基于互斥量的MbedOS调度机制剖析

为了能清晰理解互斥量对共享资源的独占访问原理与机制,在简要分析实时操作系统的互斥量的含义、应用场合、调度机制以及关键要素作用的基础上,对mbedOS互斥量调度机制进行了理论剖析。以KL36芯片为例对mbedOS的互斥量进行了实践,基于时序图采用printf方法直观地输出了线程响应互斥量的调度过程信息,并对互斥量调度机制的实时性能进行分析。通过对互斥量调度机制的剖析,有助于进一步分析mbedOS的其他同步与通信方式,也可为深入理解其他实时操作系统的同步与通信手段提供参考借鉴。

The Design of I/O Subsystem in Satellite Real-Time Microkernel Operating System

One of the most important features of modern minor satellites is to realize autonomous moving. The performance of the satellite autonomous computer operating system acting as the control center is utmost important. The recent trend in operating system development is adopting microkernel architecture which holds such advantages as microminiaturization, modularity, portability and extendibility. The performance of I/O subsystem is currently receiving considerable research attention. Object-orientation offers an approach to application development in which software system can be constructed by composing and refining the pre-designed plug-compatible software components.It also starts with some basic notions fairly well accepted in computer science, namely encapsulation and reuse. In this paper, a new object-oriented real-time I/O subsystem model has been designed.In this model, the traditional I/O subsystem framework is discarded and a stream mechanism based on the object-oriented concept is introduced. In addition, the I/O requests are classified according to their time emergency to obtain real-time performance. So, this model meets such satelliteperformance requirements as reliability, flexibility, portability and real-time performance.

Digital arc welding power supply based on real-time operating system

A digital arc welding power supply was designed with the advanced reduced instruction set computer machine （ARM） and embedded real-time multi-task operating system micro C/OS- Ⅱ. The ARM, with its powerful calculating speed and complete peripheral equipments, is very suitable to work as the controller of the digital power supply. The micro C/OS- Ⅱ transplanted in ARM, helps to improve the respondent speed against various welding signals, as well as the reliability of the controlling software. The welding process consists of nine tasks. The tasks of great significance on reliability of the welder, for example, the A/D conversion of current and voltage, enjoy top priority. To avoid simultaneous-sharing on A/D converter and LCD module, two semaphores are introduced in to ensure the smooth performance of the welding power supply. Proven by experiments ,the ARM and the micro C/OS- Ⅱ can greatly improve both the respondent speed and the reliability of the digital welder.

A Smart Phone-oriented Embedded Real-time Operating System

This article presents an embedded Smart Phone Operating System (SPOS) independently designed by ZTE Corporation. The SPOS is based on single kernel architecture with its multi-task real-time kernel supporting hardware platforms and resources of mainstream mobile phones. It has remarkable advantages such as highly efficient and dynamic power management, priority - based preemptive scheduling, fast startup, a variety of drivers, and excellent system stability and operability. For the development of upper layer communication protocols and application software, the SPOS provides wireless communication interfaces and the application program framework.

mbedOS实时操作系统延时机制剖析

延时函数的使用可以避免程序空跑,让CPU更好地为其他任务服务。通过对延时函数基本原理的阐述,剖析了mbedOS实时操作系统延时函数的调度机制。以意法半导体的STM32L431芯片为例,进行mbedOS延时函数剖析实践,结合相关函数、关键代码、流程图、时序图、printf调试等分析手段,将延时函数的整个调度过程显示输出。通过对延时函数的分析,有助于读者从微观层面理解其调度过程,也可为分析其他实时操作系统提供参考和借鉴。

Low-Power Operational Amplifier for Real-Time Signal Processing System of Micro Air Vehicle

A low-power complementary metal oxide semiconductor（CMOS） operational amplifier （op-amp） for real-time signal processing of micro air vehicle （MAV） is designed in this paper.Traditional folded cascode architecture with positive channel metal oxide semiconductor（PMOS） differential input transistors and sub-threshold technology are applied under the low supply voltage.Simulation results show that this amplifier has significantly low power,while maintaining almost the same gain,bandwidth and other key performances.The power required is only 0.12 mW,which is applicable to low-power and low-voltage real-time signal acquisition and processing system.

