MQTT Flex with LARA-R6, SARA-R5 and SARA-R422

You can follow the instructions in the AT Commands Manual for how to use the MQTT-SN Client and security profiles.:

• LARA-R6 AT Commands Manual

• SARA-R5 AT Commands Manual 

• SARA-R4 AT Commands Manual

Some simple examples to get you up and running quickly are listed below.

Configure the module

• Specify the client key and certificate to be used
  
  This example assumes you have saved the client key and certificate generated by the Thingstream platform for your Flex Thing to the file system of the SARA module using the AT+UDWNFILE command using the file names device.pem for the certificate and device.key for the key.
  
  AT+USECMNG=1,1,"MQTTFlex_cert","device.pem"
  
  AT+USECMNG=1,2,"MQTTFlex_key", "device.key"
  
  

• Configure the DTLS security profile
  
  The following commands  set up the DTLS security profile which the  MQTT-SN client will make use of.
  
  Set the profile ID to use.  This examples uses profile 0:
  AT+USECPRF=0
  Set the certificate validation level:
  AT+USECPRF=0,0,0
  Set profile 0 to accept TLS v1.2:
  AT+USECPRF=0,1,3
  Set the cipher suite:
  AT+USECPRF=0,2,99,"C0","30"
  Set the  client key and certificate to be used (as created in the previous step):
  AT+USECPRF=0,5,"MQTTFlex_cert"
  AT+USECPRF=0,6,"MQTTFlex_key"
  
  

• Configure the MQTT-SN  client to use your MQTT Flex thing with the security profile
  
  Set the  client ID (copy from Thingstream portal):
  AT+UMQTTSN=0,"device:xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"
  Configure the MQTT-SN gateway endpoint:
  AT+UMQTTSN=1,"mqtt-flex.thingstream.io",2443
  Set the client to use the required DTLS profile:
  AT+UMQTTSN=9,1,0
  
  

• Save configuration
  
  AT+UMQTTSNNV=2
  
  

• Load configuration
  
  AT+UMQTTSNNV=1
  
  

Using the MQTT-SN Client

Once you have completed the MQTT-SN client configuration, you will need to set up the packet switched data configuration to use the APN specified by your MNO.  You can then proceed with the MQTT-SN commands e.g.

• Connect
  
  AT+UMQTTSNC=1
  Expect +UUMQTTSNC: 1,1 as a response to confirm you are connected.  You should also see a green dot next to your Thing in the management console.

• Register a topic
  
  Before you can publish to a  normal topic, you need to register with with the broker and get back a topic ID.
  
  AT+UMQTTSNC=2,"my/publish/topic"
  Expect +UUMQTTSNC: 2,1,1 as a response to confirm the registration.  The final argument in the response is the topic ID to use when you publish.

• Publish
  
  AT+UMQTTSNC=4,1,0,0,0,"1","My message"
  Expect +UUMQTTSNC: 4,1 as a response to confirm the publish.  You will also now see a new device originated message in the activity tab for your Thing in the management console.

To receive messages on your module, you need to subscribe to a topic.

• Subscribe
  
  AT+UMQTTSNC=5,1,0,"my/subscribe/topic"
  Expect +UUMQTTSNC: 5,1,0,1 as a response to confirm you have subscribed.  You will also now see a new subscription in the activity tab for your Thing in the management console.

Now if you publish a message to "my/subscribe/topic " you will see it arrive on the  module.  You can use the "Send Message" function in the management console to send a test message.  Check out the guide here to see how.

• Read  a received message
  
  When the message arrives, you'll see +UUMQTTSNC: 9,1 in the terminal.  You can read the message with the following command.
  
  AT+UMQTTSNC=9,1