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 TypesïGeneric AT command has four types:
Type
Command Format
Description
Test Command
AT+<CommandName>=?
Query the Set Commandsâ internal parameters and their range of values.
Query Command
AT+<CommandName>?
Return the current value of parameters.
Set Command
AT+<CommandName>=<â¦>
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. The characters that need to be escaped are ,, ", and \:
\\: 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 âNew Line Modeâ.
Definitions of AT command error codes are provided in AT API Reference:
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:
AT+UART_DEF: AT+UART_DEF=115200,8,1,0,3
AT+SAVETRANSLINK: AT+SAVETRANSLINK=1,"192.168.6.10",1001
AT+CWAUTOCONN: AT+CWAUTOCONN=1
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 MessagesïThere 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.
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 doesnât 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 ReportsïESP-AT Message Report
Description
ready
The ESP-AT firmware is ready
busy pâ¦
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+CIPRECVTYPE=1.
+IPD,<link_id>,<length> will be outputted if AT+CIPMUX=1 and AT+CIPRECVTYPE=<link_id>,1.
+IPD,<length>:<data> will be outputted if AT+CIPMUX=0, AT+CIPRECVTYPE=0, and AT+CIPDINFO=0.
+IPD,<link_id>,<length>:<data> will be outputted if AT+CIPMUX=1, AT+CIPRECVTYPE=<link_id>,0, and AT+CIPDINFO=0.
+IPD,<length>,<"remote_ip">,<remote_port>:<data> will be outputted if AT+CIPMUX=0, AT+CIPRECVTYPE=0, and AT+CIPDINFO=1.
+IPD,<link_id>,<length>,<"remote_ip">,<remote_port>:<data> will be outputted if AT+CIPMUX=1, AT+CIPRECVTYPE=<link_id>,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+CIPRECVTYPE=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.
Through the Log Output pin described in Hardware Connection, ESP-AT outputs rich log information to help you understand its runtime status. You can also enable different log configurations to view more detailed log information. The following table lists some common log messages and their explanations:
AT Log
Description
at-common: write dlen:0
The RX of the AT command port received unexpected data, usually containing multiple \0 characters. If you are communicating with the MCU via UART, please check the following:
Whether the UART RX pin of ESP32 is correctly connected to the TX pin of the MCU
Whether the MCU is sending data not in AT command format
Whether the MCU is correctly configured for UART baud rate, data bits, stop bits, parity, and flow control
Whether the GND of the MCU is correctly connected to the GND pin of ESP32
at-init: at param mode: <mode>
Parameter mode during AT initialization
0: No parameters
1: Use parameters in the mfg_nvs partition
2: Use parameters in the factory_param partition
at-init: v4.1.0.0 (<src>)
AT firmware version number and the source of the corresponding firmware build
at-wifi: negotiated phy mode: <phy_mode>
PHY mode negotiated when Wi-Fi Station connects to AP
0: Low Rate
1: 11b
2: 11g
3: 11a
4: HT20
5: HT40
6: HE20
7: VHT20
at-wifi: wifi disconnected, rc:<reason_code>
Wi-Fi station disconnection reason code
at-wifi: wifi reconnect..(<index>/<total_count>)
Wi-Fi station is reconnecting to AP
at-net: unknown host: <hostname>
Unable to resolve hostname <hostname>, please check DNS settings and network connection
at-net: send failed, s:<send_len> r:<ret_len>
Failed to send data: expected to send <send_len> bytes, but only <ret_len> bytes were sent. Please check network connection.
at-net: link is changed
When AT is acting as a server, the client connection was interrupted during data transmission, and a new client has connected to the server.
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