MQTT AT Command Set

AT Application: https://github.com/espressif/esp-at
AT Documentation: https://github.com/espressif/esp-at/tree/master/docs

After commit: 8ebdee924 , ESP-AT support MQTT AT commands. Users developing applications based on AT may refer to commands below, for quick connection with corresponding Broker using AT+MQTT.

** Before using AT+MQTT, please enable AT+MQTT function:**
make menuconfig -> Component config -> AT -> AT MQTT command support

Command List

AT+MQTTUSERCFG - Configure MQTT user attributes
AT+MQTTCONNCFG - Configure MQTT connection attributes
AT+MQTTCONN - Connect to/search MQTT Broker
AT+MQTTPUB - Publish text strings
AT+MQTTPUBRAW - Publish binaries
AT+MQTTSUB - Subscribe/search themes
AT+MQTTUNSUB - Unsubscribe themes
AT+MQTTCLEAN - Disconnect MQTT Broker

AT+MQTTUSERCFG - Configure MQTT user attributes

Set Command:

AT+MQTTUSERCFG=<LinkID>,<scheme>,<"client_id">,<"username">,<"password">,<cert_key_ID>,<CA_ID>,<"path">

Function:
Set up MQTT user configuration

Response:

OK

ERROR

Parameter Description:

LinkID: Currently only support 0
scheme:
- 1: MQTT over TCP
- 2: MQTT over TLS(no certificate verify)
- 3: MQTT over TLS(verify server certificate)
- 4: MQTT over TLS(provide client certificate)
- 5: MQTT over TLS(verify server certificate and provide client certificate)
- 6: MQTT over WebSocket(based on TCP)
- 7: MQTT over WebSocket Secure(based on TLS, no certificate verify)
- 8: MQTT over WebSocket Secure(based on TLS, verify server certificate)
- 9: MQTT over WebSocket Secure(based on TLS, provide client certificate)
- 10: MQTT over WebSocket Secure(based on TLS, verify server certificate and provide client certificate)
client_id: ID of MQTT client, served as a symbol of identity, 256 bytes at most
username: username to log in MQTT broker, 64 bytes at most
password: password to log in MQTT broker, 64 bytes at most
cert_key_ID: ID of certificate. Currently only support one cert certificate, whose parameter is 0
CA_ID: CA ID. Currently only support one CA certicate, whose parameter is 0
path: Resource path, 32 bytes at most

AT+MQTTCONNCFG - Configure MQTT connection attributes

Set Command:

AT+MQTTCONNCFG=<LinkID>,<keepalive>,<disable_clean_session>,<"lwt_topic">,<"lwt_msg">,<lwt_qos>,<lwt_retain>

Function:
Set up MQTT connection configuration

Response:

OK

ERROR

Parameter Descrption:

LinkID: Currently only support 0
keepalive: MQTT PING timeout limits, ranging from 60 seconds to 7200 seconds. Default = 120
disable_clean_session: MQTT clean session. The optional values of this parameter are 0 and 1 (default = 0)
lwt_topic: Will topic, 64 bytes at most
lwt_msg: Will message, 64 bytes at most
lwt_qos: Will QoS. The optional values of this parameter are 0, 1 and 2 (default = 0)
lwt_retain: Will retain. The optional values of this parameter are 0 and 1 (default = 0)

AT+MQTTCONN

Set Command:

AT+MQTTCONN=<LinkID>,<"host">,<port>,<reconnect>

Function:
Connect to the specified MQTT broker

Response:

OK

ERROR

Query Command:

AT+MQTTCONN?

Function:
Query for MQTT brokers already connected to AT

Response:

+MQTTCONN:<LinkID>,<state>,<scheme><"host">,<port>,<"path">,<reconnect>
OK

Parameter Descrption:

LinkID: Currently only support 0
host: Domain name of the MQTT broker to be connected, 128 bytes at most
port: Port to connect MQTT broker, 65535 at most
path: Resource path, 32 bytes at most
reconnect: Reconnect to MQTT. If this parameter is set to 1, more memory resources will be consumed
state: Current status of MQTT:
- 0: Connection is not initialized
- 1: MQTTUSERCFG has been set
- 2: MQTTCONNCFG has been set
- 3: Connection has been broken
- 4: Connection has been established
- 5: Connected, but topic has not been subscribed
- 6: Connected, and topic has been subscribed
scheme:
- 1: MQTT over TCP
- 2: MQTT over TLS(no certificate verify)
- 3: MQTT over TLS(verify server certificate)
- 4: MQTT over TLS(provide client certificate)
- 5: MQTT over TLS(verify server certificate and provide client certificate)
- 6: MQTT over WebSocket(based on TCP)
- 7: MQTT over WebSocket Secure(based on TLS, no certificate verify)
- 8: MQTT over WebSocket Secure(based on TLS, verify server certificate)
- 9: MQTT over WebSocket Secure(based on TLS, provide client certificate)
- 10: MQTT over WebSocket Secure(based on TLS, verify server certificate and provide client certificate)

