString(String(i).c_str(),"")==pin){
      prefs.end(); return true;
    }
  }
  prefs.end(); return false;
}

void logEvent(const String &msg){
  time_t now=time(nullptr);
  String ts=ctime(&now); ts.trim();
  oled.clearDisplay(); oled.setCursor(0,0);
  oled.println(msg); oled.println(ts); oled.display();
  Serial.println(msg+" "+ts);
}

void setup(){
  Serial.begin(115200);
  Wire.begin(21,22);
  oled.begin(SSD1306_SWITCHCAPVCC,0x3C);
  oled.setTextSize(1); oled.setTextColor(WHITE);
  lockServo.attach(18); lockServo.write(0);
  pinMode(4,OUTPUT);pinMode(2,OUTPUT);pinMode(15,OUTPUT);
  WiFi.begin(SSID,PASS);
  while(WiFi.status()!=WL_CONNECTED) delay(500);
  configTime(0,0,"pool.ntp.org");
  server.on("/",[](){
    server.send(200,"text/html",
      "<h2>Lock Admin</h2>"
      "<form method=POST action=/add><input name=pin><button>Add</button></form>"
      "<form method=POST action=/del><input name=pin><button>Del</button></form>");
  });
  server.begin();
  oled.clearDisplay(); oled.setCursor(0,0);
  oled.print("IP: "); oled.println(WiFi.localIP()); oled.display();
}

void loop(){
  server.handleClient();
  if(lockedOut){
    if(millis()<lockEnd) return;
    lockedOut=false; wrongCount=0;
  }
  char k=kpad.getKey();
  if(!k) return;
  if(k=="#"){
    if(checkPIN(entered)){
      wrongCount=0;
      logEvent("UNLOCKED");
      digitalWrite(4,HIGH); lockServo.write(90);
      delay(3000); lockServo.write(0); digitalWrite(4,LOW);
    } else {
      wrongCount++;
      logEvent("DENIED #"+String(wrongCount));
      digitalWrite(2,HIGH);digitalWrite(15,HIGH);
      delay(800); digitalWrite(2,LOW);digitalWrite(15,LOW);
      if(wrongCount>=3){ lockedOut=true; lockEnd=millis()+30000; }
    }
    entered="";
  } else if(k=="*"){ entered=""; }
  else { entered+=k; }
}