Firstly I have connected the Arduino UNo to Esp8266-01 Module and uploaded the Simple Blink Sketch using Arduino Uno and It responded correctly as in the Blue Led Light on Esp8266-01 was blinking correctly. Now for AT Commands I uploaded Blank Sketch to Arduino Uno and then on serial monitor with baud rate as 115200 typed in AT but no output is seen on Serial Monitor , Please Help Why Esp8266-01 Module not responding to AT Commands

  • 3
    the sketch replaced the AT firmware
    – Juraj
    Commented Jun 19, 2021 at 7:45
  • 1
    When using it as a WiFi modem, you communicate with it using AT-command, and by default that is what most of ESP8266 module does, it shipped with At-command firmware. When you using an ESP8266 as an MCU, you flash the ESP8266 with Arduino sketch, which overrides the AT-Command firmware and upload it with Arduino bootloader, and allow the ESP8266 to be used as a stand-alone MCU like an Arduino.
    – hcheung
    Commented Jun 20, 2021 at 2:51

1 Answer 1


The "AT" commands are provided by a specific sketch (firmware). The chip can only hold one sketch at a time - that sketch currently is your "blink" sketch.

If you want to have AT commands then you have to put the correct AT command firmware on the chip, removing your Blink sketch in the process.

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