• Hardware Development
• Circuit Design

Hello community,

 

I know that in last posts I have been writting about the Software. But what about Hardware? In last months I have been dealing with it, exactly with OrCAD 16. And I will explain how to build a PCB  in 2 articles. For begginers could be a good and easy guide.

This article explains the part for the designing of the schematic, and in the next one which i will explain the layout part.

The first stuff you must known about OrCAD is that it is not an unique tool for hardware designing as PCAD. OrCAD it is a suite for multiple tools. Here you have the list of tools/programs and brief description:

• OrCAD Capture and OrCAD Capture CIS: This tool it is for the development of the schematic.
• OrCAD Layout (and its variants) and OrCAD PCBDesigner: This tool it is used for the development of the photolithographs need to the production of the PCB.
• PSpice: This tool is used for the simulation of analog/mixed-signal circuits, generally designed in the other tools.
• More: The other tools by now I did not use, so I will not explain them in this post.
  

All the products are interconnected between each other. I mean if you developed an schematic with Capture, then you use Layout to developed the physical PCB.

After this introduction the first step for obtaining a PCB with OrCAD 16, it is to develop the schematic in OrCAD Capture.

Building the Schematic in OrCAD Capture

Upon opening the application, for build a new design you must go to "File->New->Project" and in the prompt window fill the name of your project and choose the "Schematic" option. After that, press the "OK" button. For default the program creates you a project window and a page for the schematic.

The project window it is show as a Windows Explorer format, divided in folders. At top folder it is "Design Resources". There are several files and subfolders inside it:

• project_name.dsn: It groups the schematics for your designs. There is a root folder inside it marked with the symbol "/". There resides the main design page. For deafult its name is "SCHEMATIC1", you could change it by rigth-click and chosing the "Rename" option. Inside the "SCHEMATIC1" there are the pages of our designs. For default the application wizard creates only 1 page named "PAGE1", the name could be changed similar the previous one. Also it could be added more pages with rigth click in the "SCHEMATIC1" Subfolder and choosing the "New Page" option. The last stuff that appears here it is the "Design Cache" Subfolder. There resides the parts cache and some options cache that appears on the schematic page. It is important to understand that when you inserts a part or an option into the design, the program creates a local copy with this part or option in your project, and it is the one it uses. It means that if you change the part in the part library, it will not change in the design until you enter in this folder and in the part or option do rigth-click and in choose the "Update Cache" option, be careful with this because the schematic could be changed.
• Library: In it resides the user part library. For default OrCAD gives a part library, but there there are not all the componens, so here you must include the library/libraries for the parts that are not included. Also you are able to add your own designed parts to one of the libraries listed there. This is made by rigth-click in the choosen library and select the "New Part" Option (if there is not any library, create a new library in "File->New->>Library").

The next folders are "Output" and "Referrenced Projects". As you could imagine in the "Output" appeares the generated files obtained from the process of the you design.

The next step it is to create the design in the page/pages you want. For this there are several books where it explains all in more detail. I recommend this book: "Complete PCB Design Using OrCad Capture And Layout".

With the design completed, the next step it is to create the Output of your design. For this purpose OrCAD includes several Tools:

• Annotate
• Back annotate
• Design Rules Check
• Create Netlist
• Cross Reference Parts
• Bill of Materials

This Tools are accesible in the menu "Tools". The main important one it is the "Create Netlist". This tools created the netlist needed for the layout program and it is the only one i will explain how to use.

First select the "project_name.dsn" from the project window, then left-click on the menu "Tools->Create Netlist". After this select the "Layout" tab. There you must choose between inches or milimeters. In my case I'm used to milimeters so i choose always this option (note that this it is important for the layout program, if you are going to develop in metric or not). Chose the place where it will be saved the output file and press OK button. If all the design it is OK you will see in the "Output" folder a new File with the *.mnl extension. If not, check the log file and correct the errors.

In the next post I will explain the layout part, with the "project_name.mnl" as an input. But before to this it is needed to create or have the libraries for the footprints of the components you use, so I will post an intermediate article for this purpose.

And if any of you have doubts, please comment. I will try to answer as soon as possible.

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