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When importing parameters, the above often are suggested. Make sure to uncheck them. |
Symbols
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Symbol Layout
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Symbols should use imperial spacing at 100 mils.
If a more detailed symbol isn’t available, footprints should be implemented using the Altium default yellow rectangle with “small” red outline. Pins should be spaced by one 100 mil grid spacing.
Pin designators should be hidden and pin names should exactly match the datasheet (with the exception of characters that Altium doesn’t allow). Pin arrangement should match the physical footprint arrangement.
Designators
Utilize common designators for symbols. The hard-set definition we use is Appendix F of IEEE-315:
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All designator letters should be followed by “?”, as this is the wildcard for auto-generating designators. For example “D?” for diodes, “J?” for connectors, “R?” for resistors.
Footprints
All layers can adjust line width to be proportional to component size. Around 5 mils / 0.15mm is often a good starting point.
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If manufacturer CAD is not available, add an extruded model and color it to a representative hue.
Schematics
All schematic sheets must use the NER template. Tabloid is the default, but Letter size is also available.
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These are set via page properties. Click in blank space then open the properties panel. The https://nerdocs.atlassian.net/wiki/spaces/NER/pages/136314883/Schematic+Capture#Schematic-Templates page has further directions if needed. |
Multi-sheet/Hierarchy
Projects requiring multiple sheets should implement a hierarchical structure, utilizing a block-diagram style top sheet.
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It is preferential to keep a design entirely on the top sheet, if it is small enough.
Functional sections on all pages should then be designated using medium red dashed lines to define boxes.
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Style Guidelines
Signal Routing
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Net Labels
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Power & GND Labels
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Addressed Devices (I2C)
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Communication Busses
{harnesses}
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Using reference numbers
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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:
Type | Color |
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Layout Note | Light Blue |
Schematic Design Note | Default Yellow |
To-Do (typically a note for something non-critical that we should do on next revision) | Red |
BOM/Component Selection Note | Green |
If this method is used, a legend should be added to the top sheet using notes blocks.
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General Style
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Net label recommendations
Intersections of wires
When to wire vs netlabel
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