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Organization & Hierarchy

Projects requiring multiple sheets should implement a hierarchical structure, utilizing a block-diagram style top sheet.

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Functional sections on all pages should then be designated using medium red dashed lines to define boxes.

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Schematics should default to a 100 mils grid system. The grid may be reduced for placing certain components, but components and wires must be aligned to a 100 mils grid.

Signal Routing

Within functional sections of the schematic, it is recommended to utilize wires to establish connections. For longer runs, or within densely connected regions, it is best to use Net Labels. Generally, wire routing just needs to be kept readable, however the designer thinks that is best achieved.

All connections of significance should be net labeled, even if connected via wire.

Wires must be stepped away from connections by at least 1 grid spacing (100 mils)

{image of good and bad}

Four way connections must be avoided.

{image of bad and good}

Net Labels

Net labels should be used anywhere they make sense, both for connections and for just labeling purposes.

Net labels should be in full caps with underscores to separate words and suffixes.

Acronyms may be used if full name would be excessively long. A note should be added to explain acronyms if they are not self explanatory.

Power & GND Ports

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All power nets must be implemented using power ports.

The BAR power port must be used for all supply voltage nets. This includes positive and negative rails.

The GND port must be used for all GLV ground/chassis connections.

The SIGNAL ground port may be used in non-GLV ground systems. This primarily arises in isolated systems.

Communication Busses

Bussed signals, such as CAN, SPI, I2C, etc should utilize harnesses.

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Addressed Devices (I2C)

Devices with addresses set in hardware must have their address stated above the component in blue text.

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Component Placement

Components should be placed on a 100 mils grid.

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Annotations

All components must be assigned a unique designator. Use the integrated tools to complete this process automatically, as specified in https://nerdocs.atlassian.net/wiki/spaces/NER/pages/136314883/Schematic+Capture#Updating-Designators-(Annotation).

For hierarchical designs, we require the designators to be set to the format of [Type Letter][Instance Number][Sheet Letter]. This is done during the project level annotation process (https://nerdocs.atlassian.net/wiki/spaces/NER/pages/136314883/Schematic+Capture#Designating-Hierarchical-Documents) using the query $Component$Alpha.

Notes

We approve of two styles for notation. These can be used in conjunction, if the need arises.

Reference Based

Add a large Notes block to the schematic. Then add small numbers to locations in the schematic page you would like to refer to. The corresponding numbers can then be listed in order in the large notes block with commentary.

Reference numbers should be green and in parenthesis, placed with the normal text tool.

An example of these method can be seen in the above figure, “Example sheet with functional subsections”

Color Coded

Add smaller Notes blocks directly where the note is required. Add your commentary to these blocks and downsize them to match the quantity of text needed (make the text fill the block).

These notes should be color coded for visual clarity as follows:

If this method is used, a legend should be added to the top sheet using notes blocks.

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Layout

{}All schematics must be organized logically. This is typically either by placing in order of power and signal flow (inputs/supplies to the left, to outputs/loads on the right) or, for TS-GLV projects, by organizing according to isolation, placing all isolation barriers along a single line.

Style Guidelines

Schematics should default to a 100 mils grid system. The grid may be reduced for placing certain components, but components and wires must be aligned to a 100 mils grid.

Signal Routing

Within functional sections of the schematic, it is recommended to utilize wires to establish connections. For longer runs, or within densely connected regions, it is best to use Net Labels. Generally, wire routing just needs to be kept readable, however the designer thinks that is best achieved.

All connections of significance should be net labeled, even if connected via wire.

Wires must be stepped away from connections by at least 1 grid spacing (100 mils)

{image of good and bad}

Four way connections must be avoided.

{image of bad and good}

Net Labels

Net labels should be used anywhere they make sense, both for connections and for just labeling purposes.

Net labels should be in full caps with underscores to separate words and suffixes.

Acronyms may be used if full name would be excessively long. A note should be added to explain acronyms if they are not self explanatory.

Power & GND Ports

...

All power nets must be implemented using power ports.

The BAR power port must be used for all supply voltage nets. This includes positive and negative rails.

The GND port must be used for all GLV ground/chassis connections.

The SIGNAL ground port may be used in non-GLV ground systems. This primarily arises in isolated systems.

Communication Busses

Bussed signals, such as CAN, SPI, I2C, etc should utilize harnesses.

...

Addressed Devices (I2C)

Devices with addresses set in hardware must have their address stated above the component in blue text.

...

Component Placement

Components should be placed on a 100 mils grid.

Certain parameters should be displayed for every type of component. These may be modified in certain contexts if shown data is completely irrelevant. I.e. resistors used for logic may not need to show power rating.

If no parameters are shown, the MPN should be shown instead.

All components must be annotated, as described below.

Annotations

All components must be assigned a unique designator. Use the integrated tools to complete this process automatically, as specified in https://nerdocs.atlassian.net/wiki/spaces/NER/pages/136314883/Schematic+Capture#Updating-Designators-(Annotation).

For hierarchical designs, we require the designators to be set to the format of [Type Letter][Instance Number][Sheet Letter]. This is done during the project level annotation process (https://nerdocs.atlassian.net/wiki/spaces/NER/pages/136314883/Schematic+Capture#Designating-Hierarchical-Documents) using the query $Component$Alpha.

Notes

We approve of two styles for notation. These can be used in conjunction, if the need arises.

Reference Based

Add a large Notes block to the schematic. Then add small numbers to locations in the schematic page you would like to refer to. The corresponding numbers can then be listed in order in the large notes block with commentary.

Reference numbers should be green and in parenthesis, placed with the normal text tool.

An example of these method can be seen in the above figure, “Example sheet with functional subsections”

Color Coded

Add smaller Notes blocks directly where the note is required. Add your commentary to these blocks and downsize them to match the quantity of text needed (make the text fill the block).

These notes should be color coded for visual clarity as follows:

If this method is used, a legend should be added to the top sheet using notes blocks.

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Layout

Design Rules

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Layout

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Silkscreen

All designators should be shown.

Font style should be stroke, and font size may be adjusted according to density. However, ensure you stay within fabrication limits.

Board Outline

The board outline must be represented in a mechanical layer. For our boards this is typically M1. The board outline layer should include the outer boundary as well as any slots, cutouts, etc.