M5Stack Atom NB-IoT device with secure MQTT over IPv6

M5Stack produce a suite of pilot-suitable modular IoT devices, including the Atom DTU NB-IoT. The NB-IoT DTU (Narrow Band Internet of Things - data transmission unit) comes in a small 64 24 29mm case with a DIN rail clip on mounting and support for RS-485 including 9-24V power (or USB-C power).

The kit base has a SIM7020G modem and the ESP32-based Atom Lite (which also supports WiFi) is included with a very resonable price. The device has built in MQTT, supports secure public certificate TLS connections, and supports IPv6.

While the physical unit is ready for pilot deployment (and the M5Stack website has several commerical deployment case studies), there is no pre-written firmware for the device, so some up front development is needed.

As well as reviewing the strengths and weaknesses of the device, I will also provide some sample code for a proof-of-concept using an Env III environment sensor to transmit temperature, humidity, and air pressure to an MQTT test server using MQTTS (with server certificates), over IPv6, over NB-IoT.

M5Stack Atom DTU NB-IoT with Telstra SIM card

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Deployment ready NB-IoT device review — Unboxing the Dragino N95S31B

The Dragino NBSN95/NBSN95A family is a deployment-ready range of water resistant NB-IoT (Narrow Band Internet of Things) devices that are available pre-packaged with various sensors such as soil moisture, distance detection, liquid level, and temperature/humidity sensors.

NB-IoT is a Low-Power Wide-Area Network (LPWAN) technology that allows devices to be accessed in remote locations and operate on battery for long periods of time, up to many years.

In this article we will look a the N95S31B, the model with the pre-packaged temperature/humidity sensors, the strengths and weaknesses of the device, and then walk through configuing the device and see it connect to an MQTT test server. Our previous article showed you how to set up an MQTT test server on Azure if needed.

The NBSN95 is an open source project, with both the software and hardware specifications available, if you need to customise the application. We have also previously reviewed the Dragion LDDS75 LoRaWAN device.

Dragino wiring the serial connection

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Deploying a secure MQTT test server on Azure with IPv6

MQTT (originally Message Queuing Telemetry Transport) is an important protocol for IoT that has been widely adopted. Devices deployed to the field may be connecting to existing MQTT endpoints, however you may also want to deploy your own MQTT server for testing purposes.

This article shows you how to deploy an Eclipse Mosquitto MQTT server onto Azure, configured for secure connections (MQTTS, which is MQTT over TLS), accessible over the internet, and including support for both IPv6 and legacy IPv4.

First we will configure a network in Azure, then deploy the server, and then test the deployment.

The instructions below show the individual commands, but if you want a quick start then full scripts, with automatic parameters, are available on Github https://github.com/sgryphon/iot-demo-build/blob/main/azure-mosquitto/README-mosquitto.md

To deploy the network and then server components via the scripts:

az login
az account set --subscription <subscription id>
$VerbosePreference = 'Continue'
./azure-landing/infrastructure/deploy-network.ps1
./azure-mosquitto/infrastructure/deploy-mosquitto.ps1 YourSecretPassword

Read on for the full details.

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