Azure RTOS and STM32Cube accelerate IoT development

According to IDC, the number of connected IoT devices will reach 41.6 billion by 2025 as more industry organizations realize the value of the data generated by digital devices. When most people think of IoT devices, they usually think of connected sensors or cameras used in smart home technology. These devices usually run on a basic central processing unit or other operating system. However, not all IoT devices have a true CPU, but rely on microcontrollers.

Devices run by microcontrollers are often older, such as smoke detectors, and do not have the ability to connect directly to the cloud. This partnership will help connect these basic IoT devices securely to the cloud and pave the way for more advanced applications.

Recently, Microsoft and ST recently announced a key collaboration around Azure RTOS and most of its components, which will become an important part of the STM32Cube ecosystem, a tool set and software unit used to facilitate development. Simply put, Microsoft works with ST to ensure that their operating software can effectively utilize the STM32 microcontroller, and ST's goal is to enable developers to quickly enjoy the operating system and its many middleware and stacks. STM32 will remain a platform open to all RTOS, which means that users who want to use FreeRTOS, Zephyr, Mbed or any other operating system for embedded systems can still do so. However, the results of the collaboration with Microsoft enhance ST's current solutions, provide a comprehensive set of features, and allow the team to quickly meet certain industry certifications.

RTOS will gain a foothold in the era of the Internet of Things

Compared with general operating systems, the biggest feature of RTOS is "real-time". If there is a task to be executed, the real-time operating system will execute the task immediately (in a short time) without a long delay. This feature ensures the timely execution of each task.

The concept of embedded operating system is often mentioned together with real-time operating system, but in fact these are two completely different things. Although most real-time operating systems are embedded operating systems, not all embedded operating systems are real-time.

There are some common misunderstandings about real-time operating systems, such as: fast speed, high throughput, concise code, small code size, etc. In fact, these are not the characteristics of real-time operating systems, and other operating systems can also do so.

RTOS systems are not a new concept, but they are evolving. Other names in this space include Wind River VxWorks, Blackberry QNX, and the open source Amazon FreeRTOS.

In 2019, Microsoft acquired Express Logic, a leader in RTOS for IoT and edge devices powered by microcontrollers. With this acquisition, Express Logic's ThreadX RTOS was integrated with other aspects of the Azure IoT cloud service to form Azure RTOS.

STM32Cube

ST introduced STM32Cube in 2014. It consists of software libraries and development tools, providing designers with a complete toolbox and participating in every step of project development. STM32Cube utilities and packages are free to use and have a very business-friendly license. In most cases, the libraries come with source code, so developers can not only see how we implement certain functions, but also reuse them in their applications, thus simplifying their work and reducing time to market. ST blogs often mention some cases where the STM32Cube software is used to alleviate the inherent complexity of embedded system programming, such as Connected X.0 from Nytec Inc. or Autolabs and Chris from Germany.

What is the experience like with Azure RTOS on STM32?

Azure RTOS is the only free operating system for embedded systems that offers many certifications, including safety certifications (IEC 61508 SIL 4, ISO 26262 ASIL D, IEC 62304 Medical Class C) and EAL4+, FIPS 140-2. Therefore, users looking to enter the industrial, automotive or medical markets can benefit from these standards and provide greater assurance to their customers by leveraging Microsoft's offerings in the ST Partner Program. In addition, ST will work with Microsoft to ensure that Azure RTOS leverages key IP in STM32 MCUs, such as ST's hardware encryption core. As a result, teams not only benefit from an RTOS that meets strict security standards, but also enjoy hardware optimizations that enable them to protect their systems and users more effectively.

In addition, the transition from proof of concept to final product can be a difficult task. Therefore, in order to shorten the time to market, all STM32 MCUs will receive free Azure RTOS evaluation and production licenses. Developers will be able to modify the source code and publish it. In addition, ST will also update or release new STM32Cube embedded software packages and tools to take advantage of Azure RTOS middleware and stacks.

What will Azure RTOS bring to STM32Cube?

At the core of Azure RTOS, ThreadX RTOS has powerful scheduling capabilities and other features. Microsoft explained how traditionally RTOS allows any thread with a higher priority to preempt, that is, take over the currently running thread with a lower priority. ThreadX provides more granularity, allowing developers to greatly optimize performance by setting thresholds to prevent preemption and reduce context switches. Similarly, it also provides event chaining to support specific actions when an event occurs. Therefore, threads waiting for events can be automatically started, facilitating development and reducing the resources required.

Providing Azure RTOS as one of the STM32Cube middleware means that users will be able to benefit from Azure RTOS more easily while still enjoying the best that ST development platforms have to offer. For example, Azure RTOS also comes with FileX, a file system that provides advanced features on NAND and NOR flash memories, such as fault tolerance or wear leveling. NetX and NetX Duo are network stacks that provide TCP/IP, IPv4 and IPv6, as well as many advanced protocols used in the Internet of Things, such as MQTT or COAP. There is also a USBX that facilitates the use of USB interfaces as host or device.

What hasn’t changed?

Since ST's TouchGFX framework makes embedded GUIs more accessible, ST will not use the GUIX component of Azure RTOS. Similarly, ST will continue to support, use and develop the new STM32CubeMonitor instead of using Microsoft's TraceX. Therefore, this collaboration is very beneficial for engineers and industry leaders, who can get more features without losing the tools and environments they rely on.

Further reading: Azure RTOS: popular with semiconductor manufacturers

1. Renesas

Azure RTOS (formerly known as ThreadX RTOS) is one of the most widely deployed RTOS in MCU-based devices worldwide, and many semiconductor companies have cooperated with it.

Renesas’ extensive secure embedded design experience will be combined with easy and seamless out-of-the-box support for Microsoft Azure RTOS across the Renesas microcontroller (MCU) and microprocessor (MPU) portfolio. Renesas Electronics Corporation reports that it is able to simplify the device-to-cloud experience for IoT developers. The collaboration will help deliver complete chip-to-cloud Internet of Things (IoT) solutions based on Renesas’ smart and secure devices and Microsoft Azure IoT building blocks, including Azure RTOS, Azure IoT Device SDK for C, IoT Plug and Play, IoT Central, and IoT Hub.

Currently integrated with the Renesas Synergy Software Package (SSP), this new effort extends Azure RTOS to a wider range of Renesas MCU (RA and RX) and MPU (RZ/A) product lines, starting with out-of-the-box integration into the new Renesas RA Flexible Software Package (FSP).

2.NXP

NXP Semiconductors has partnered with Microsoft to bring Microsoft’s Azure real-time operating system (RTOS) to its broader EdgeVerse processing solutions. The collaboration will allow NXP’s developer community to access Azure RTOS capabilities using MCUXpresso tools and software.

Azure RTOS support is currently available for many of NXP’s 32-bit LPC and i.MX RT crossover microcontrollers (MCUs), but according to the release, the announcement extends availability to the MCUXpresso software development kit (SDK).

NXP previously used FreeRTOS for both the RTOS and kernel, bringing in several different open source applications and partnerships for the middleware. But with Azure RTOS, users have a fully integrated middleware, tools for file management, graphical user interface, security, networking and wired connectivity.

It can be said that Azure RTOS integration will help streamline the development cycle, helping teams select the right processor, deploy secure intelligent edge devices, build local area networks and connect to the cloud - all of which will provide faster time to market for industrial Internet of Things (IoT) products.