Schematics define all electrical connections (and some special properties) within a PCB project. Components are placed and then wires are drawn to define connections. Further detail can then be added using classes, notes, and other tags.

CONTENTS

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Project Creation

At NER we have created a standard project template to set up new project with everything they need to get started. This means creating a new project is as simple as selecting the template:

1. X

2. X

3. X

4. X

5. X

{add images}

Basic Components and Wires

Fundamentally, all schematics consist of component symbols and wires connecting them. The following is an intro to working with these.

Placing Components

Components should be found via the component panel. It has the best organization structure and allows you to easily filter by parameter. More depth is available at https://nerdocs.atlassian.net/wiki/spaces/NER/pages/119111681/Vault+Organization#Components-Panel, but the process is summarized below:

1. Open the panel {image}

2. Select component type {image}

3. Filter results {image}

4. Select “Place” or just Click + Drag the component in {image}

5. Adjust component position as needed

When dragging a component you can:

• Spacebar to rotate

• X to mirror over X-axis

• Y to mirror over Y-axis

Placing Wires

Wires are quite intuitive to work with. A wire is started by hitting Ctrl + W and then clicking your start point. The wire will then follow your mouse as you click in between points, eventually reaching your end point.

When placing a (or dragging an existing) wire you can:

• Spacebar to toggle path

  • Basically if doing a right then left it will instead to a left then right

• {X?}

When dragging components with connected wires, the wires will attempt to stay connected. How they behave is partially dependent on selection method. It is best to learn by playing with it, but basically inclusive selection will treat wires as stiff objects, whereas exclusive selection will only keep the selected segments rigid and the rest adaptive. {this could perhaps go into an expand as it’s somewhat unneeded and confusing}

Designators (Annotation)

To manage the link between schematics, layout, and BOMs all components require unique designators. These are letter-number pairs that indicate the type of part and which instance it is within a project. Fortunately, Altium can take care of designators automatically.

Updating Designators

{directions for using the designator tool}

Designating Hierarchical Documents

{further directions for using the tools needed in hierarchy}

Improving Readability

As with all design work, schematics are used express solutions to open ended problems. With no restrictions on how solutions are approached, it is very important to document your work in a way that everyone can understand! With our team size and various experience levels there is a very wide audience that must be able to comprehend your work.

Altium has many features targeted to improve readability of schematics as well as add further information that isn’t conveyed by electrical circuits alone. The below sections will outline a few important tools for enhancing schematics.

Additionally, check out the Vault Guidelines when working on schematics. We have a handful of club-wide recommendations and requirements to setup some baseline consistency across the team.

Net Labels

Net labels serve two functions: connecting and naming. Given any existing wire in a schematic, a net label can be placed to provide a more descriptive name.

{image of a net label on a continuous wire}

These names can be very helpful for correlating schematics to the layout, as the net names will transfer into the PCB layout. It’s recommended to keep the name short but informative.

Net labels additionally can be used to actually define nets and make new connections. Duplicate net labels can be placed and Altium will consider all wires labeled the same a single net.

{image of net labels connecting things}

Net labels are frequently used for both purposes. Connections without wires are often helpful for complex schematics as well as any connections that have to otherwise traverse large portions of your page.

The Vault Guidelines highlight a few suggestions regarding how to use net labels in NER projects. {need to actually add a section and then update this link to that section}

How to Add Net Labels

Notes

As the name implies, notes are for adding notes to your schematic. These can cover anything from clarifying how a circuit works, including calculations proving functionality, or notation on how to place the components once in layout.

{directions to add notes and screenshots}

Check out the Vault Guidelines for more about how we do notes including color coding, numerical annotations, and more. {need to actual update guidelines and update link to that header}

Hierarchical Pages

Altium allows for hierarchical designs, which primarily impact schematic design, but can also be used to improve speed of layouts for large or repetitive boards.

In summary, hierarchical design is when schematic pages are embedded inside other schematic pages. This creates a tree structure that enables benefits such as reusing pages for repetitive circuits and creating organized sections of your circuitry.

{image of stacked hierarchy in shepherd}

The above screenshot shows how hierarchical design was used in Shepherd BMS 17D and the below is a example from Altium of how higher sheets connect to the lower ones via “ports.”

Setting up for Hierarchy

Altium has 5 options for “Net Identifier Scope,” which essentially defines how your hierarchy will be created. This setting is found in the project options which is found by right clicking in your schematic and selecting “Project Options,” or by opening via the task bar ({X > X > X})

{screenshots of two methods}

These options are:

• Automatic

• Flat

• Hierarchical

• Strict Hierarchical

• Global

We typically use Strict Hierarchy, which ensures that all connections between sheets must be explicitly defined with ports. You can read more about the other options here: https://www.altium.com/documentation/altium-designer/accessing-defining-managing-project-options#options

Implementing Hierarchy

Actually creating a hierarchical design is as simple as adding a sheet symbol into any schematic. From there Altium will treat your design as hierarchical according to the setting you chose above.

1. X

2. X

3. X

4. X

5. X

{show how to add sheet symbols and ports (steps and images)}

Tips on Hierarchy

Classes and Other Labels

Beyond the basics of wires and components, there are many labels that can be

{intro to more advanced annotations in Altium. Highlight how it enables automatic feature in Altium like differential pair routing, complex clearances and creepages and more}

Differential Pairs

{as title implies}

Placing Labels and Blankets

{as name implies}

Types of Labels

{bullet point all the types and benefits. If I realize this needs to be built out more I’ll do so}

Advanced Schematic Features

This section will encompass any features that we use frequently, but are beyond the scope of a basic introductory tutorial.

Busses

{talk about busses}

{More?}

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