_core_entities.md

Core Entities

Definitions

• A Circuit is a collection of Nets and Symbols
• A Symbol is an electronic component or schematic symbol
  • A Symbol can optionally point to a Circuit which implements the Symbol and is how sub-circuits are represented
  • A Symbol may optionally be part of another Symbol and is how multi-part components, such as the gates inside a single IC, are represented
• A Port is a pin or electrical connection point on a Symbol
• A Net is a collection of Endpoints representing electrically connected Ports that are wired together
• An Endpoint represents the end of a wire in a Net and can be floating or connected to a Port

Note that wires are built by the auto-router and attached to a Net as a list of wires each with a list of vertices. That is not (currently) part of the core but rather in the digilogic_routing crate.

Relationships

Here is a diagram showing how the core entities relate to one another:

erDiagram
    Circuit ||--o{ Net : has
    Net ||--o{ Endpoint : has
    Symbol ||--|{ Port: has
    Circuit ||--o{ Symbol : has
    Port }o--|| Endpoint : has
    Symbol o|--|| Circuit: "can be"
    Symbol o|--|| Symbol : "can be part of"

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• Circuits can have many Nets
  • Nets can have many Endpoints
    • An Endpoint can be linked to a Port
• Circuits can have many Symbols
  • Symbols have one or more Ports
    • A Symbol can be a Circuit
      • This is how sub-circuits are handled
    • A Symbol can be part of another Symbol
      • For example, a gate of a chip

For a list of components belonging to each entity, see the bundles file in the digilogic_core crate.

Class Diagram

Here is the class diagram of each entity with the components each would generally have:

classDiagram
    class Port {
        Name
        Number [optional]
        BitWidth
        EndpointID [optional]
        TransformBundle()
        VisibilityBundle()
        BoundingBoxBundle()
        DirectionsBundle()
    }

    class Symbol {
        Name
        DesignatorPrefix
        DesignatorNumber
        DesignatorSuffix [optional]
        SymbolKind
        Shape
        PartOf [optional]
        CircuitID [optional]
        TransformBundle()
        VisibilityBundle()
        BoundingBoxBundle()
    }

    class Endpoint {
        PortID [optional]
        TransformBundle()
        VisibilityBundle()
        BoundingBoxBundle()
    }

    class Net {
        Name
        BitWidth
        VisibilityBundle()
    }

    class Circuit {
        Name
    }

    Net --* Circuit : Circuit has many Nets
    Endpoint --* Net : Nets have many Endpoints
    Port --* Symbol : Symbols have many Ports
    Symbol --* Circuit : Circuits have many Symbols
    Endpoint <--> Port : Endpoints can link to one Port
    Symbol --|> Circuit: Symbol can be a Circuit
    Symbol --> Symbol: Symbols can be part of other Symbols

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Bundles were represented as methods mainly because mermaid expects methods on classes. They are not actually methods, but rather, bundles of components that generally belong together.

• The VisibilityBundle is attached to entities that can be visible, and inherits visibility from its parents
• The TransformBundle is attached to entities that have a location within the schematic, and can be transformed by its parent's transform
• The BoundingBoxBundle is attached to entities that take up space (that is, have a size), and are inserted into a SpatialIndex for fast lookup