Real-Time Operation of Microgrids

Microgrid (MG) systems effectively integrate a generation mix of solar, wind, and other renewable energy resources. The intermittent nature of renewable resources and the unpredictable weather conditions contribute largely to the unreliability of microgrid real-time operation. This paper investigates the behavior of microgrid for different intermittent scenarios of photovoltaic generation in real-time. Reactive power coordination control and load shedding mechanisms are used for reliable operation and are implemented using OPAL-RT simulator integrated with Matlab. In an islanded MG, load shedding can be an effective mechanism to maintain generation-load balance. The microgrid of the German Jordanian University (GJU) is used for illustration. The results show that reactive power coordination control not only stabilizes the MG operation in real-time but also reduces power losses on transmission lines. The results also show that the power losses at some substations are reduced by a range of 6% - 9.8%.

实时操作系统mbedOS的移植方法

MbedOS是ARM公司于2014年开始推出的一款面向智能终端与物联网节点的实时操作系统,主要用于对响应时间有较高实时性要求的嵌入式系统.在深入分析mbedOS的基本功能、调度机制、延时函数机制、任务间通信机制等基础上,以可移植的mbedOS工程框架为基础,分析移植的共性问题,给出具体的移植方法.在此基础上,实现了mbedOS在ARM Cortex-M系列的不同内核及不同MCU上的移植,还给出了不同开发环境间移植共性问题分析,为mbedOS的应用研究提供了基础,有效地降低了mbedOS的移植难度,也可为其他RTOS的移植提供参考.

基于ARM Cortex-M4的mbedOS调度机制剖析

为了能清晰理解mbedOS调度基本原理与机制,通过阐述ARM(Advanced RISC Machines)Cortex-M4内核对实时操作系统的支持特性,分析了实时操作系统常用的调度策略,采用流程图分析、上下文核心代码解析等方法重点剖析了SVC(Supervisor Call)中断、PendSV中断和SysTick中断3种mbedOS调度策略实现方法,最后以意法半导体的STM32L431芯片为例给出了mbedOS的线程调度剖析实践。通过对mbedOS的线程调度剖析,有助于深入理解mbedOS的调度机理,为设计多任务系统提供帮助,也为分析其他实时操作系统提供参考借鉴。

A Concept of Dynamically Reconfigurable Real-time Vision System for Autonomous Mobile Robotics

This paper describes specific constraints of vision systems that are dedicated to be embedded in mobile robots. If PC-based hardware architecture is convenient in this field because of its versatility, flexibility, performance, and cost, current real-time operating systems are not completely adapted to long processing with varying duration, and it is often necessary to oversize the system to guarantee fail-safe functioning. Also, interactions with other robotic tasks having more priority are difficult to handle. To answer this problem, we have developed a dynamically reconfigurable vision processing system, based on the innovative features of Cleopatre real-time applicative layer concerning scheduling and fault tolerance. This framework allows to define emergency and optional tasks to ensure a minimal quality of service for the other subsystems of the robot, while allowing to adapt dynamically vision processing chain to an exceptional overlasting vision process or processor overload. Thus, it allows a better cohabitation of several subsystems in a single hardware, and to develop less expensive but safe systems, as they will be designed for the regular case and not rare exceptional ones. Finally, it brings a new way to think and develop vision systems, with pairs of complementary operators.

