2009 Coming

Merry Christmas & Happy New Year!

diff in linux

diff在linux下用来比较两个文件或者文件夹的内容，具体使用可以参考http://linux.about.com/library/cmd/blcmdl1_diff.htm，其中-b可以比较不同类型的文件，如dos，unix，但经实践证明，如果两个文件类型不一样，且文件比较大，如大于1MB时，比较时间会很长，why?
如果我们把Windows下产生的文件在linux下执行一次dos2unix，转换成unix类型，然后再用diff比较，时间将大大减少。仅试过文本文件。

Virtex5 DSP48E Synplify8.6.2 bug?

最近工作中遇到的一个问题，不知道是否是工具的bug，在此备案。
问题描述：设计中所用到的一个乘法器，在fpga验证时不能工作，用逻辑分析仪查看得知乘法器输入正确，但输出有问题。通过多次修改并用综合后的网表仿真得知是synplify在综合时调用DSP48E时处理出错，具体分析如下：
环境：Xilinx的Virtex5 LX系列FPGA，Synplify8.6.2综合，ISE9.2实现，Modelsim后仿
设计背景：乘法器的输入，一端为寄存器直接输出，另一端是比较复杂的组合逻辑，输出结果再做加法等运算，然后送入寄存器。
DSP48E简介：
Virtex-5 DSP48E Slice 包含 Virtex-4 DSP48 的所有功能以及多种新功能。这些新功能包括
一个更宽的 25 x 18 乘法器和一个扩展后用作逻辑单元的加/ 减功能。
看框图：

其中输入可以有两级寄存器，所以在做优化的时候会把外面的寄存器放到里面，而这两级寄存器分别有两个EN端，当只用其中一个时，会使用REG2，可以从仿真的model中间可以看到详细的描述，但Synpilfy在处理这种情况时，使用的是REG1 ，此时CE2常为1，所以导致输入数据不能在正确的时刻被latch，进而导致输出错误。
在搜索时发现Xilinx自己的工具，如coregen之类的在处理DSP48E时也出现过不少bug，synplify也是从8.6版本才开始支持virtex5的，所以我觉得很有可能是工具在这有bug，目前synplify的版本已达9.6以上，估计新版本不会再有此问题。
总结：
1、尽量不要用工具最新的功能，关注工具新版的release notes
2、FPGA做逻辑验证的时候最好不要使用FPGA的特殊单元，也不要让工具做太多的优化，除非timing确实有问题
3、出了问题应该先分析问题，不要一上来就尝试各种修改的办法。（这点我开始认为自己的coding style有问题，让工具犯傻了，所以修改了好几次，均已失败告终）

IPcore Release Package

IPcore Release Package Should include:

1. Synthesizable Verilog RTL
   
2. Bit-accurate C model
   
3. Verilog testbench
   
4. Detailed product documentation
   
5. Design specifications
   
6. Integration guidelines
   
7. Complete verification suite
   
8. VHS tape with example noisy signals
   
9. Extensive tests including corner-case scenarios
   
10. Golden test result vectors
    
11. FPGA test board (with testbench and supporting files)
    
12. Support and training
    
13. to be added...

清除所有.svn目录

一、在linux下

删除这些目录是很简单的，命令如下
find . -type d -name ".svn"|xargs rm -rf

或者

find . -type d -iname ".svn" -exec rm -rf {} \;  

全部搞定。

二、在windows下

1、在项目平级的目录，执行dos命令： 
xcopy project_dir project_dir_1 /s /i

2、或者在项目根目录执行以下dos命令 
for /r . %%a in (.) do @if exist "%%a\.svn" rd /s /q "%%a\.svn"

3、直接用windows的搜索功能，打开搜索隐藏文件的选项，然后搜索.svn，再一起删除即可

Power Savings Techniques

From snug San Jose -- Power Analysis Methodology
From Spreadsheet to Sign-off by George Cuan, Cisco Systems, Inc.

async fifo design

Key points:
1. fifo body: dual ports sram or registers array
2. read and write address for sram
3. empty and full flag for the fifo body, it's the most important, and there are two methods presented in the reference paper.
4. almost empty or almost full flag, if needed
5. fifo content depth or fifo space depth, if needed
6. some special case for the special application, eg.  the predicable  r/w clock frequence ratio.

Reference paper:
 http://www.sunburst-design.com/papers/

H.264 Baseline Decoder from opencores

    Nova is a low-power realtime H.264/AVC baseline decoder of QCIF resolution, targeting mobile applications. It is a dedicated, full hardwired and self-contained ASIC design without utilizing any GPP/DSP cores. It has been successfully verified on Xilinx Virtex-4 FPGA and 0.18um ASIC chip. The measured power consumption is 293uW@1V for 30fps QCIF decoding.

