#include <SoftwareSerial.h>

SoftwareSerial bluetooth(10, 11); // RX, TX

void setup() {
  Serial.begin(9600);    // Serial monitor
  bluetooth.begin(9600); // Bluetooth module
  pinMode(13, OUTPUT);    // Output pin for controlling the switch
}

void loop() {
  if (bluetooth.available()) {
    char command = bluetooth.read();

    // Check the received command
    if (command == '1') {
      digitalWrite(13, HIGH); // Turn on the switch
    } else if (command == '0') {
      digitalWrite(13, LOW);  // Turn off the switch
    }
  }
}