AT Commands for ESP8266: Where and How to use them

The Hayes command set or AT commands are instructions used to control a modem, but the default firmware of ESP8266 also allows us to use AT commands to communicate with ESP8266.

AT is the abbreviation of Attention. Every command line starts with “AT” or “at”. Note that the starting “AT” is the prefix that informs the modem about the start of a command line. It is not part of the AT command name. For example, +GMR is the actual AT command name in AT+GMR. However, some people and web sites use them interchangeably as the name of an AT command.

At_COMMAND

Here is a list of AT commands which you can use to communicate with ESP8266 (you can send these commands via Arduino/MCU to drive ESP8266). There are two types of AT commands – basic commands(commands that do not start with “+”) and extended commands(commands that start with “+”).

Basic commands are AT commands that do not start with “+”. For example, D (Dial), A (Answer), H (Hook control) and O (Return to online data state) are basic commands. Rest are extended commands explained below :

Commands Description Set/Execute Parameters
AT+RST restart the module
AT+CWMODE wifi mode AT+CWMODE=<mode> 1= Sta, 2= AP, 3=both
AT+CWJAP join the AP AT+ CWJAP =<ssid>,< pwd > ssid = ssid, pwd = wifi password
AT+CWLAP list the AP AT+CWLAP
AT+CWQAP quit the AP AT+CWQAP
AT+ CWSAP set the parameters of AP AT+ CWSAP= <ssid>,<pwd>,<chl>, <ecn> ssid, pwd, chl = channel, ecn = encryption
AT+ CIPSTATUS get the connection status AT+ CIPSTATUS
AT+CIPSTART set up TCP or UDP connection 1)single connection (+CIPMUX=0) AT+CIPSTART= <type>,<addr>,<port>; 2) multiple connection (+CIPMUX=1) AT+CIPSTART= <id><type>,<addr>, <port> id = 0-4, type = TCP/UDP, addr = IP address, port= port
AT+CIPSEND send data 1)single connection(+CIPMUX=0) AT+CIPSEND=<length>; 2) multiple connection (+CIPMUX=1) AT+CIPSEND= <id>,<length>
AT+CIPCLOSE close TCP or UDP connection AT+CIPCLOSE=<id> or AT+CIPCLOSE
AT+CIFSR Get IP address AT+CIFSR
AT+ CIPMUX set mutiple connection AT+ CIPMUX=<mode> 0 for single connection 1 for mutiple connection
AT+ CIPSERVER set as server AT+ CIPSERVER= <mode>[,<port> ] mode 0 to close server mode, mode 1 to open; port = port
+IPD received data

A brief list of AT commands can be found HERE

Comprehensive list of AT commands can be found HERE

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