AT+MQTTPUB

Set Command:

AT+MQTTPUB=<LinkID>,<"topic">,<"data">,<qos>,<retain>

Function:
Publish string data on LinkID to a topic. To publish binary data, please use AT+MQTTPUBRAW

Response:

OK

ERROR

Parameter Descrption:

LinkID: Currently only support 0
topic: Topic of published messages, 64 bytes at most
data: Message published. Please make sure that data does not contain \0, and AT+MQTTPUB does not exceed the length limit of AT commands
qos: Quality of service. The optional values of this parameter are 0, 1 and 2 (default = 0)
retain: retain

AT+MQTTPUBRAW

Set Command:

AT+MQTTPUBRAW=<LinkID>,<"topic">,<length>,<qos>,<retain>

Function:
Publish binary data on LinkID to a topic

Response:

OK
>

ERROR

Response to input of length bytes of data:

+MQTTPUB:FAIL

+MQTTPUB:OK

Parameter Descrption:

LinkID: Currently only support 0
topic: Topic of the message, 64 bytes at most
length: Length of the message to be published. This parameter can be configured via MQTT_BUFFER_SIZE_BYTE of make menuconfig (default = 1024)
qos: Quality of service. The optional values of this parameter are 0, 1 and 2 (default = 0)
retain: retain

AT port will wait until it receives data of the specified length. Data received during the waiting period will be regarded as ordinary data

AT+MQTTSUB

Set Command:

AT+MQTTSUB=<LinkID>,<"topic">,<qos>

Function:
Subscribe the specified MQTT topic. You can subscribe different topic for many times

Response:

OK

ERROR

When a MQTT message of a subscribed topic is received, the content of this message will be printed as follows

+MQTTSUBRECV:<LinkID>,<"topic">,<data_length>,data

If a topic is subscribed repeatedly, the subscription request will still be sent to MQTT broker, and ALREADY SUBSCRIBE will be printed in the log

Query Command:

AT+MQTTSUB?

Function:
Query for all the subscribed MQTT topic

Response:

+MQTTSUB:<LinkID>,<state>,<"topic1">,<qos>
+MQTTSUB:<LinkID>,<state>,<"topic2">,<qos>
+MQTTSUB:<LinkID>,<state>,<"topic3">,<qos>
...
OK

ERROR

Parameter Descrption:

LinkID: Currently only support 0
state: The current status of MQTT:
- 0: Connection is not initialized
- 1: MQTTUSERCFG has been set
- 2: MQTTCONNCFG has been set
- 3: Connection has been broken
- 4: Connection has been established
- 5: Connected, but topic has not been subscribed
- 6: Connected, and topic has been subscribed
topic*: Topics subscribed
qos: QoS subscribed

AT+MQTTUNSUB

Set Command:

AT+MQTTUNSUB=<LinkID>,<"topic">

Function:
Unsubscribe the specified MQTT topic. You can unsubscribe different topic for many times

Response:

OK

ERROR

Parameter Descrption:

LinkID: Currently only support 0
topic: Unsubscribe themes, 64 bytes at most

If a topic is unsubscribed repeatedly, the unsubscription request will still be sent to MQTT broker, and NO UNSUBSCRIBE will be printed in the log

AT+MQTTCLEAN

Set Command:

AT+MQTTCLEAN=<LinkID>

Function:
Disconnect MQTT Client, and release occupied resources

Response:

OK

ERROR

Parameter Descrption:

LinkID: Currently only support 0

MQTT Status Code

If you encounter ERR CODE:0x<%08x> when configuring MQTT, please check the following MQTT status code.

