Wearable devices represent just one area of the Internet of Things (IoT). Health- and fitness-oriented wearable devices tend to dominate this arena, but a range of form factors and devices provide everything from biometric measurements such as heart rate and perspiration levels to security information (Fig. 1). A number of these devices have displays that allow them to operate in a standalone fashion, and most have some type of wireless-communication support.
It’s possible to have a dedicated application run on bare metal. Though many of these compact devices use a microcontroller to provide low-power operation, having an operating system can make programming easier. It often helps improve performance, safety, and security, since the services provided by the operating system have been examined and optimized for a wider range of environments rather than a single application.
A plethora of operating systems (OSs) and real-time operating systems (RTOSs) are vying for developers’ eyes when it comes to this space, including a large number of commercial and open-source alternative—even when IoT is brought into the mix. The discussion these days goes beyond just connectivity (e.g., a wireless stack), and now includes the IoT communication stack that’s a superset. Features like security and over-the-air updates need to be integrated with the OS. That’s a lot of software to pack into a small space.
Linux sometimes plays in this field, but it includes a number of more compact operating systems such as ARM mbed, FreeRTOS, NuttX, RIOT OS, TinyOS, and Zephyr.