A brief discussion on embedded real-time systems and their applications in communication systems

Among the many branches of the IT industry, embedded is one of the fastest growing areas, because more and more products and services require the support of embedded systems. Many industries such as consumer electronics, manufacturing, office automation, industrial control, etc. are closely related to embedded.

As a new, application-oriented computer system, embedded systems not only integrate the common features of general-purpose computer systems, but also include many new technologies suitable for "embedded" applications. Because they are technically different from general-purpose computer systems, this article first introduces the basic concepts of embedded systems and their key technologies, and explains their technical characteristics and applicability in combination with their applications in communication systems.

1 Embedded Real-Time Systems

The embedded system includes one or more control CPUs and high-level software developed for a specific application environment, usually including an operating system. During use, the behavior of the CPU and software inside the system is not perceived by the outside world, so it is called an "embedded" system; embedded systems with a very short response time to external events are usually called "embedded real-time systems"; operating systems used in embedded real-time systems are called "embedded real-time operating systems."

1.1 Composition of Embedded Real-Time Systems

Embedded real-time systems include hardware and software, and consist of three parts: hardware platform, embedded real-time operating system and other system software modules, and real-time application programs, as shown in Figure 1.

1.1.1 Hardware Platform

The hardware platform of an embedded real-time system usually takes a compact and highly specialized CPU as the core and combines a small number of peripheral devices with application relevance, that is, diversity.

1.1.2 Embedded real-time operating system and other system software modules

The operating system and other system software are between the hardware and the application, responsible for scheduling and managing real-time applications and completing the control and operation of the hardware.

1.1.3 Real-time Applications

Real-time applications are applications that are based on embedded real-time operating systems and use the real-time mechanisms provided by the operating system to complete specific functions of specific embedded real-time systems.

1.2 Characteristics of Embedded Real-Time Operating Systems

In addition to the common characteristics of operating systems, in order to adapt to "embedded real-time" applications, embedded real-time operating systems also have outstanding features such as real-time performance, micro-kernel combined with expansion modules to achieve universality and configurability, and the operating system does not make assumptions about peripherals.

1.2.1 Real-time

Real-time means "timely", which is a relative concept; real-time performance indicates the operating system's ability to respond to and process external events within a foreseeable time, and is one of the key indicators of embedded real-time operating system performance. Embedded real-time operating systems generally use a multi-tasking mechanism to execute applications in a concurrent manner.

1.2.2 Microkernel combined with extension modules to achieve universality and configurability

In order to adapt to different "embedded" applications in terms of structure and function, embedded real-time operating systems usually adopt an architecture that combines a microkernel with configurable functional modules, making the operation both universal and configurable. The structure of an embedded real-time operating system is shown in Figure 2.

1.2.3 The operating system does not make assumptions about peripherals

The implementation of the operating system is only related to the CPU, and does not assume other physical hardware outside the CPU. Hardware-related functions rely on another software layer called the Board Support Package to complete, thus achieving the "hardware independence" of the operating system and improving the versatility and portability of the system.

1.3 Comparison between Embedded Real-Time Systems and General-Purpose Computer Systems

By comparing Table 1, we can see that embedded systems are application-centric, computer-based, software and hardware-customizable, and adaptable to application systems. They have strict requirements on functions, reliability, cost, size, and power consumption. They are dedicated computer systems.

Table 1 Comparison between embedded real-time systems and general-purpose computer systems

2 Implementation of Embedded Real-Time System

2.1 Selecting a suitable embedded real-time operating system

Embedded real-time operating system is the core of implementing embedded real-time system. The performance of operating system directly affects the real-time performance of the whole system to a large extent. Therefore, choosing a suitable embedded real-time operating system is crucial to realize a high-performance embedded system.

2.2 Carefully divide the tasks within the application

As another important software layer, the division of tasks within the application also affects the overall performance of the embedded real-time system. In order to take into account the concurrency and overall throughput of the embedded real-time system, the division of tasks should follow the following principles:

Functionally independent operations should be a single task;

Operations with close functional connections (close coupling) should be grouped into the same task;

Functions with slow I/O operations should be divided into separate tasks;

Different priority operations are divided into different tasks;

· Operations that are computationally intensive should be divided into a separate task.

2.3 Debugging of Embedded Real-Time Systems

Unlike the design of general computer systems, the design of embedded real-time systems always involves hardware factors, so debugging the hardware platform is a necessary step. In terms of software, since embedded real-time systems are usually multi-tasking systems with strong dynamics, the functional behavior of the system needs to be determined through debugging.

3 Application of embedded real-time systems in communication systems

As a special type of computer system, the application scope of embedded real-time system has expanded to many fields, especially in the field of communication, which has achieved unprecedented development. With the opening of new network services and the increase of new equipment, telecommunication network management has become an increasingly prominent issue and has attracted much attention.

The expansion of communication networks, the massive increase in new services and new equipment require network management to have not only rich management functions, but also good management performance and efficiency; that is, network management must meet certain real-time requirements. In short, modern network management has the following two outstanding characteristics:

·Complete management functions;

Good management performance.

In order to achieve complete and efficient network management, communication equipment must enhance its own performance, thus providing a high-performance software and hardware platform for high-level network management. A new development trend has emerged in the design of communication systems, as shown in Figure 3.

The main reasons for this trend are:

(1) The previous method of using microcontrollers as a platform and running applications directly on the CPU has obvious shortcomings:

Limited hardware capabilities, unable to perform efficient and complex device management;

The hardware platform is simple and cannot effectively support multi-functional and complex network management;

The software lacks support from the operating system, and the network application design is complex, making it difficult to achieve full-featured performance network management.

(2) General-purpose computers are not suitable for this application environment due to limitations in size, cost, and efficiency.

(3) Using embedded real-time systems is an ideal solution:

Embedded real-time systems use compact and efficient CPUs in hardware, which are suitable for being "embedded" inside devices as the hardware core of control and can support complex device management;

In terms of software, the embedded real-time system is based on a high-performance embedded real-time operating system, which not only provides good real-time guarantee for the system, but also simplifies the design of high-level application programs.

As a new field of computer application, embedded real-time system has attracted more and more attention due to its simplicity and high efficiency. As the application environment becomes more and more complex, the system requires more and more functions, and embedded real-time operating system has become an essential part of realizing embedded real-time system.

After rapid development in recent years, the application scope of embedded real-time systems has expanded to areas that were previously only available for general-purpose computer systems, and the number of applications has exceeded that of general-purpose computer systems, especially in the telecommunications and IT fields, where they have been used more widely than ever before.

The rapid rise of embedded real-time systems marks the arrival of the "Post-PC Era". Embedded systems are becoming the systems with the most development potential and application prospects after PCs. Their rapid development is becoming a new and powerful driving force for the rapid development of industries such as IT (including communications and information).