    AT_MQTT_NO_CONFIGURED,                              // 0x6001
    AT_MQTT_NOT_IN_CONFIGURED_STATE,                    // 0x6002
    AT_MQTT_UNINITIATED_OR_ALREADY_CLEAN,               // 0x6003
    AT_MQTT_ALREADY_CONNECTED,                          // 0x6004
    AT_MQTT_MALLOC_FAILED,                              // 0x6005
    AT_MQTT_NULL_LINK,                                  // 0x6006
    AT_MQTT_NULL_PARAMTER,                              // 0x6007
    AT_MQTT_PARAMETER_COUNTS_IS_WRONG,                  // 0x6008
    AT_MQTT_TLS_CONFIG_ERROR,                           // 0x6009
    AT_MQTT_PARAM_PREPARE_ERROR,                        // 0x600A
    AT_MQTT_CLIENT_START_FAILED,                        // 0x600B
    AT_MQTT_CLIENT_PUBLISH_FAILED,                      // 0x600C
    AT_MQTT_CLIENT_SUBSCRIBE_FAILED,                    // 0x600D
    AT_MQTT_CLIENT_UNSUBSCRIBE_FAILED,                  // 0x600E
    AT_MQTT_CLIENT_DISCONNECT_FAILED,                   // 0x600F
    AT_MQTT_LINK_ID_READ_FAILED,                        // 0x6010
    AT_MQTT_LINK_ID_VALUE_IS_WRONG,                     // 0x6011
    AT_MQTT_SCHEME_READ_FAILED,                         // 0x6012
    AT_MQTT_SCHEME_VALUE_IS_WRONG,                      // 0x6013
    AT_MQTT_CLIENT_ID_READ_FAILED,                      // 0x6014
    AT_MQTT_CLIENT_ID_IS_NULL,                          // 0x6015
    AT_MQTT_CLIENT_ID_IS_OVERLENGTH,                    // 0x6016
    AT_MQTT_USERNAME_READ_FAILED,                       // 0x6017
    AT_MQTT_USERNAME_IS_NULL,                           // 0x6018
    AT_MQTT_USERNAME_IS_OVERLENGTH,                     // 0x6019
    AT_MQTT_PASSWORD_READ_FAILED,                       // 0x601A
    AT_MQTT_PASSWORD_IS_NULL,                           // 0x601B
    AT_MQTT_PASSWORD_IS_OVERLENGTH,                     // 0x601C
    AT_MQTT_CERT_KEY_ID_READ_FAILED,                    // 0x601D
    AT_MQTT_CERT_KEY_ID_VALUE_IS_WRONG,                 // 0x601E
    AT_MQTT_CA_ID_READ_FAILED,                          // 0x601F
    AT_MQTT_CA_ID_VALUE_IS_WRONG,                       // 0x6020
    AT_MQTT_CA_LENGTH_ERROR,                            // 0x6021
    AT_MQTT_CA_READ_FAILED,                             // 0x6022
    AT_MQTT_CERT_LENGTH_ERROR,                          // 0x6023
    AT_MQTT_CERT_READ_FAILED,                           // 0x6024
    AT_MQTT_KEY_LENGTH_ERROR,                           // 0x6025
    AT_MQTT_KEY_READ_FAILED,                            // 0x6026
    AT_MQTT_PATH_READ_FAILED,                           // 0x6027
    AT_MQTT_PATH_IS_NULL,                               // 0x6028
    AT_MQTT_PATH_IS_OVERLENGTH,                         // 0x6029
    AT_MQTT_VERSION_READ_FAILED,                        // 0x602A
    AT_MQTT_KEEPALIVE_READ_FAILED,                      // 0x602B
    AT_MQTT_KEEPALIVE_IS_NULL,                          // 0x602C
    AT_MQTT_KEEPALIVE_VALUE_IS_WRONG,                   // 0x602D
    AT_MQTT_DISABLE_CLEAN_SESSION_READ_FAILED,          // 0x602E
    AT_MQTT_DISABLE_CLEAN_SESSION_VALUE_IS_WRONG,       // 0x602F
    AT_MQTT_LWT_TOPIC_READ_FAILED,                      // 0x6030
    AT_MQTT_LWT_TOPIC_IS_NULL,                          // 0x6031
    AT_MQTT_LWT_TOPIC_IS_OVERLENGTH,                    // 0x6032
    AT_MQTT_LWT_MSG_READ_FAILED,                        // 0x6033
    AT_MQTT_LWT_MSG_IS_NULL,                            // 0x6034
    AT_MQTT_LWT_MSG_IS_OVERLENGTH,                      // 0x6035
    AT_MQTT_LWT_QOS_READ_FAILED,                        // 0x6036
    AT_MQTT_LWT_QOS_VALUE_IS_WRONG,                     // 0x6037
    AT_MQTT_LWT_RETAIN_READ_FAILED,                     // 0x6038
    AT_MQTT_LWT_RETAIN_VALUE_IS_WRONG,                  // 0x6039
    AT_MQTT_HOST_READ_FAILED,                           // 0x603A
    AT_MQTT_HOST_IS_NULL,                               // 0x603B
    AT_MQTT_HOST_IS_OVERLENGTH,                         // 0x603C
    AT_MQTT_PORT_READ_FAILED,                           // 0x603D
    AT_MQTT_PORT_VALUE_IS_WRONG,                        // 0x603E
    AT_MQTT_RECONNECT_READ_FAILED,                      // 0x603F
    AT_MQTT_RECONNECT_VALUE_IS_WRONG,                   // 0x6040
    AT_MQTT_TOPIC_READ_FAILED,                          // 0x6041
    AT_MQTT_TOPIC_IS_NULL,                              // 0x6042
    AT_MQTT_TOPIC_IS_OVERLENGTH,                        // 0x6043
    AT_MQTT_DATA_READ_FAILED,                           // 0x6044
    AT_MQTT_DATA_IS_NULL,                               // 0x6045
    AT_MQTT_DATA_IS_OVERLENGTH,                         // 0x6046
    AT_MQTT_QOS_READ_FAILED,                            // 0x6047
    AT_MQTT_QOS_VALUE_IS_WRONG,                         // 0x6048
    AT_MQTT_RETAIN_READ_FAILED,                         // 0x6049
    AT_MQTT_RETAIN_VALUE_IS_WRONG,                      // 0x604A
    AT_MQTT_PUBLISH_LENGTH_READ_FAILED,                 // 0x604B
    AT_MQTT_PUBLISH_LENGTH_VALUE_IS_WRONG,              // 0x604C
    AT_MQTT_RECV_LENGTH_IS_WRONG,                       // 0x604D
    AT_MQTT_CREATE_SEMA_FAILED,                         // 0x604E
    AT_MQTT_CREATE_EVENT_GROUP_FAILED,                  // 0x604F

