Archive for March, 2013

OrCAD Vs Design Entry HDL ( Concept HDL)

March 26th, 2013

Cadence has two different ways of allowing you to enter schematics. The first is OrCAD - which is more popularly used by most designers. OrCAD impresses with its intuitive appeal and it looks like it was developed by the engineers and for the engineers, or may be there was a good communication between the software engineers and the hardware designers. OrCAD was not a native part of Allegro's Cadence. Cadence purchased OrCAD and integrated its Schematics drawing tool with its popular Layout tool.

Design Entry HDL ( previously known as Concept HDL), is the second of the two schematics entry tool. It was developed as a native Schematics Design Entry tool with many more options than provided by OrCAD. For example, you can enter the details of a component through an XL sheet. We have the concept of Verilog modules which can be handy if you are integrating and performing simulation with Verilog ( or VHDL) at module level. Design Entry also has a number of versatile support, like Constraint management, which comes handy for High Speed designs.

However, the Design Entry HDL is not intuitive. The learning curve is longer and the number of files required to manage the library and the project is large. With OrCAD you just need one file - the .dsn file.

Reference Designer has recently started providing beginner level training for Design Entry HDL in addition to OrCAD. Please contact us for any of your training needs.

You can also check out online learning materials for Design Entry HDL and OrCAD .


free signal integrity simulation Tool / software

March 23rd, 2013

We recently spotted a free free signal integrity simulation Tool / software called quite universal circuit simulator or qucs for short.

We started playing with this software and have started to work on a tutorial about that that you can access here.


New Tutorial for Apple

March 15th, 2013

We started two new tutorials aimed at Apple's environments. The first is an objective C tutorial and the second is the iOS tutorial .

The Objective C tutorial will create a basic building block, which you will be required when you use start learning the iOS. For those uninitiated, iOS is used to develop application for the iPad and iPhones.

The importance of learning iOS is evident from the fact that, half of the smartphones shipped today are from Apple. And half of tablets shipped today are also from Apple ( of course give of take 5 to 10% here and there). This creates a huge demand for the App developers. The combination of the requirement of hardware and software dictates that there are lesser number of the developers available as compared to the requirement. We hope that these tutorials fulfills the need of those looking to learn the Apple's paradigm.


Learning through cloud

March 8th, 2013

A large number of readers have endorsed the usefulness of our javascript and jQuery tutorial. One of the key reasons of its success is its ability to allow users to do coding right on the website while learning. It allows them to make changes in the code and then check the "what if" scenario.

Fortunately the solution is easy with the javascript, jQuery or the HTML, HTML5 , CSS and similar learning tutorial that primarily rely upon the browser's client interpretability. But if we wish to extend the same thing to other tutorials, like PHP, Python or C#, the solution is not easy, especially if we consider its security implications. For example, if we allow a user to run a PHP code, we are essentially allowing his code to travel to the server, and run the PHP code on the server itself. This means that the solution is not trivial.

Other tutorials have similar implications.

We are contemplating some of the open source codes that can run on server and provide results to the users. For example, we could install the Icarus software on Linux and, using PHP SSH2 extension, we could be running a shell command from PHP. So basically, user can visit our Verilog tutorial and enter the Verilog code in a text area. The content of the textarea will be saved in a temporary file on the server. Using PHP SSH2 this temporary file will be stored on the server. The Using PHP SSH2, we will issue the command to run Iracus on the server and then collect the output. The output is then stored on the Linux machine that has Icarus. We can then use PHP SSH2 to access the output, which will then travel back to the user's second textarea to display results.

Seems easy ?

We are not sure. In the coming weeks, this is something we will be trying. Stay tuned and, in the meantime look at our tutorials in general and Verilog Tutorial in particular.


New AJAX and jQuery AJAX Tutorial

March 8th, 2013 is pleased to announce new AJAX and jQuery AJAX tutorial. The AJAX tutorial can be accessed here while the jQuery AJAX tutorial can be accessed here .

These tutorials are kind of an extension of our already popular javascript and jQuery tutorials. They come with real life examples and more importantly you can practice and make changes in the code while learning. This speeds up the learning process.

We encourage readers to read the tutorial and then make changes in the code on the fly to see what works and what does not work.


Errata - Signal Integrity for PCB Designers

March 5th, 2013

The 1st ( and the only edition ) of the Signal Integrity for PCB Designers has some errors crept into it. This post enlists the errors

1. Page 101
Incorrect - T = Trace thinkness
Correct - T = Trace thickness

2. Page 106
Incorrect - These formula were designed
Correct - These formulae were designed

3. Page 110
Incorrect - t =  trac thickness
Correct - t =  trace thickness

4. Page 125
Incorrect  Figure 9-19 says it is stripline
Correct  It should be Microstrip

5. Page 131
Incorrect - ...the amount of the reflection depends upon the ration of the of the incident ...
Correct - ...the amount of the reflection depends upon the ratio of the of the incident ...

6. Page 139
Incorrect - faraad
Correct -  farad

7. Page 140
Incorrect - ., the refelection coefficient is given by
Correct - , the reflection coefficient is given by

8. Page 144
Incorrect - The source and and far end reflection functions are given by
Correct - The source and  far end reflection functions are given by

9. Page 157
Incorrect - ., The input to hspice is a simple text file with .sp extention
Correct - , The input to hspice is a simple text file with .sp extension

10. Page 181
Incorrect -  The Table below shows the measured amplitude

Correct - The figure below shows the measured amplitude

11. Page 194
Incorrect - the cross talk may be low enough with 12 mil seperation not to require guard traces
Correct - the cross talk may be low enough with 12 mil separation not to require guard traces

12. Pages 200 to 208

Incorrect - Headings say - Designing for EMI Compliance

Correct - should be Characterization of High Speed Bus

13. Page 212 - The font of following is different

l =   is the length of a segment

14. Page 233
Incorrect - Check spelling of Copper, aneealed
Correct - Should be Copper, annealed

14. Page 234
Incorrect - Check spelling of Aluminium
Correct - Should be Aluminum