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  • Author Author: Jan Cumps
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Arduino MKR WAN 1310 integration with The Things Network MQTT

Jan Cumps
Arduino MKR WAN 1310 integration with The Things Network MQTT

I connected an Arduino MKR WAN 1310 to The Things Network. Then tested if the Arduino uplinks are published on TTN MQTT service. And if I can publish a downlink message on that service too. This post is my log of the activity.

image
image source: me

Read this post first:  Arduino MKR WAN 1310 on The Things Network (TTN) . This posts starts at the point where the Arduino is working with The Things Network (TTN). 

The Example setup

An Arduino MKR WAN 1310 is registered and tested on TTN ( Arduino MKR WAN 1310 on The Things Network (TTN) ). 
TTN MQTT service integration is enabled.
Data that the Arduino uplinks via LoRaWan, arrives on a TTN MQTT topic.
Data that's published to a topic on that TTN MQTT service, arrives on the Arduino as a downlink.

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Earlier, I showed how to integrate with the AWS IoT MQTT service. That allows you to use your data with all AWS services.
This is simpler. It's a direct integration within the TTN network. You can use an MQTT client (or Node-RED, ...) to exchange messages.

Assumptions:

Steps:

  • enable integration of your TTN application with the MQTT service
  • configure an MQTT client
  • test uplink to MQTT and
  • test downlink from MQTT

We don't have to change the Arduino code or modify existing TTN setup. The integration is (same as with AWS before) an extension, not a modification.

Enable TTN to MQTT integration

Enable the integration and set up a password

The integration is actually enabled by default. You just need to get an access key for your client. From the TTN console, open your application, and navigate to Integrations -> MQTT.  The console shows all settings you need, except for the password. Generate that.

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Take care to copy the key and store it in a safe place. It 'll be your MQTT password.

Test the integration with TTN MQTT

TTN has written a good manual for that too: TTN MQTT Server. I followed the exact steps and it worked. I downloaded MQTTX as test client. In a real application, you could use Node-RED flows...

Take over the settings from your console. The password is the one you saved a few steps ago when generating the new API key. Set the MQTT version to 3.1.1. Else the client connection will fail.

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Connect.

uplink from Arduino

To see incoming messages, Subscribe to topic v3/*****-01@ttn/devices/****7/up. (pattern: v3/{application id}/devices/{device id}/up).As soon as your Arduino sends a message over LoRaWan, it will appear in MQTT log . Here's a capture of an incoming payload:

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That works. The payload is JSON, because we provided an uplink formatter in our TTN device setup.

downlink to Arduino

We can test that with MQTTX too. Publish a message to the v3/********-01@ttn/devices/*************7/down/push topic. (pattern: v3/{application id}/devices/{device id}/down/push)

Payload:

{
  "downlinks": [{
    "f_port": 1,
    "decoded_payload": {
      "ledState": "on"
    },
    "priority": "NORMAL"
  }]
}

We can also use JSON here, because we have a downlink formatter in TTN.

The message will immediately appear in the live data log in the TTN console

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But will not yet arrive on the Arduino. That's because we'll only get downlink data when we start a communication (design choice in my sketch). Once we receive an uplink from the Arduino, the downlink is sent back:

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And the LED will light up Slight smile

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One more exercise:  Arduino MKR WAN 1310 integration with Node-RED via The Things Network .

Enjoy.