Real-Time Operating Systems: A Primer

Introduction

Embedded system operating systems (ESOS) are small, specialized operating systems designed to run on embedded systems. Embedded systems are typically used in devices that require real-time performance, such as industrial control systems, medical devices, automotive systems, and more recently in consumer electronics such as smart speakers.

ESOS are different from traditional operating systems, such as Windows and macOS, in several ways. First, ESOS are much smaller and simpler than traditional operating systems. This is because embedded systems typically have limited memory and processing power. Second, ESOS are designed to be deterministic. This means that they can guarantee that tasks will be executed within a specified time period. This is essential for real-time applications. Another way to descripe this is the realtome os are close to the "metal" aka hardware chip itself without many layers of software abstractions. 

Types of ESOS

There are two main types of ESOS: real-time operating systems (RTOSes) and non-real-time operating systems (NRToses). RTOSes are designed to provide deterministic performance, while NRToses are not.

RTOSes are typically used in applications where timing is critical, such as industrial control systems and medical devices. NRToses are typically used in applications where timing is not critical, such as consumer electronics and home appliances.

Features of ESOS

ESOS typically have the following features:

• Real-time scheduling: ESOS must be able to schedule tasks to meet deadlines, ensuring that critical tasks are executed on time. 

• Interrupt handling: ESOS must be able to handle interrupts quickly and efficiently.

• Memory management: ESOS must be able to manage memory effectively in order to meet the limited memory constraints of embedded systems.

• Device drivers: ESOS must provide device drivers for the hardware devices that are connected to the embedded system such through common peripherals, such as serial ports, I2C, and SPI. 

Choosing an ESOS

There are many different ESOS available, so it is important to choose the right one for your application. The following factors should be considered when choosing an ESOS:

• The requirements of your application: What are the timing requirements of your application? How much memory do you have available?

• The features of the ESOS: What features are important to you? Do you need real-time scheduling? Interrupt handling? Memory management? Device drivers?

• The support for the ESOS: Is there good support for the ESOS? Is there a community of users and developers?

Popolar ESOS in consumer electronics

Zephyr is a small, scalable, portable, and a relatively new open-source RTOS for embedded systems. It is based on the Linux kernel and includes features such as real-time scheduling, interrupt handling, memory management, and device drivers. Zephyr is a good choice for applications that require a small, scalable, and portable RTOS.

Here are some of the benefits of using Zephyr RTOS:

• Open source: Zephyr is free to use and modify.

• Portable: Zephyr can be run on a wide range of hardware platforms.

• Scalable: Zephyr can be used for both small and large embedded systems.

If you are looking for a small, scalable, and portable RTOS for your embedded system, then Zephyr is a good option to consider.

Table of Summary on Popular ESOS