AT Command Set

Here is a list of AT commands. Some of the AT commands can only work on the ESP32, which is marked as [ESP32 Only]; others can work on both the ESP8266 and ESP32.

Before checking the command set details, please review some common information on command types, configurations that can be saved in the flash, as well as messages returned after entering commands.

AT Command Types

Generic AT command has four types:

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

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

  • Square brackets [ ] designate parameters that may be omitted; default value of the parameter will be used instead.

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

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

  • If the parameter which is not the last one is omitted, you can give a , to indicate it.

    Example:

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

  • String values need to be included in double quotation marks, for example: AT+CWSAP="ESP756290","21030826",1,4.

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

    • \\: escape backslash itself

    • \,: escape comma which is used to separate each parameter

    • \": escape double quotation marks which 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.

  • AT commands are ended with a new-line (CR-LF), so the serial tool should be set into “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. Please see description of AT+SYSSTORE for details.

AT Messages

There are two types of ESP-AT messages from ESP-AT command port. One is ESP-AT command response Messages passively, the other is ESP-AT message report actively.

ESP-AT Response Messages
Any ESP-AT command input will return the response by mandatory, it tells the sender the result of the ESP-AT command.
ESP-AT Message Report
ESP-AT will report the system important state change or message.
ESP-AT Response Messages
AT Response Messages Description
OK AT command process done and return OK
ERROR AT command error or error occurred during execution
SEND OK Data has been sent to the protocol stack (Unique to AT+CIPSEND and AT+CIPSENDEX command)
SEND FAIL Error occurred during sending the data to the protocol stack (Unique to AT+CIPSEND and AT+CIPSENDEX command)
+<Command Name>:... Response to the sender that AT command process result in detail
ESP-AT Message Report
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, CAN NOT accept the newly 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 WiFi
WIFI CONNECTED WiFi station interface has connected to an AP
WIFI GOT IP WiFi station interface has got the IPv4 address
WIFI DISCONNECT WiFi 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 WiFi softAP interface of ESP-AT
+DIST_STA_IP: <sta_mac>,<sta_ip> The WiFi softAP interface of ESP-AT distributes an IP address to the station
+STA_DISCONNECTED: <sta_mac> A station disconnected from the WiFi 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 transparent transmission
Have <xxx> Connections Has reached the maximum connection counts for server
+QUITT ESP-AT quits from the transparent transmission mode
NO CERT FOUND No a valid device certificate found in custom partition
NO PRVT_KEY FOUND No a valid private key found in custom partition
NO CA FOUND No a 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 BLE connection established
+BLEDISCONN A BLE connection ends
+READ A read operation from BLE connection
+WRITE A write operation from BLE connection
+NOTIFY A notification from BLE connection
+INDICATE An indication from BLE connection
+BLESECNTFYKEY BLE SMP key
+BLEAUTHCMPL BLE SMP pairing completed