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- 点击数：1425
Synopsis:
A novel design is presented to defend against electromagnetic interference (EMI) in a high speed data acquisition system. Problems that affect signal integrity (SI) in high speed image acquisition systems, such as reflection, crosstalk and ground bounce, are deeply analyzed in a manner consistent with transmission line theory. The results can theoretically inform EMI design of important networks, including system power, ground, clocks, high speed wires and decoupling capacitors. Experiments simulating print circuit board(PCB) reflection and EMI on high speed signal wires between DM642 and SDRAM are conducted. The power and ground should be placed separately in different layers. The clock lines passing through holes should be as few as possible. The signal lines should be as close to the same length as possible. The results show that amplitude of the signal overshoot is less than 0.7 V and the EMI amplitude is within the federal communications commission(FCC) standard.
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2018-11-23
767.55 KB
503摘要：
针对高速数据采集电路中的电磁干扰问题,提出一种有效的抗干扰设计方案。利用信号传输线理论,对高速图像采集系统中影响信号完整性的反射、串扰和地弹等问题进行了理论分析,对系统电源、地、时钟、高速信号线等重点网络的电磁干扰设计进行理论指导和设计,并且对DM642与SDRAM间的高速信号线进行PCB(print circuit board)的反射、电磁干扰等仿真分析。设计中电源和地独立分层布线,尽量减少时钟线过孔,信号布线尽量等长。结果显示系统信号传输的过冲幅度小于0.7V,电磁干扰强度在FCC标准控制范围之内。
- 说明
- 点击数：1368
摘要：
在构建CPU（Central Process Unit ，CPU）与GPU（Graphic Process Unit）或者CPU与其它设备协同计算的过程中，通过PCI（Peripheral Component Interconnect）总线将GPU等其他设备连接至CPU ，承担并行计算的任务。为了解决PCI接口芯片与GPU芯片之间的异步传输和时序匹配问题，基于 PCI总线规范与GPU 芯片的时序规范，采用跨时钟域信号的处理方法，设计了一个CPU与GPU 之间跨时钟域连接的时序匹配接口电路。通过仿真，验证了该电路的正确性。结果表明，该电路可工作在252 M Hz频率下，能够满足GPU 与CPU 间接口电路对速率和带宽的要求。
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CPU与GPU之间接口电路的设计与实现
- 说明
- 点击数：2091
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基于UEFI的Application和Driver的分析与开发
摘要：
UEFI(Unified Extensible Firmware Interface,统一的可扩展固件接口)是由Intel提出的下一代BIOS构架.基于UEFI2.0规范,借助UEFI开发环境:Intel的 EDK(EFI Develop Kit),对UEFI Application和UEFI Driver作了一定的分析,并通过两个例子分别予以实现.
- 说明
- 点击数：1811
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基于UEFI的可信BIOS研究与实现
摘要：
分析固件基本输入输出系统（BIOS）的安全需求,定义了可信BIOS概念。基于UEFI规 范和可信计算机制设计UTBIOS体系结构。UTBIOS的实现以新一代符合UEFI规范的BIOS产品为基础,使用可信测量根核对BIOS运行和系统引 导过程中各部件进行可信测量,构建操作系统运行前的可信链,讨论可信测量对BIOS引导过程的性能影响。
- 说明
- 点击数：2087
摘要：
统一可扩展固件接口（UEFI）缺乏相应的安全保障机制，易受恶意代码的攻击，而传统的计算机安全系统无法为固件启动过程和操作系统引导过程提供安全保护。针对上述问题，设计基于UEFI的恶意代码防范系统。该系统利用多模式匹配算法实现特征码检测引擎，用于在计算机启动过程中检测与清除恶意代码，并提供恶意启动项处理及系统内核文件备份等功能。实验结果证明，该系统能为固件及上层操作系统提供完善的安全保护，且代码尺寸小、检测速度快，恶意代码识别率高。
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基于UEFI固件的恶意代码防范技术研究
Synopsis:
Unified Extensible Firmware Interface(UEFI) faces a grim challenges of malicious code attack. The traditional computer security software can not provide security for the firmware and operating system boot process. In order to solve the problem, this paper designs a malicious code defense system based on UEFI firmware. By using the multi-pattern matching algorithm, a signature detecting engine under UEFI environment is implemented, which provides functionally of malicious code detect, boot option analysis and firmware and operating system kernel backup. Experimental results prove that the system can effectively resist malicious code with small code size and low costs to meet the firmware’s need of flash size and fast boot.
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