Notes

Except AT+MQTTCONN, all MQTT commands will return within 10 seconds. For instance, if you the router cannot be connected to the Internet, AT+MQTTPUB will return within 10 seconds.
For AT+MQTTCONN connection based on TLS, the timeout value for each step is 10 seconds, and the total timeout depends on the number of interaction steps.
Once connection to MQTT is broken, +MQTTDISCONNECTED:<LinkID> will be printed
Once connection to MQTT is established, +MQTTCONNECTED:<LinkID>,<scheme>,<"host">,port,<"path">,<reconnect> will be printed

Test Command 1: MQTT over TCP (Need to set up a MQTT broker locally)

When connecting to a MQTT broker using MQTT over TCP(MQTT broker IP: 192.168.31.113 port: 1883), you can subscribe and publish to topic as follows:

AT+MQTTUSERCFG=0,1,"ESP32","espressif","1234567890",0,0,""
AT+MQTTCONN=0,"192.168.31.113",1883,0
AT+MQTTSUB=0,"topic",1
AT+MQTTPUB=0,"topic","test",1,0
AT+MQTTCLEAN=0

Test Command 2: MQTT over TLS (Need to set up a MQTT broker locally)

When connecting to a MQTT broker using MQTT over TLS (MQTT broker IP: 192.168.31.113, port: 1883), you can subscribe and publish to topic as follows:

AT+CIPSNTPCFG=1,8,"ntp1.aliyun.com"
AT+CIPSNTPTIME?
AT+MQTTUSERCFG=0,3,"ESP32","espressif","1234567890",0,0,""
AT+MQTTCONNCFG=0,0,0,"lwtt","lwtm",0,0
AT+MQTTCONN=0,"192.168.31.113",1883,0
AT+MQTTSUB=0,"topic",1
AefT+MQTTPUB=0,"topic","test",1,0
AT+MQTTCLEAN=0

Test Command 3: MQTT over WSS

When connecting to MQTT broker: iot.eclipse.org using MQTT over WSS, (open test port for iot.eclipse.org: 443), you can subscribe and publish to topic as follows:

AT+CIPSNTPCFG=1,8,"ntp1.aliyun.com"
AT+CIPSNTPTIME?
AT+MQTTUSERCFG=0,7,"ESP32","espressif","1234567890",0,0,"wss"
AT+MQTTCONN=0,"iot.eclipse.org",443,0
AT+MQTTSUB=0,"topic",1
AT+MQTTPUB=0,"topic","test",1,0
AT+MQTTCLEAN=0

esp-at application: AT-MQTT Command Set

MQTT AT Command Set

AT+MQTTUSERCFG - Configure MQTT user attributes

AT+MQTTCONNCFG - Configure MQTT connection attributes

AT+MQTTCONN

AT+MQTTPUB

AT+MQTTPUBRAW

AT+MQTTSUB

AT+MQTTUNSUB

AT+MQTTCLEAN

MQTT Status Code

Notes

Test Command 1: MQTT over TCP (Need to set up a MQTT broker locally)

Test Command 2: MQTT over TLS (Need to set up a MQTT broker locally)

Test Command 3: MQTT over WSS

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公衆號5月C#/.NET熱文一覽

git 下載大陸鏡像地址

ESP8266/ESP32 基礎篇: 時間同步 SNTP 介紹和使用

ESP-AT 應用: AT+MQTT 對接亞馬遜雲

ESP-AT 系列: AT+MQTT 使用

ESP8266/ESP32: Exception Causes 參考

ESP-AT 系列: BT 命令介紹和使用

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