To do this for some friends to help, you can look at the reference

华为 Quidway 系列多协议路由器，支持 PPP、FR、X25、SLIP、HDLC 等网络协议，用户可通过各种广域网线路接入 Internet 及互联互访。 路由器内置安全防火墙、NAT、RADIUS 安全认证，以及 CALL BACK 等多项互联安全防护功能；并通过 CA 认证协议的验证和 IPSec 隧道协议，在 Internet 上构建安全可靠的网络通道，基于硬件的数据加密，将保密数据加密后在隧道上传输，加密数据有可靠的保密性但牺牲了效率；非保密数据可以通过一般性安全处理在隧道上传输，保证较高的转发速率。硬件加密的算法采用专门的芯片（经过国家相关部门批准）进行加密，密钥长度大于 128 位，并提供高强度的一次一密功能。配合完全自主知识产权的软硬件平台，提供网络的安全互联和数据的安全传输的安全解决方案。 而 "备份中心"的可靠性备份解决方案，实现多种线路之间的任意备份和业务分担，为网络提供业界最坚固的保护屏障，保证网络的可靠运行。-Huawei Quidway series of multi-protocol routers to support PPP, FR, X25, SLIP, HDLC and other network protocols, users can through various WAN lines and Internet access to the Internet visits. Built-in security firewall router, NAT, RADIUS authentication, and a number of other CALL BACK Internet security protection functions; And through CA and validation of the agreement IPSec agreement on the Internet to establish a secure and reliable network access, hardware-based data encryption, data encryption confidentiality the tunnels on the Tunnel, a reliable data encryptio

Here is a simple circuit for monitoring the fuel level in vehicles. It gives an audiovisual indication when the fuel level drops alarmingly below the reserve level, helping you to avoid running out of petrol on the way.

GF_2_m_域乘法器的快速设计及FPGA实现，ＲＳ编码及其译码都是在GF_2_m_域中进行的-Domain multiplier GF_2_m_ rapid design and FPGA realization, RS encoding and decoding are carried out in the domain GF_2_m_

基于FPGA的增量式光电编码器计数电路设计,文章含有Verileg HDL代码.-FPGA-based incremental photoelectric encoder count circuit design, the article contains Verileg HDL code.

一个UML的好资料，使用ROSE来学习一下UML，有实例的。-a UML good information, the use of ROSE to study the UML, the examples.

学习微机借口的c源程序若干，对初学者很有用处的-C-source computer to learn a number of excuses, very useful for beginners. .

CMM提问单 pdf文档-CMM single question pdf file!

模拟/混合信号：传感器连接是信号调理成功的关键 作者：Gene Heftman，特约编辑，《Electronic Design》

介绍了一种简洁可靠的嵌入式以太网接口设计-Introduce a simple and reliable embedded Ethernet Interface Design