Code for Bluetooth Controlled LED using ESP32.

Bluetooth-Controlled-LED-ESP32.ino

#include <BluetoothSerial.h>

#define ledPIN 2
BluetoothSerial SerialBT;
byte BTData;

/* Check if Bluetooth configurations are enabled in the SDK */
#if !defined(CONFIG_BT_ENABLED) || !defined(CONFIG_BLUEDROID_ENABLED)
#error Bluetooth is not enabled! Please run `make menuconfig` to and enable it
#endif

void setup()
{
  pinMode(ledPIN, OUTPUT);
  Serial.begin(115200);
  SerialBT.begin();
  Serial.println("Bluetooth Started! Ready to pair...");
}

void loop()
{
  if(SerialBT.available())
  {
    BTData = SerialBT.read();
    Serial.write(BTData);
  }

  /* If received Character is 1, then turn ON the LED */
  /* You can also compare the received data with decimal equivalent */
  /* 48 for 0 and 49 for 1 */
  /* if(BTData == 48) or if(BTData == 49) */
  if(BTData == '1')
  {
    digitalWrite(ledPIN, HIGH);
  }
  
  /* If received Character is 0, then turn OFF the LED */
  if(BTData == '0')
  {
    digitalWrite(ledPIN, LOW);
  }
}