AT Command Set

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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; those without any mark can work on all ESP series, including ESP32, ESP8266, ESP32-S2, and ESP32-C3.

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.

  • Currently, only strings and integer numbers are supported as input parameters in AT commands.

  • Angle brackets < > designate parameters that can not be omitted.

  • 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.

    AT+CWJAP="ssid","password",,1
    
  • String values need to be included in double quotation marks.

    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
  • Escape is needed in AT commands only, not elsewhere. For example, when AT command port prints > and wait for your input, the input does not need to be escaped.

    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:

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, which is mentioned in the Note section of these commands.

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 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). It doesn’t mean that the data has been sent to the opposite end
    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 (active)

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

    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 commands
    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 GOT IPv6 LL Wi-Fi station interface has got the IPv6 LinkLocal address
    WIFI GOT IPv6 GL Wi-Fi station interface has got the IPv6 Global address
    WIFI DISCONNECT Wi-Fi station interface has disconnected from an AP
    +ETH_CONNECTED Ethernet interface has connected
    +ETH_GOT_IP Ethernet interface has got the IPv4 address
    +ETH_DISCONNECTED Ethernet 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 MQTT 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