Designing for Reuse in Altium Designer

The term 'design reuse' has become something of a cliche in the marketing of engineering products, perhaps primarily driven by how little of it actually happens. The same design task is performed over and over; however, in electronics design, design reuse is practiced every day by every engineer using off-the-shelf integrated circuits. These devices are a package of electronics that someone, somewhere, has designed, tested, documented, and sold to the world at large. Every customer of this device is reusing this design in a very rigorous way.

In comparison, the real practice of design reuse in the rest of the design process is generally very poor and most likely consists of a variety of glorified copy-and-paste tools. Altium Designer offers a variety of solutions in support of design reuse, facilitating streamlined design without the need to reinvent the wheel.

Reuse Blocks and Design Snippets

Related page: Reuse Blocks & Snippets

If your designs often include common 'sections' of circuitry, Altium Designer provides a simple and easy way to save and reuse sections of design circuitry, both Workspace-based and local, file-based. Such sections can be added to any PCB design without having to start from scratch each time. This is a great feature for those often-used fragments and smaller sections of circuitry that you want to reuse. The system lets you save any selection of:

• Circuitry on a single schematic sheet (a schematic snippet).
• Circuitry in a PCB design, including the components and the routing (a PCB snippet).

When connected to a Workspace, you can create a single entity – a reuse block – that can contain both schematic circuitry and its physical representation for the PCB. When such a reuse block is placed on a schematic sheet, its physical representation will be placed automatically in the PCB document during the ECO process.

The Design Reuse panel is the central point for creating, managing and placing reuse blocks and snippets of design circuitry.

A circuit snippet or 'reuse block' can be added to any design without having to start from scratch each time.

Managed Schematic Sheets

Related page: Managed Schematic Sheets

Being able to reuse design content is something that all product development companies want and can greatly benefit from. Not only does reuse save time, but being able to easily reuse a section of a previous design means that all the qualification and testing of that part of the design is done. Design reuse is much more than copy and paste, though; true reuse requires the content to be locked down, so you are guaranteed that it is the same as before. No quick edits to change the color of a component or a tweak to a resistor value. Working with reusable content must be like working with off-the-shelf components; place the content, wire it in, and it works just like it did last time.

Altium Designer, in conjunction with your Workspace, allows you to create managed schematic sheet items directly within the Workspace. Once a managed schematic sheet item has been created (and data released into a revision of it) and its lifecycle state is set to a level that the organization views as ready for use at the design level, it can be reused in future board-level design projects.

Formally release a sheet of design circuitry that can then be re-used as a revision of a managed schematic sheet item in other design projects requiring that same functionality.

A managed sheet is a standard Altium Designer schematic sheet that contains components and wiring stored in a Workspace so it can be reused in other designs. It is edited like any other schematic sheet. The Managed Sheet concept is not limited to a single schematic sheet. You can place a managed sheet in your design that is at the top of a tree of other managed sheets.

The decision to move from device sheets to managed sheets comes when there is a desire to transition from re-useable content to managed re-useable content – that is, when there is a desire or need to control the release, revision status and lifecycle state of the design content.

By making it managed content, you can be sure that the revision of a managed sheet that you use in a design can be easily identified and traced back to its source whenever needed. Additionally, because it is managed content, it can be revised and updated when needed, and the usage relationships can all be traced down to the components on the sheet and up to the designs that use it. This ensures you have all the information needed to decide if the revised sheet must be pushed to existing designs or if a particular design must continue to use the previous revision.

Device Sheets

Related page: Device Sheets

Device sheets simplify the design process by providing modularized and consistent building blocks that can be reused between projects. Device sheet symbols are placed and referenced similarly to components. They function in the same way as sheet symbols and schematic documents but are not explicitly added to projects.

Device sheets are stored as normal schematic documents in special device sheet folders. They are placed and referenced in your project, similarly to a simple component. Device sheets are included in the project hierarchy and are distinguished from standard schematic documents by a different icon in the Projects panel.

Example of a read-only device sheet. There is also a read-only watermark with a device sheet (recycle) watermark. The sheet itself resides in a device sheet folder on the local or network drive and is included in a project (referenced) through the placement and definition of a device sheet symbol on the parent sheet above.