AT Command Set

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Here is a list of AT commands.

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+<CommandName>=?

Query the Set Commands’ internal parameters and their range of values.

Query Command

AT+<CommandName>?

Return the current value of parameters.

Set Command

AT+<CommandName>=<…>

Set the value of user-defined parameters in commands, and run these commands.

Execute Command

AT+<CommandName>

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 optional 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.

Note

The parameters of AT commands are saved based on NVS library. Therefore, if the command is configured with the same parameter value, flash will not be written; If the command is configured with the different parameter value, flash will not be erased frequently.

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. The last message in the response is either OK or ERROR.

    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

    SET OK

    The URL has been set successfully (specific to AT+HTTPURLCFG 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

    +SCRD:<length>,``<reserved data>``

    ESP-Touch v2 has got the reserved 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 when AT is not in Passthrough Mode. The message formats are as follows:

    • +IPD,<length> will be outputted if AT+CIPMUX=0 and AT+CIPRECVMODE=1.

    • +IPD,<link_id>,<length> will be outputted if AT+CIPMUX=1 and AT+CIPRECVMODE=1.

    • +IPD,<length>:<data> will be outputted if AT+CIPMUX=0, AT+CIPRECVMODE=0, and AT+CIPDINFO=0.

    • +IPD,<link_id>,<length>:<data> will be outputted if AT+CIPMUX=1, AT+CIPRECVMODE=0, and AT+CIPDINFO=0.

    • +IPD,<length>,<"remote_ip">,<remote_port>:<data> will be outputted if AT+CIPMUX=0, AT+CIPRECVMODE=0, and AT+CIPDINFO=1.

    • +IPD,<link_id>,<length>,<"remote_ip">,<remote_port>:<data> will be outputted if AT+CIPMUX=1, AT+CIPRECVMODE=0, and AT+CIPDINFO=1.

    The link_id represents the connection ID, length indicates the data length, remote_ip refers to the remote IP address, remote_port represents the remote port number, and data denotes the actual data.

    Note: In the case of a SSL connection, in passive receive mode (AT+CIPRECVMODE=1), the length in the AT command response may not match the actual readable SSL data length. This is because AT prioritizes returning the readable data length at the SSL layer. If the SSL layer has no readable data, AT will return the readable data length at the socket layer.

    The Data in Passthrough Mode

    ESP-AT received the data from the network or Bluetooth when AT is in Passthrough Mode

    SEND Canceled

    Cancel to send in Wi-Fi normal sending 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

    +TIME_UPDATED

    The system time has been updated. Only after sending the AT+CIPSNTPCFG command or power on will this message be outputted if the module fetches a new time from the SNTP server.

    +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

    +BLESECREQ:<conn_index>

    Received encryption request which index is <conn_index>

    +BLEAUTHCMPL:<conn_index>,<enc_result>

    Bluetooth LE SMP pairing completed

    +BLUFIDATA:<len>,<data>

    The ESP device received customized data from the phone over BluFi

    +WS_DISCONNECTED:<link_id>

    The WebSocket connection of ID <link_id> is disconnected.

    +WS_CONNECTED:<link_id>

    The WebSocket connection of ID <link_id> is established.

    +WS_DATA:<link_id>,<data_len>,<data>

    The Websocket connection of ID <link_id> has received the data.

    +WS_CLOSED:<link_id>

    The WebSocket connection of ID <link_id> is closed.

    +BLESCANDONE

    Scan finished

    +BLESECKEYREQ:<conn_index>

    The peer has accepted the pairing request, and the ESP device can enter the key.

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