UNCC ECGR 6185 - An Embedded System with uClinux based on FPGA

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An Embedded System with uClinux based on FPGA Zongqing Lu1 , Xiong Zhang2 ,Chuiliang Sun3 1School of Electronic Science and Engineering, Southeast University, Nanjing, JiangSu, 210096, China 2 School of Electronic Science and Engineering, Southeast University, Nanjing, JiangSu, 210096, China 3School of Electronic Science and Engineering, Southeast University, Nanjing, JiangSu, 210096, China [email protected], [email protected], [email protected] Abstract Nowadays Field Programmable Gate Arrays (FPGAs) have become so affordable that they can be used to replace ASICs in some fields such as embedded systems in consumer electronic industry. In the paper, we design an embedded system with uClinux OS (operating system) based on FPGA. The way and experiences of the co-design of HW/SW are presented. The paper also gives an application of MPEG2-player on the embedded system and the comparison with other embedded system based ASICs. 1. Introduction Embedded systems, which are widely used in consumer electronic appliances, are characterized by a rapidly increasing complexity and shorter product cycles. The designers are under more and more pressure to reduce design cycles usually in the presence of continuously changing specifications. This explosive growth in the embedded systems market has been fueled by rapid prototyping technologies. The ability to quickly program microprocessor memories in-circuit and reconfigure field-programmable digital hardware is critical to embedded systems engineers who must meet ever shortening development cycles [1]. FPGAs have become more and more popular for implementation of logic circuits. The flexibility of FPGAs has made them suitable for implementation of embedded SOPC systems, where a complete system fits on a single programmable chip. A processor unit in such a system is usually a soft-core processor. A soft-core processor is a microprocessor fully described in software, usually in an HDL, which can be synthesized in programmable hardware, such as FPGAs. Soft-core processors implemented in FPGAs can be easily customized to the needs of a specific target application. The two major FPGA manufacturers provide commercial soft-core processors. Xilinx offers its MicroBlaze processor [2], while Altera Nios II processors [3]. In this paper, we design the embedded system based on the Nios II soft-core processors. This paper is organized into 4 sections. In section 1, a brief description of embedded system based on FPGAs is introduced. The hardware architecture, the selecting of hardware platform and the design of hardware of embedded system on FPGAs are presented in detail in section 2. In section 3, uClinux OS and the porting of it are introduced, then the paper gives some important user applications under uClinux for consumer electronic, furthermore the design of mpeg2-player by co-design of hardware and software is brought up, which use libmpeg2[4] and libsdl[5]. In the final section, this paper focuses on the comparison between the embedded systems based on ASICs and FPGAs and analyzes the important characteristics of them. 2. Hardware system 2.1. Hardware architecture of system In the paper, we use SOPC builder provided by Altera to design the hardware system, which provides designer Nios II soft-core processor and some peripherals and allows designer to customize peripherals. This makes designer have more freedom to extend the peripherals of the embedded systems, however the designer must give HDL design of interface between the avalon bus and peripherals. Fig.1 gives our design of hardware of embedded system. In our design, we designed the Ethernet controller, SD card controller, Audio controller, LCD controller, USB controller to extend peripherals, which can make our embedded system have more functions and more available to be supported by operating system. 2008 IEEE Pacific-Asia Workshop on Computational Intelligence and Industrial Application978-0-7695-3490-9/08 $25.00 © 2008 IEEEDOI 10.1109/PACIIA.2008.856912008 IEEE Pacific-Asia Workshop on Computational Intelligence and Industrial Application978-0-7695-3490-9/08 $25.00 © 2008 IEEEDOI 10.1109/PACIIA.2008.856912008 IEEE Pacific-Asia Workshop on Computational Intelligence and Industrial Application978-0-7695-3490-9/08 $25.00 © 2008 IEEEDOI 10.1109/PACIIA.2008.85691Authorized licensed use limited to: University of North Carolina at Charlotte. Downloaded on January 27, 2010 at 10:43 from IEEE Xplore. Restrictions apply.Fig.1 Block diagram of hardware architecture 2.2. Hardware platform Our design system is based on Altera DE2-70 development board and TRDB_LCM LCD. The core of the board is Cyclone II EP2C70 FPGA, which has 68416 LEs (logic elements) and 250 M4K RAM blocks (1152000bits). The DE2-70 board includes peripheral interfaces, by integrating control chips as follows: ◆ Flash (with 8M S29GL064) ◆ SDRAM (with 32M IS42S16160B) ◆ Ethernet (with DMA9000A) ◆ USB host / client (with ISP1362) ◆ Audio (with WM8731) ◆ VGA (with ADV7123) ◆ SD card socket ◆ RS232 ◆ IrDA ◆ PS/2 The photo of DE2-70 board and TRDB_LCM LCD is shown in Fig. 2. Fig.2 Hardware platform of embedded system 2.3. Hardware design In the paper, we design the hardware by the quartus II and SOPC builder. The clock rate of the soft-core-processor based on CYCLONE II EP2C70 is up to 112MHZ, so the performance of soft-core-processor can be up to 112DMIPS(Million Instructions Per Second). A part of design of hardware in SOPC builder is shown in Fig.3. Fig.3 Design of hardware of FPGA 3. Software system design 3.1. Embedded operating system FPGA processor cores are now supported by a number of embedded operating systems. By incorporating an operating system into our design, we can easily enhance the performance of the embedded system and extend a lot of functions and easily use an efficient approach to mange all the peripherals of the embedded system. In our design, we incorporate uClinux into our embedded system, which does not require a memory management unit (MMU). It has such features as open source, stability, powerful network function and excellent file system [6]. The newest edition of uClinux for Nios II is included in nios2-linux-20080619.tar [7] which uses Linux kernel 2.6.26 and can be downloaded from the website (ftp://ftp.altera.com/outgoing/nios2-linux-20080619.tar). uClinux is a derivative of Linux, which is designed specially for microprocessor without


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UNCC ECGR 6185 - An Embedded System with uClinux based on FPGA

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