diff --git a/src/BLE/ERaBLEDevice.hpp b/src/BLE/ERaBLEDevice.hpp
new file mode 100644
index 0000000..81f9d61
--- /dev/null
+++ b/src/BLE/ERaBLEDevice.hpp
@@ -0,0 +1,170 @@
+#include <Arduino.h>
+#include <BLEDevice.h>
+#include <BLEUtils.h>
+#include <BLEServer.h>
+#include <MD5Builder.h>
+#include <LinkedList.h>
+
+const int ledPin = 2;  // this is for debug, can remove
+
+#define CODE "1d91d980-bbe4-4db4-8790-829a2fc62450"  // this is chip code, keeping there
+#define DEVICE_NAME "E-Ra - Trung Thu"  // this is nothing
+
+#define SERVICE_UUID "c459d382-3ecd-41a2-8769-c502dbb88648"  // this is bluetooth address
+#define PASSWORD "f01f1e6b-e404-4534-bdfd-58af0e1fbb59"  // this is bluetooth password
+#define CHARACTERISTIC_CONFIRM_CODE_UUID "6ee26cfb-b42f-43ae-9ecf-f70d84bbd64f"  // this is E-Ra constant, not change
+#define CHARACTERISTIC_CONTROL_UUID "f0e7aa38-e466-42af-b4c7-5e6ec5c9a614"  // this is E-Ra constant, not change
+
+
+char** verifiedCodes = new char*[5];  // max
+u_int8_t verifiedCount = 0;
+LinkedList<uint16_t> verifiedConnectionId = LinkedList<uint16_t>();
+BLEServer *pServer = nullptr;
+
+
+class MyServerCallbacks: public BLEServerCallbacks {
+  void onConnect(BLEServer* pServer, esp_ble_gatts_cb_param_t *param) {
+    Serial.print("Connected BLE");
+    Serial.println(param->connect.conn_id);
+    pServer->startAdvertising();  // accepting more than 1 connection
+  };
+  void onDisconnect(BLEServer* pServer, esp_ble_gatts_cb_param_t *param) {
+    Serial.print("Disconnected BLE");
+    Serial.println(param->connect.conn_id);
+    pServer->startAdvertising();  // accepting more than 1 connection
+    verifiedConnectionId.remove(param->connect.conn_id);  // remove trusted connection
+  }
+};
+
+
+class ControlCallbacks: public BLECharacteristicCallbacks {
+    void onWrite(BLECharacteristic *pCharacteristic, esp_ble_gatts_cb_param_t* param) {
+      // check permission before control
+      int size = verifiedConnectionId.size();
+      bool hasPermission = false;
+      for (int i = 0; i < size; i++) {
+        if (verifiedConnectionId.get(i) == param->connect.conn_id) {
+          hasPermission = true;
+          break;
+        }
+      }
+      if (!hasPermission) {
+        Serial.println("NO PERMISSION");
+        return;
+
+      }
+      std::string message = pCharacteristic->getValue();
+      Serial.println(message.c_str());
+      u_int8_t index = message.find(';'); // <pin>;<value> reduce message size because bluetooth is slow
+      const char* pinStr = message.substr(0, index).c_str();
+      const char* value = message.substr(index + 1).c_str();
+
+      // handle case virtual pin later
+      u_int8_t pin = atoi(pinStr);
+      pinMode(pin, OUTPUT);  // should put in setup or setup characteristic
+      digitalWrite(pin, atoi(value));
+    }
+};
+
+
+class ConfirmCallbacks: public BLECharacteristicCallbacks {
+  char currentVerificationCode[9];
+  void onWrite(BLECharacteristic *pCharacteristic, esp_ble_gatts_cb_param_t* param) {
+    if (verifiedCount >= 5) {  // hardware define max connection accept, this is not a big problem
+      pCharacteristic->setValue("Max connections.");
+      pCharacteristic->notify();  // no need to notify
+      return;
+    }
+    
+    std::string value = pCharacteristic->getValue();
+
+    Serial.println(value.c_str());
+
+    if (value == "start") {
+      // random code and write back
+      currentVerificationCode[0] = (char) (esp_random() % 26 + '0');
+      currentVerificationCode[1] = (char) (esp_random() % 26 + '0');
+      currentVerificationCode[2] = (char) (esp_random() % 26 + '0');
+      currentVerificationCode[3] = (char) (esp_random() % 26 + '0');
+      currentVerificationCode[4] = (char) (esp_random() % 26 + '0');
+      currentVerificationCode[5] = (char) (esp_random() % 26 + '0');
+      currentVerificationCode[6] = (char) (esp_random() % 26 + '0');
+      currentVerificationCode[7] = (char) (esp_random() % 26 + '0');
+      currentVerificationCode[8] = 0;
+
+      Serial.println(currentVerificationCode);
+      pCharacteristic->setValue(currentVerificationCode);
+      pCharacteristic->notify();
+    }
+
+    if (value.substr(0, 7) == "confirm") {  // using string for shorten message
+      char code[36 + 8 + 1]; // uuid4 + random + endstring
+      for(int i = 0; i < 36; i++) {
+        code[i] = PASSWORD[i];
+      }
+      for (int i = 0; i < 8; i++) {
+        code[36 + i] = currentVerificationCode[i];
+      }
+      code[44] = 0;
+
+      MD5Builder md5;
+      md5.begin();
+      md5.add(code);
+      md5.calculate();
+
+      char* output = new char[33];  // can use char output[33] instead
+      md5.getChars(output);
+
+      Serial.println("verified code");
+      Serial.println(output);
+
+      if (value.substr(7, 32) == output) {
+        digitalWrite(ledPin, HIGH);
+        pCharacteristic->setValue("confirmed");
+        verifiedConnectionId.add(param->connect.conn_id);
+      } else {
+        digitalWrite(ledPin, LOW);
+        
+        Serial.print("Disconnecting BLE");  // not correct then disconnect
+        Serial.println(param->disconnect.conn_id);
+        pServer->disconnect(param->disconnect.conn_id);
+      }
+      delete output;
+    }
+  }
+};
+
+void setup() {
+  Serial.begin(9600);
+  pinMode(ledPin, OUTPUT);
+
+  BLEDevice::init(DEVICE_NAME);
+  pServer = BLEDevice::createServer();
+  pServer->setCallbacks(new MyServerCallbacks());
+  BLEService *pService = pServer->createService(SERVICE_UUID);
+
+  BLECharacteristic *confirmCharacteristic = pService->createCharacteristic(
+    CHARACTERISTIC_CONFIRM_CODE_UUID,
+    BLECharacteristic::PROPERTY_READ | 
+    BLECharacteristic::PROPERTY_WRITE |
+    BLECharacteristic::PROPERTY_NOTIFY
+  );
+  confirmCharacteristic->setCallbacks(new ConfirmCallbacks());
+  
+
+  BLECharacteristic *controlCharacteristic = pService->createCharacteristic(
+    CHARACTERISTIC_CONTROL_UUID,
+    BLECharacteristic::PROPERTY_READ | 
+    BLECharacteristic::PROPERTY_WRITE |
+    BLECharacteristic::PROPERTY_NOTIFY
+  );
+  controlCharacteristic->setCallbacks(new ControlCallbacks());
+
+  pService->start();
+  BLEAdvertising *pAdvertising = pServer->getAdvertising();
+  pAdvertising->addServiceUUID(SERVICE_UUID);
+  pAdvertising->start();
+}
+
+void loop() {
+}
\ No newline at end of file