Introduction page:http://www.opencores.org/projects.cgi/web/nova/overview 

source code download[http]:http://www.ipcore.cn

Berkeley University EECS Course WEB Sites

http://inst.eecs.berkeley.edu/classes-eecs.html

There are many EE classes online, so good for the EE students and RDs.

EECS1 Introduction to EECS
EECSBA1 Strategic Computing and Communications Technology
EECS20N Structure and Interpretation of Systems and Signals
EE24 Freshman Seminar
EE40 Introduction to Microelectronic Circuits
EE42 Introduction to Digital Electronics
EE43 Introductory Electronics Laboratory
EE98 EE 98 Seminar Home Pages
EE100 Electronic Techniques for Engineering
EE104 Linear and Nonlinear Circuits
EE105 Microelectronic Devices and Circuits
EE117 Electromagnetic Fields and Waves
EE117B Electromagnetic Fields and Waves II
EE118 Introduction to Optical Communication Systems
EE119 Introduction to Optical Engineering
EECS120 Signals and Systems
EE121 Introduction to Digital Communication Systems
EE122 Introduction to Communication Networks
EE123 Digital Signal Processing
EE125 Introduction to Robotics
EE126 Probability and Random Processes
EE128 Feedback Control
EE129 Neural and Nonlinear Information Processing
EE130 Integrated-Circuit Devices
EE131 Semiconductor Electronics
EE136 Introduction to Quantum and Optical Electronics
EE140 Linear Integrated Circuits
EE141 Introduction to Digital Integrated Circuits
EE142 Integrated Circuits for Communications
EE143 Microfabrication Technology
EE145L Introductory Electronic Transducers Laboratory
EE145M Intro Microcomputer Interfacing Lab
EE145A (renamed to EE145L)
EE145B Image Processing and Reconstruction Tomography
EE146 unknown
EECS150 Components and Design Techniques for Digital System...
EECS152 Computer Architecture and Engineering
EE192 Mechatronics
EE194 EE 194 Seminar Home Pages
EEH196A Senior Honors Thesis Research
EE198 EE 198 Seminar Home Pages
EE199 Independent Study
EE201 Strategic Computing and Communications Technology
EE210 Applied Electromagnetic Theory
EE210B Applied Electromagnetic Theory
EE213 Soft X-Rays and Extreme Ultraviolet Radiation
EE217 Microwave Circuits
EE219 unknown
EE219A Computer-Aided Verification of Electronic Circuits
EE219B Logic Synthesis for Hardware Systems
EE219C Computer-Aided Verification
EE220 Neural & Nonlinear Information Processing
EE221A Linear System Theory
EE222 Nonlinear Systems--Analysis, Stability and Control
EE223 Stochastic Systems: Estimation and Control
EE224A Digital Communications
EE224B Fundamentals of Wireless Communications
EE225D Audio Signal Processing
EE225A Digital Signal Processing
EE225B Digital Image Processing
EE225C VLSI Signal Processing
EE226 unknown
EE226A Random Processes in Systems
EE227A Introduction to Convex Optimization
EE228A Communication Networks
EE229 Information Theory and Coding
EE229B Error Control Coding
EE230 Solid State Electronics
EE231 Solid State Devices
EE232 Lightwave Devices
EE233 Lightwave Systems
EE235 Nanoscale Fabrication
EE236A Quantum and Optical Electronics
EE238 Superconductive Devices and Circuits
EE240 Analog Integrated Circuit Design and Analysis
EE241 Advanced Digital Integrated Circuits
EE242 Advanced Integrated Circuits for Communications
EE243 Advanced IC Processing and Layout
EE244 Computer-Aided Design of Integrated Circuits
EECS245 Introduction to MEMS Design
EE246 Microelectromechanical Systems (MEMS)
EE247 Analysis and Design of VLSI Analog-Digital Interfac...
EE249 Embedded System Design
EE290D Advanced Topics in Semiconductor Technology
EE290E Advanced Topics in Electromagnetics and Plasmas
EE290F Advanced Topics
EE290G (renamed to EE245)
EE290H Semiconductor Manufacturing
EE290I Advanced Topics in Wireless Communication
EE290J Advanced Topics in Electrical Engineering
EE290N Advanced Topics in System Theory
EE290O Advanced Topics in Control
EE290Q Advanced Topics in Communication Networks
EE290S Advanced Topics in Communications and Information T...
EE290T Advanced Topics in Signal Processing
EE290X Advanced Topics in Management and Social Issues in ...
EE290Y Organic Materials in Electronics
EE290A Advanced Topics in Computer-Aided Design
EE290B Advanced Topics in Solid State Devices
EE290C Advanced Topics in Circuit Design
EE291 Control and Optimization of Distributed Parameters ...
EE291E Hybrid Systems and Intelligent Control
EE297 Field Studies in Electrical Engineering
EE298 EE 298 Seminar Home Pages
EE299 Individual Research
EE301 Teaching Techniques for Electrical Engineering