/* 
 *  Bluetooth module PRO
 * 
 *  Copyright (C) Libelium Comunicaciones Distribuidas S.L.
 *  http://www.libelium.com
 * 
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 * 
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 * 
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see http://www.gnu.org/licenses/.
 * 
 *  Version:           1.0
 *  Design:            David Gascón
 *  Implementation:    Luis Miguel Martí
 */

byte pinleds[] = {3,4,5,6,7,8};

char error[] = "SYNTAX ERROR";
char devices[400];
char dev;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  delay(1000);
  Serial.print("Configurando...");
  while (sendATcommand("AT", "OK", error, 1000) == 2);
  while (sendATcommand("SET BT AUTH * 0000", "", error, 1000) == 2);

  Serial.print("Iniciando...");
  delay(1000);
  for (byte i=0;i<6;i++){
  pinMode(pinleds[i],OUTPUT);
  }
}

void loop() {
  // put your main code here, to run repeatedly:
  memset(devices, NULL , 400);
  dev = askForDevices();
  Serial.print("Number of devices: ");
  Serial.println(dev);
  for (byte i=0;i<dev-48;i++){
    digitalWrite(pinleds[i],HIGH);
  }
  for(byte i=dev-48;i<6;i++){
    digitalWrite(pinleds[i],LOW);
  }
}

int8_t sendATcommand(char* ATcommand, char* expected_answer, char* error_answer, unsigned int timeout) {
  uint8_t x = 0,  answer = 0;
  char response[100];
  unsigned long previous;
  memset(response, '\0', 100);    // Initialize the string
  delay(100);
  while ( Serial.available() > 0) Serial.read();   // Clean the input buffer
  Serial.println(ATcommand);    // Send the AT command
  x = 0;
  previous = millis();
  do {
    if (Serial.available() != 0) {
      response[x] = Serial.read();
      x++;
      if (strstr(response, expected_answer) != NULL) {
        answer = 1;
        Serial.println("Expected response");
      } else if (strstr(response, error_answer) != NULL) {
        answer = 2;
      }
    }
    // Waits for the asnwer with time out
  }
  while ((answer == 0) && ((millis() - previous) < timeout));
  return answer;
}

char askForDevices () {

  Serial.println("Searching...");
  delay(500);
  while (Serial.available() > 0) {
    Serial.read();
  }
  delay(500);
  while (Serial.available() > 0) {
    Serial.read();
  }
  delay(500);
  while (Serial.available() > 0) {
    Serial.read();
  }
  Serial.println("INQUIRY 3");

  uint32_t time = millis();
  uint16_t i = 0;
  while (millis()-time<4000){
   
    while (Serial.available()>0){
      devices[i] = char(Serial.read());
      delay(10);
      i++;
    }
   
  }
  delay(1000);

  boolean go_on = true;
  uint16_t counter = 15;
  while (go_on) {
   
    if (devices[counter-15] == 'E') {
      if (devices[counter + 1-15] == 'R') {
        if (devices[counter + 2-15] == 'R') {
          if (devices[counter + 3-15] == 'O') {
            if (devices[counter + 4-15] == 'R') {
                  return '0';
            }
          }
        }
      }
    }
               
   
    if (devices[counter] == 'I') {
      if (devices[counter + 1] == 'N') {
        if (devices[counter + 2] == 'Q') {
          if (devices[counter + 3] == 'U') {
            if (devices[counter + 4] == 'I') {
              if (devices[counter + 5] == 'R') {
                if (devices[counter + 6] == 'Y') {
                  if (devices[counter + 7] == ' ') {
                    go_on = false;
                  } else counter++;
                } else counter++;
              } else counter++;
            } else counter++;
          } else counter++;
        } else counter++;
      } else counter++;
    } else counter++;
  }
  return devices[counter + 8];
}
       

https://www.cooking-hacks.com/documentation/tutorials/arduino-bluetooth/