Being a newbie to Arduino, I'm trying to implement AT commands in the serial monitor, though in vain. After connecting the ESP8266 (01) module to an Arduino Uno, I tried to scan for the nearest network present [code link: https://github.com/esp8266/Arduino/blob/master/doc/esp8266wifi/scan-examples.md#simple-scan] and it worked perfectly.

But the moment I am trying to connect to send AT commands (even manually), it shows nothing. In addition, if(Serial.available()) and if(esp8266.available())< both are giving false value.

What am I doing wrong?

  • Show your code, since maybe the problem lies with Softserial + native serial
    – duck
    Dec 30, 2016 at 7:42

2 Answers 2


You don't give a circuit diagram or very much detail about what you've done, but if I guess correctly...

You have flashed the code in your link to the ESP-01 (perhaps using the Arduino as a serial port adapter). That code is now running on the ESP itself - it's not running on the Arduino and controlling the ESP.

Flashing the ESP erases the stock firmware, so the ESP can no longer respond to AT commands.

I don't know of a way to reprogram the 'AT' firmware into the ESP but perhaps Google will help.

If I've guessed incorrectly, please explain exactly what you have done - with circuit diagram, setup steps and code.

  • This is exactly what has happened. I reprogram the 'AT' firmware into the ESP then AT was working perfectly. The moment I tried to access ESP programmatically [sendData("AT+CWMODE=2\r\n",1000,DEBUG)] it again showed the same problem. I think Program Address Offset [Hex] value for firmware and my *.ino are same. I am trying another range with no result. Can you tell me how to change the Program Offset for Aurduino [0x000000]. Any able comment is solicited. Jan 2, 2017 at 5:56
  • If my answer answers your original question, please feel free to accept it, and optionally up-vote it. That will encourage people to answer further questions. If you have a new question, please read stackoverflow.com/help/how-to-ask and ask a new question.
    – Mark Smith
    Jan 2, 2017 at 9:08
  • created a new thread, please assist there as well. [ref: arduino.stackexchange.com/questions/32899/… Jan 2, 2017 at 10:28

Anyone who is new to using ESP8266 module should consider following before interfacing it with Arduino

  1. Try connecting ESP Module directly with your computer and test out all the AT Commands you will be implementing with Arduino. This approach is better because (a) this will give you confidence that your communication works perfectly (b) you will figure out all the problems that people face when sending AT commands and receive reply (c) this is a more visual approach so you will know what is going on and where you are going wrong.

  2. Use Computer based communication tools and make a simple power adaptor to solve communication and wiring problems once and for all.

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