实时操作系统mbedOS互斥量调度机制剖析

嵌入式产品研发中使用多线程并发运行时,为避免公共资源被破坏或线程运行异常,通常使用互斥量(Mutex)来防止公共资源在线程运行时被其他线程抢占。不同于使用单一变量实现的互斥量,在实时操作系统中为优化线程调度并避免错误,所使用的互斥量较复杂且不易理解。目前关于嵌入式实时操作系统中互斥量的实现及应用的相关资料较少,文中在对实时操作系统mbedOS中互斥量的数据结构与操作函数进行详细分析的基础上,设计出一个使用互斥量保护公共资源的软件实例,实例中包含对小灯的控制以及使用串口输出线程的实时运行情况。通过观察灯光的变化并结合串口输出信息,能够直观地理解mbedOS对使用互斥量的进程调度机制,也可为读者理解其他实时操作系统中互斥量的机制提供参考。

基于GEC架构的mbedOS驻留技术研究

针对当前MCU在实时操作系统上进行嵌入式应用程序开发的需求,提出使用GEC架构,并且在该架构下实现mbedOS操作系统驻留内存,其中提出合理划分Flash和RAM空间设计规则,总结出使用API动态链接技术实现用户程序调用接口程序进行编程,实现嵌入式编程和通用计算机编程类似,缩短编译时间,加快开发效率.最后分别在S32K144和MKL36Z64进行设计实验,实验表明该技术具有可行性.

Analysis and Comparison of Five Kinds of Typical Device-Level Embedded Operating Systems

Today, the number of embedded system was applied in the field of automation and control has far exceeded a variety of general-purpose computer. Embedded system is gradually penetrated into all fields of human society, and ubiquitous embedded applications constitute the 'ubiquitous' computing era. Embedded operating system is the core of the em-bedded system, and it directly affects the performance of the whole system. Our Liaoning Provincial Key Laboratory of Embedded Technology has successfully developed five kinds of device-level embedded operating systems by more than ten years’ efforts, and these systems are Webit 5.0, Worix, μKernel, iDCX 128 and μc/os-II 128. This paper mainly analyses and compares the implementation mechanism and performance of these five kinds of device-level embedded operating systems in detail.

MODEL-BASED DEVELOPMENT OF REAL-TIME SOFTWARE SYSTEM FOR ELECTRONIC UNIT PUMP SYSTEM

A real-time operating system （RTOS）, also named OS, is designed based on the hardware platform of MC68376, and is implemented in the electronic control system for unit pump in diesel engine. A parallel and time-based task division method is introduced and the multi-task software architecture is built in the software system for electronic unit pump （EUP） system. The V-model software development process is used to control algorithm of each task. The simulation results of the hardware-in-the-loop simulation system （HILSS） and the engine experimental results show that the OS is an efficient real-time kernel, and can meet the real-time demands of EUP system; The built multi-task software system is real-time, determinate and reliable. V-model development is a good development process of control algorithms for EUP system, the control precision of control system can be ensured, and the development cycle and cost are also decreased.

DEVELOPMENT OF AN AIRBORNE SAR REAL-TIME DIGITAL IMAGING PROCESSOR

An airborne SAR real-time digital imaging processor is presented, and its realtime digital imaging principle and main technical parameters are analyzed briefly. The system configuration and logical structure are described in detail. Finally the main features of this system and examples of imagery obtained with the system are also presented.

High performance reconfigurable hardware system for real-time image processing

A novel reconfigurable hardware system which uses both muhi-DSP and FPGA to attain high performance and real-time image processing are presented. The system structure and working principle of mainly processing multi-BSP board, extended multi-DSP board are analysed. The outstanding advantage is that the communication among different board components of this system is supported by high speed link ports ＆ serial ports for increasing the system performance and computational power. Then the implementation of embedded real-time operating systems （RTOS） by us is discussed in detail. In this system, we adopt two kinds of parallel structures controlled by RTOS for parallel processing of algorithms. The experimental results show that exploitive period of the system is short, and maintenance convenient. Thus it is suitable for real-time image processing and can get satisfactory effect of image recognition.

