AT Command Set

Here is a list of AT commands. Some of them can only work on the ESP32 series, so they are marked as [ESP32 Only] at the beginning; others without any mark can work on both the ESP8266 and ESP32 series.

It is strongly recommended to read the following sections for some common information on AT commands before you dive into the details of each command.

AT Command Types

Generic AT command has four types:

Type Command Format Description
Test Command AT+<CommamdName>=? Query the Set Commands’ internal parameters and their range of values.
Query Command AT+<CommamdName>? Return the current value of parameters.
Set Command AT+<CommamdName>=<…> Set the value of user-defined parameters in commands, and run these commands.
Execute Command AT+<CommamdName> Run commands with no user-defined parameters.

  • Not all AT commands support all of the four types mentioned above.

  • Square brackets [ ] designate parameters that can be omitted. The default value of the parameter will be used instead when you omit it.

    Below are examples of entering the command AT+CWJAP with some parameters omitted:

    AT+CWJAP="ssid","password"
AT+CWJAP="ssid","password","11:22:33:44:55:66"

  • If the parameter you want to omit is followed by a parameter(s), you must give a , to indicate it.

    Example:

    AT+CWJAP="ssid","password",,1

  • String values need to be included in double quotation marks.

    Example:

    AT+CWSAP="ESP756290","21030826",1,4

  • Escape character syntax is needed if a string contains special characters, such as ,, ", or \:

    • \\: escape the backslash itself
    • \,: escape comma which is not used to separate each parameter
    • \": escape double quotation mark which is not used to mark string input
    • \<any>: escape <any> character means that drop backslash symbol and only use <any> character

    Example:

    AT+CWJAP="comma\,backslash\\ssid","1234567890"
AT+MQTTPUB=0,"topic","\"{\"sensor\":012}\"",1,0

  • The default baud rate of AT command is 115200.

  • The length of each AT command should be no more than 256 bytes.

  • AT commands end with a new-line (CR-LF), so the serial tool should be set to “New Line Mode”.

  • Definitions of AT command error codes are provided in AT API Reference:

    • esp_at_error_code
    • esp_at_para_parse_result_type
    • esp_at_result_code_string_index

AT Commands with Configuration Saved in the Flash

Configuration settings entered by the following AT Commands will always be saved in the flash NVS Area, so they can be automatically restored on reset:

Saving of configuration settings by several other commands can be switched on or off with AT+SYSSTORE command.

AT Messages

There are two types of ESP-AT messages returned from the ESP-AT command port:

  • ESP-AT Response Messages (passive)

    Each ESP-AT command input returns response messages to tell the sender the result of the ESP-AT command.

  • ESP-AT Message Reports (active)

    ESP-AT will report important state changes or messages in the system.

ESP-AT Response Messages
AT Response Messages Description
OK AT command process done and return OK
ERROR AT command error or error occurred during the execution
SEND OK Data has been sent to the protocol stack (specific to AT+CIPSEND and AT+CIPSENDEX command)
SEND FAIL Error occurred during sending the data to the protocol stack (specific to AT+CIPSEND and AT+CIPSENDEX command
+<Command Name>:... Response to the sender that describes AT command process results in details
ESP-AT Message Reports
ESP-AT Message Report Description
ready The ESP-AT firmware is ready
busy p… Busy processing. The system is in process of handling the previous command, thus CANNOT accept the new input
ERR CODE:<0x%08x> Error code for different command
Will force to restart!!! Module restart right now
smartconfig type:<xxx> Smartconfig type
Smart get wifi info Smartconfig has got the SSID and PASSWORD information
smartconfig connected wifi Smartconfig done. ESP-AT has connected to the Wi-Fi
WIFI CONNECTED Wi-Fi station interface has connected to an AP
WIFI GOT IP Wi-Fi station interface has got the IPv4 address
WIFI DISCONNECT Wi-Fi station interface has disconnected from an AP
+ETH_CONNECTED Ethernet station interface has connected
+ETH_GOT_IP Ethernet station interface has got the IPv4 address
+ETH_DISCONNECTED Ethernet station interface has disconnected
[<conn_id>,]CONNECT A network connection of which ID is <conn_id> is established (ID=0 by default)
[<conn_id>,]CLOSED A network connection of which ID is <conn_id> ends (ID=0 by default)
+LINK_CONN Detailed connection information of TCP/UDP/SSL
+STA_CONNECTED: <sta_mac> A station has connected to the Wi-Fi softAP interface of ESP-AT
+DIST_STA_IP: <sta_mac>,<sta_ip> The Wi-Fi softAP interface of ESP-AT distributes an IP address to the station
+STA_DISCONNECTED: <sta_mac> A station disconnected from the Wi-Fi softAP interface of ESP-AT
> ESP-AT is waiting for more data to be received
Recv <xxx> bytes ESP-AT has already received <xxx> bytes from the ESP-AT command port
+IPD ESP-AT received the data from the network
SEND Canceled Cancel to send in Wi-Fi passthrough mode
Have <xxx> Connections Has reached the maximum connection counts for server
+QUITT ESP-AT quits from the Wi-Fi passthrough mode
NO CERT FOUND No valid device certificate found in custom partition
NO PRVT_KEY FOUND No valid private key found in custom partition
NO CA FOUND No valid CA certificate found in custom partition
+MQTTCONNECTED MQTT connected to the broker
+MQTTDISCONNECTED MQTTT disconnected from the broker
+MQTTSUBRECV MQTT received the data from the broker
+MQTTPUB:FAIL MQTT failed to publish data
+MQTTPUB:OK MQTT publish data done
+BLECONN A Bluetooth LE connection established
+BLEDISCONN A Bluetooth LE connection ends
+READ A read operation from Bluetooth LE connection
+WRITE A write operation from Bluetooth LE connection
+NOTIFY A notification from Bluetooth LE connection
+INDICATE An indication from Bluetooth LE connection
+BLESECNTFYKEY Bluetooth LE SMP key
+BLEAUTHCMPL Bluetooth LE SMP pairing completed

Provide feedback about this document