Shulou(Shulou.com)06/03 Report--

Nowadays, embedded applications are everywhere, whether consumer electronics, communication terminals, system equipment, industrial control, automotive electronic systems or aerospace. Embedded has come into our life, in other words, our life will be inseparable from embedded, the future development prospect is very considerable. Now, billions of microprocessors are produced every year, most of which are widely used in all kinds of embedded systems.

At present, in terms of embedded system hardware platform, all kinds of microcontrollers and digital signal processors (DSP) products can carefully select the hardware core platform with the most comprehensive advantages, no matter from the brand, functional characteristics, or according to the specific requirements of the target application, such as cost, processing capacity, power requirements, integration, development cycle, technical difficulty and so on. In terms of embedded operating system, whether it is a variety of commercial or free versions of the open source Linux camp, or "heavyweight" platforms such as WinCE, vxWorks, or Windows Mobile, Symbian, Android, etc., optimized for specific applications, you can also easily choose the best operating system software platform.

The design process of embedded system is actually a process of co-development of hardware and software. In the evaluation of hardware and software platform selection, simply leaving the hardware to evaluate the operating system or the operating system to evaluate the hardware platform is biased, especially for many non-general-purpose processors. At present, many embedded hardware platforms provide operating systems and software module resources optimized for target applications, and some commercial operating systems are also optimized for mainstream hardware platforms. and provide a large number of third-party optimized operating system versions. These resources are of great significance for embedded system design. For this reason, this paper introduces a unique embedded platform core processor, that is, converged processor Blackfin and its mainstream supporting operating system and related resources application and design methods. Those who have problems or practical information here can be private, and have saved a lot of practical information in recent years. First, the centralized design scheme of embedded digital photo frame is briefly introduced.

1 selection of hardware processor Blackfin

This design chooses convergent processor Blackfin to build a unique embedded hardware platform. Convergent processor Blackfin is a MSA jointly developed by ADI and Intel. It integrates 32-bit RISC instruction set, double 16-bit multiplicative accumulation (MAC) signal processing functions and the ease of use of general-purpose microcontrollers. This combination of convergent processing capabilities enables Blackfin processors to play an excellent role in flag processing and control applications. It also eliminates the need for separate heterogeneous processors in many applications, thus greatly simplifying hardware and software design. Blackfin processor is very suitable for embedded audio, video and communication applications with convergence as the key technology, including multi-format audio, video, language and image processing, multi-mode baseband and packet processing, control processing and real-time security processing. It is the design flexibility and scalability of this unique system architecture that has won a wide range of adaptability for Blackfin processors, and also makes it widely used in digital home entertainment, network and streaming media, automobile remote information processing and information entertainment, digital radio and mobile TV terminals.

Blackfin processors provide performance up to 756MHz and low power voltages as low as 0.8V in single-core products. All Blackfin processors have multiple independent DMA controllers that support automatic data transfer and require very little processor core overhead. In addition, the Blackfin processor also has rich memory configuration, which can greatly facilitate the application development of embedded systems. ADSP-BF51x series processors have NOR flash memory, NAND flash memory, ferroelectric storage (FRAM) and SDRAM at the same time, and also provide disposable programmable memory that supports Lockbox security technology.

The Blackfin processor architecture is fully compliant with SIMD standards and comes with instructions to accelerate video and image processing. This architecture is very suitable for full signal processing / analysis applications. Because Blackfin processors have the best code density and require little or no code optimization, they do not encounter the performance space obstacles common to other traditional processors.

2 selection of uCLinux operating system

For a new embedded development project, the choice of embedded operating system is as important as the choice of embedded hardware microprocessor. For Blackfin processors, in addition to the unique performance advantages of the processor itself, powerful embedded operating system resources are also a key factor in embedded system design. Blackfin processors support operating systems such as VisualDSP's own operating system kernel (VDK), ThreadX, uCLinux and Nucleas, which avoids the extended end product development cycle due to operating system changes when porting the operating system from other processor platforms to the Blackfin platform. Various operating systems have different special × ×, as well as different prices, copyright fees and other terms. From the point of view of characteristics, the embedded operating system includes the operating system VDK with compact code and low complexity, the complex and rich operating system uClinux, the INTEGRI TY with high reliability and the RTA-OSEK focusing on the needs of the automobile market. Through the analysis of the functions of various operating systems, this design finally chooses the uCLinux operating system to design the digital photo frame. Figure 1 shows the organizational structure of its operating system on Blackfin.

Linux is a widely used embedded operating system. In all the mainstream embedded systems, the Linux operating system has become an important force in embedded applications, regardless of its super network function, arbitrary tailoring, completely free and universal Linux API characteristics, as well as extensive open resources. UClinux is a Linux system for microprocessor applications, and the source code is completely open. at the same time, according to the characteristics of embedded applications, uClinux modifies and recompiles the kernel of Linux, so the kernel is smaller. UClinux also contains the API commonly used by Linux, and retains the high stability, powerful network features and excellent file system support features of the original Linux operating system.

The uClinux operating system can run directly on the Blackfin processor. For many embedded applications, few of the solutions at the same price as Blackfin processors can support Linu x. In fact, Linux still has many challenges when facing specific embedded applications, such as applications with limited memory space or high security applications that require real-time certainty. One of the main features of this design is that the Blackfin processor of ADI company has integrated a large number of hardware drivers and application routines in uClinux, including wireless LAN drivers, audio / video programming × × drivers and so on. These drivers can help customers easily transplant applications from the original system to the Blackfin platform. In addition, ADI and Arcturus Networ ks also jointly launched a new uCBF54x startup development tool kit and system module. The software provided by the development kit includes open source uCliunx BSP (board-level support package) and Arcturus voice and management middleware, as well as complete SIP and RTP stacks. Therefore, Blackfin Linux has become one of the most stable embedded Linux distributions in the field of embedded systems.

3 software development tool environment

As the application of embedded system products is becoming more and more complex and the time for products to be put on the market is becoming more and more urgent, a perfect development environment is becoming more and more important. In addition to a full range of optimized embedded operating systems, having a complete development environment is also one of the important factors in the development of embedded systems. For this reason, ADI also provides ADI CROSSCO RE software and hardware tools that can support other Blackfin processors, including VisualDSP++ integrated development and debugging environment, simulator, and EZ-KIT Lite evaluation hardware.

In addition, ADI also provides a large number of system service programs for embedded system development, such as software libraries that provide a variety of common functions for embedded systems. These service programs are actually utility programs that can be used in any system. They can not only run in an independent environment without RTOS, but also can be used in VDK environment. Using these system service programs, we can easily and efficiently access the hardware subsystem of Blackfin processor, including phase-locked loop, direct memory access, interrupt controller, flag controller and timer. All Blackfin processors can use a common set of AM, and various applications and device drivers can also use these system service ordering. The software contained in these system service programs has been repeatedly tested, and the performance is stable and reliable, and these programs can be used directly in design. In addition, using these services, you can easily integrate these modular software. in fact, these services are provided with the VisualDSP++ integrated development environment. I hope these will help you. If you want to develop in the embedded system but have no direction, you can also communicate with each other and make progress together.

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