Influences of Network Delay on Quality of Experience for Soft Objects in Networked Real-Time Game with Haptic Sense

In this paper, we investigate the influences of network delay on QoE (Quality of Experience) such as the operability of haptic interface device and the fairness between players for soft objects in a networked real-time game subjectively and objectively. We handle a networked balloon bursting game in which two players burst balloons (i.e., soft objects) in a 3D virtual space by using haptic interface devices, and the players compete for the number of burst balloons. As a result, we find that the operability depends on the network delay from the local terminal to the other terminal, and the fairness is mainly dependent on the difference in network delay between the players’ terminals. We confirm that there exists a trade-off relationship between the operability and the fairness. We also see that the contribution of the fairness is larger than that of the operability to the comprehensive quality (i.e., the weighted sum of the operability and fairness). Assessment results further show that the output timing of terminals should be adjusted to the terminal which has the latest output timing to maintain the fairness when the difference in network delay between the terminals is large. In this way, the comprehensive quality at each terminal can be maintained as high as possible.

Architecture of the Graphics System for Embedded Real-Time Operating Systems

This paper presents a new architecture of a graphics system for microkernel operating systems,including real-time operating systems.The following major parts of the architecture are presented:a user-level subsystem responsible for interaction with user applications;a bottom-level subsystem providing the functionality for graphics drivers,such as managing graphics output,video memory management,etc.;a kernel-level subsystem providing interaction with the kernel,and performing low-level operations,such as working with physical memory,processes,etc.The mechanisms of interaction of user applications with the user level of the graphics system,as well as interaction of the different levels of the graphics subsystem are presented.The paper pays much attention to various approaches to testing:the use of unit testing,testing using hardware and software emulators.Another important characteristic of a graphics system is its performance,in particular the performance of low-level operations such as memory allocation:the developed architecture suggests using a separate memory allocator which is faster than standard memory allocation functions.Comparison of the performances of graphics system implementation for microkernel real-time operating system and graphics server Xorg is presented,showing significant superiority of the proposed architecture in a number of work scenarios.

Architecture of Graphics System with 3D Acceleration Support for Embedded Operating Systems

An increasing number of tasks now require the use of hardware accelerators to reduce the time required for computation and display the computational results.This paper presents a new graphics system architecture for operating systems(OSs)with microkernel architecture,including real-time OSs.The proposed system architecture provides capabilities for displaying graphical images on various information display devices and for accelerating graphical operations on GPU.The architecture of the graphics system uses a concept of allocators to manage system and video memory,provides an abstraction of memory operations with a single interface for video memory management,and simplifies memory handling where incorrect operation is the cause of many failures.A comparison between the performance of a real-time OS and Linux OS implementing the graphics system using the example of a glmark2 benchmark is presented,thereby the superiority of the proposed architecture in several scenarios is demonstrated.

Evolution analysis of a UAV real-time operating system from a network perspective

With the flourishing development of Unmanned Aerial Vehicles(UAVs), the mission tasks of UAVs have become more and more complex. Consequently, a Real-Time Operating System(RTOS) that provides operating environments for various mission services on these UAVs has become crucial, which leads to the necessity of having a deep understanding of an RTOS. In this paper, an empirical study is conducted on FreeRTOS, a commonly used RTOS for UAVs, from a complex network perspective. A total of 85 releases of FreeRTOS, from V2.4.2 to V10.0.0, are modeled as directed networks, in which the nodes represent functions and the edges denote function calls. It is found that the size of the FreeRTOS network has grown almost linearly with the evolution of the versions, while its main core has evolved steadily. In addition, a k-core analysis-based metric is proposed to identify major functionality changes of FreeRTOS during its evolution.The result shows that the identified versions are consistent with the version change logs. Finally,it is found that the clustering coefficient of the Linux OS scheduler is larger than that of the FreeRTOS scheduler. In conclusion, the empirical results provide useful guidance for developers and users of UAV RTOSs.