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This TechWatch is based on the first part of my Design Reuse with Altium Designer presentation from our user conference on the 31st October 2006. The rest of the topics will be covered in future TechWatch's. The files for this and all of the other TechWatch's in the Design Reuse series can be downloaded here (451kb). In this TechWatch we will be working with files from the 'Snippet and Multi-Channel Design files' folder.

Design Reuse Introduction

Reusing parts of an existing design is not a new idea. With the advent of soft design techniques, reconfigurable platforms and IP, design reuse is one of the hot topics for modern electronics design. As usual the term is not well-defined, so one vendor’s design reuse features are not the same as another's. This and forthcoming TechWatch's will explore the concepts and operation of Altium Designer with respect to design reuse and will act as a technical backgrounder for customers wishing to exploit Altium Designers’ capabilities in this area.
 

Design Reuse methodologies can be implemented as a number of “layers”

Layer 1: Features that allow fast and “intelligent” cloning of localised circuitry.

Layer 2: Reusing entire schematic sheets and multi-channel design techniques.

Layer 3: Creation of re-usable, pre-verified, core “components” stored in libraries.

Layer 1:

Design Snippets

When a design includes sections of circuitry used in other designs then a designer can make good use of the Design Snippets feature. A simple and easy to use feature, the Snippets system lets you save any selection of circuitry on a single schematic sheet, or any selection of a PCB design, including the components and the routing.

Let’s start by looking at the Snippets panel. This panel displays all available snippets. Here we can see some existing snippet examples organised into folders for text-based, PCB and Schematic snippets. They each have a description and thumbnail which makes them easy to locate.

Any windows folder can be used regardless of whether it’s on your own machine or on a network drive. With network drives you can set up a centralised collection of Snippets and share them with the rest of your organisation. We have a 'Snippets' folder which we will now link to. Clicking on the Snippets Folders… button allows us to navigate to the folder and give us access to the Snippets. You will see a PCB snippet available.

Click on the Power.PrjPCB from the 'Power' folder. We will now create our own Snippet from the Power.SchDoc. This sheet has circuitry that we want to use in our current design. It is very easy to create a Snippet, simply select the objects you want to reuse then right click and select Snippets ›› Create Snippet from selected objects. Choose to add it to the Schematic folder and don't forget to add a comment to the Snippet. This is important for reference, not only for the person creating the Snippet but for users who may be looking for it in the future. Now that the Snippet is stored we can switch to the Power.SchDoc in the Mixer.PrjPCB and place the Snippet into the design by right clicking the Snippet from the Snippets panel and choosing to Place Snippet. The Snippet will now be attached to your cursor and can be placed by left clicking the mouse.

Now we will add an equivalent PCB Snippet to the PCB using the same method. Open the Mixer_Placed.PcbDoc. You will see the Power section is empty. This is available as a Snippet. Go to the Snippets panel, select and place the PCB Snippet.

So, you have now placed a schematic Snippet and the equivalent PCB Snippet. Now we have to synchronise the schematic and PCB documents using the Project ›› Component Links command. This will check the status of the links between schematic components and their corresponding PCB footprints. We can see that they all match up by designator in this case. If they did not you would need to Re-annotate. As the PCB snippet does not contain net information we will now run a Design ›› Import Changes to bring over this information from the schematic.

In the next TechWatch we review Layer 1 and move on to Layer 2 where we look at larger forms of Design Reuse involving entire schematic sheets.