AT Command Set

The ESP8266 was introduced about three years ago. At first the only software for it was based on its AT Command Set. Many of the example programs found on the internet are based on it.

Over the months Espressif Systems have released upgrades to the AT Command Set. In a few cases certain commands have been removed. In other cases the response has changed. The net result is that a sketch that was found on the internet, while it may have worked perfectly for the author, may generate errors if a different version of the AT Command Set is programmed into your ESP8266. This leads to much debugging frustration.

I encourage all authors to record the version of the AT commend set they are using in a comment near the beginning of their sketch.

The documentation for the latest versions can be found on the Espressif website but docs for older versions are harder to find. To ease the search I have posted several below.  I recently found a wiki with the binaries of all the older versions of the AT Command Set.  Unhappily additions were discontinued in July 2015.


Ver 0.20

Ver. 0.21

Ver 0.24
Ver 0.30
Ver 0.40
Since the release of ESP8266_NONOS_SDK_V1.5.0, AT firmware is too large to use 4Mbit flash. Please choose flash with at least 8Mbit capacity.
Ver 1.40
Ver 1.53
Ver 1.54
Ver 2.0.0

Ver 2.1.0


Ver 2.2.2


I recently received a NodeMCU from that didn't seem to have a normal AT Command Set at all.  On power up I got (9600 baud):

NodeMcu 0.9.6 ( Version) build 20150701  powered by Lua 5.1.4
ESP8266 Started
Start soft AP

When I tried the AT+RST command I got:

stdin:1: '=' expected near '+'

I have no idea what that means and I don't know it is programmed into any ESP8266 ESP-01 modules.


This page written by Roger Schaefer. Last updated March 19, 2018