The Microsoft Azure Sphere platform for integrating microcontrollers with the Internet of Things (IoT) includes both the reference architecture for microcontrollers, matching operating systems, and a cloud service that takes care of updates. In this article I help you get started with Azure Sphere.

Digitization and Optimization

The significant trend of digitization is increasingly determining business life. Economic success often depends on a company's ability to map and optimize processes in production and logistics. IoT and its professional offshoot, industrial IoT (IIoT), belong in this context as subsets under the digitization umbrella. IoT provides a link between information technology and the physical world, creating the basis on which software and artificial intelligence (AI) can be applied.

For AI to acquire data in the physical world, measure and draw conclusions from the data, and respond on a physical level, it needs the digital twins of physical assets and software implementation. Conversely, the machines in the physical world need sensors that collect data and actuators that allow software to intervene.

IoT Elements

Devices that operate according to rules different from the classic client-server model are pushing their way into the network, posing new challenges for IT administrators. Although admins have been confronted with a large number of clients and servers in the past, full-fledge digitization of machines and systems quickly adds a large number of new endpoints.

Typically, these endpoints are microcontrollers (MCUs). The smallest representatives of this genre are devices from the Espressif ESP8266 and ESP32 product families, which have been well used and documented [1]. Systems from the Arduino family are also popular. This MCU platform can be programmed in C++ in its integrated development environment (the Arduino IDE), and both the hardware and software are available under an open source license.

The controller is usually installed on a development board, connected directly by USB to a system with an installed IDE. A board like this combines processor, memory, and timer components; a digital-to-analog converter; and connectivity by a wireless local area network (WLAN) or Bluetooth. To further expand functionality, expansion boards known as hardware attached on top (HATs) or shields add sensors, actuators, or small displays to the board. Grove expansion boards are also available as an alternative. A Grove shield routes the MCU's connections out to simple slots so that all other components can be connected with standardized plugin cables and without soldering.

MCUs try to connect to the network over WLAN or a low-power, wide-area network (LoRaWAN) over longer distances. At the logical data transfer level, don't forget legacy HTTP, on which representational state transfer (REST) enables communication to and from IoT devices by common HTTP methods such as GET and POST. Protocols such as the Advanced Message Queuing Protocol (AMQP) and Message Queuing Telemetry Transport (MQTT) protocol are still very common IoT methods. MQTT has minimal overhead and is optimized to allow low-powered devices to transmit data reliably, even over unreliable networks.

MQTT follows the publish-subscribe pattern. Clients can send messages with a certain topic, and other clients subscribe to them in a style known from social networks. The communication hub is an MQTT broker that receives the data and takes care of distributing messages in push mode.

Azure Sphere for Enterprise IoT

Because they are easily accessible, Arduinos and comparable MCUs are popular in the consumer space, but developing on this platform poses challenges once a project needs to scale to production levels. What do you need to consider if you are no longer working with a few prototypes, but a population of hundreds or even thousands of endpoints on your network that can both measure and influence business-critical processes?

In this case, comprehensive distribution of firmware and application updates to the endpoints must be ensured, and securing communications, authentication, and authorization is equally important. This time-consuming activity usually involves dealing with security strategies such as certificate-based encryption, and unfortunately, it is all too often neglected or not taken seriously enough on the fast path from development to production. Microsoft enters the scene for these situations with Azure Sphere [2].

With Azure Sphere, Microsoft creates its own platform for IoT that includes far more than just MCU hardware. Azure Sphere links three vital elements: hardware, software, and cloud service. Safety is not an add-on that needs to be retrofitted at some later stage, but an integral part of the platform right from the outset.