LPWA - Protocol MQTT
- Nikolay Henneberg
Owned by Nikolay Henneberg
The MQTT protocol defines a lightweight and simple messaging protocol designed for limited devices and networks with low bandwidth, unreliable networks or high latency. The MQTT client uses publish and subscribe methods to communicate over a TCP connection with the MQTT message broker.
MQTT AT commands are implemented according to MQTT version 3.1.1.
Secure MQTT is not supported
1. Example: Unencrypted, unauthenticated
# Translates a domain name into an IP address using an existing DNS.
> AT+UDNSRN=0,"broker.emqx.io"
< +UDNSRN: "3.82.39.163", "44.195.202.69"
< OK
# Enable URCs
> AT+CEREG=2
< OK
# Read network registration status
> AT+CEREG?
< +CEREG: 2,2
< OK
# Read network registration status. Wait of +CEREG: 2,5...
> AT+CEREG?
< +CEREG: 2,5,"AB80","819965",9
< OK
# Check the module connected to the network
> AT+CGATT?
< +CGATT: 1
< OK
# Check to see if the PDP context has been activated.
> AT+CGACT?
< +CGACT: 1,1
< OK
# Read IP address from module
> AT+CGDCONT?
< +CGDCONT: 1,"IP","vgesace.nb.iot","10.254.46.241",0,0,0,0,0,0
< OK
# Set MQTT unique client ID. In the example IMEI from device
> AT+UMQTT=0,"350857128129037"
< +UMQTT: 0,1
< OK
# Set MQTT local TCP port number
> AT+UMQTT=1,1883
< +UMQTT: 1,1
< OK
# Set remote MQTT server's name
> AT+UMQTT=2,"broker.emqx.io"
< +UMQTT: 2,1
< OK
# Set remote MQTT server's IP address
> AT+UMQTT=3,"44.195.202.69",1883
< +UMQTT: 3,1
< OK
# Connect to the broker
> AT+UMQTTC=1
< +UMQTTC: 1,1
< OK
< +UUMQTTC: 1,0
""" Repeat the command "AT+UMQTTC=1" if the URC "+UUMQTTC: 1,0" does not arrive. """
# Subscribe to MQTT topic filter
> AT+UMQTTC=4,0,"/exelonix/test"
< +UMQTTC: 4,1
< OK
< +UUMQTTC: 4,1,0,"/exelonix/test"
# Publish MQTT message to topic name
> AT+UMQTTC=2,0,0,"/exelonix/test","MQTT message"
< +UMQTTC: 2,1
< OK
# Wait of asynchronous notification (URC) of the reception of an MQTT message
< +UUMQTTCM: 6,1
# Read MQTT messages received
> AT+UMQTTC=6
< +UMQTTC: 6,1
< OK
< +UUMQTTCM: 6,1
< Topic:/exelonix/test
< Msg:MQTT message
# Disconnect from the broker
> AT+UMQTTC=0
< +UMQTTC: 0,1
< OK2. Example: Unencrypted, authenticated
# Translates a domain name into an IP address using an existing DNS.
> AT+UDNSRN=0,"test.mosquitto.org"
< +UDNSRN: "91.121.93.94"
< OK
# Enable URCs
> AT+CEREG=2
< OK
# Read network registration status
> AT+CEREG?
< +CEREG: 2,2
< OK
# Read network registration status. Wait of +CEREG: 2,5...
> AT+CEREG?
< +CEREG: 2,5,"A9F0","819901",7
< OK
# Check the module connected to the network
> AT+CGATT?
< +CGATT: 1
< OK
# Check to see if the PDP context has been activated.
> AT+CGACT?
< +CGACT: 1,1
< OK
# Read IP address from module
> AT+CGDCONT?
< +CGDCONT: 1,"IP","vgesace.nb.iot","10.254.46.27",0,0,0,0,0,0
< OK
# Set MQTT unique client ID. In the example IMEI from device
AT+UMQTT=0,"350857128129037"
+UMQTT: 0,1
OK
# Set MQTT local TCP port number
AT+UMQTT=1,1884
+UMQTT: 1,1
OK
# Set remote MQTT server's name
AT+UMQTT=2,"test.mosquitto.org"
+UMQTT: 2,1
OK
# Set remote MQTT server's IP address
AT+UMQTT=3,"91.121.93.94",1884
+UMQTT: 3,1
OK
# Set User name and password
AT+UMQTT=4,"rw","readwrite"
+UMQTT: 4,1
OK
# Connect to the broker
AT+UMQTTC=1
+UMQTTC: 1,1
OK
+UUMQTTC: 1,0
""" Repeat the command "AT+UMQTTC=1" if the URC "+UUMQTTC: 1,0" does not arrive. """
# Subscribe to MQTT topic filter
AT+UMQTTC=4,0,"/exelonix/test"
+UMQTTC: 4,1
OK
+UUMQTTC: 4,1,0,"/exelonix/test"
# Publish MQTT message to topic name
AT+UMQTTC=2,0,0,"/exelonix/test","MQTT message"
+UMQTTC: 2,1
OK
# Wait of asynchronous notification (URC) of the reception of an MQTT message
+UUMQTTCM: 6,1
# Read MQTT messages received
AT+UMQTTC=6
+UMQTTC: 6,1
OK
+UUMQTTCM: 6,1
Topic:/exelonix/test
Msg:MQTT message
# Disconnect from the broker
> AT+UMQTTC=0
< +UMQTTC: 0,1
< OK