A little while ago i tried using AT commands on my HC05 bluetooth module using my arduino mega 2560 and it worked fine , skipping a few weeks ahead i tried doing the same , only now i suddenly doesn't work , i tried replacing the arduino and HC05 module , even used the same script for the commands. So i unplugged the module's VCC , pressed the button on the module , reconnected the VCC and the module was blinking every 2 seconds (it's in AT mode !) , now i go ahead to the serial monitor and using that script i typed the command i wanted to execute and it just didn't do nothing , i saw the serial LED on the arduino blink , but nothing was written in the serial monitor and nothing was changed in the arduino.

Does anyone know how to solve this ? it worked perfect before , but now it wont D:

2 Answers 2


Maybe you should try a couple of different baud rates for your script? Also check that your RX/TX wires are connected in the right order. I've had some HC-05 modules where RX/TX markings on the module were reversed.


Here's the solution! First, you have to wire the board like the solution 2 in the instruction. http://www.elecfreaks.com/wiki/index.php?title=Bluetooth_Shield Then, Use this code!

 **  Description:                                                    **
 **  This file is a sample code for your reference.                  **
 **                                                                  **
 **  Copyright (C) 2011 ElecFreaks Corp.                             **
 **  Created by ElecFreaks Robi.W /29 Sep 2011                      **
 **                                                                  **
 **  http://www.elecfreaks.com                                       **
void setup()


void loop()
  int i = 0;
  char someChar[32] = {0};
  // when characters arrive over the serial port...
  if(Serial.available()) {
    Serial.print("------->  ");
      someChar[i++] = Serial.read();
      //As data trickles in from your serial port you are grabbing as much as you can, 
      //but then when it runs out (as it will after a few bytes because the processor 
  //is much faster than a 9600 baud device) you exit loop, which then
 // restarts, 
  //and resets i to zero, and someChar to an empty array.So please be sure to keep this delay 
    }while (Serial.available() > 0);


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