Hierarchical designs

A hierarchical design is a design with more that one sheet. To be able to use more than one sheet an interface has to been used to connect the different sheets with each other. The interface used, consists of sheet symbols in one sheet, and external connections on other sheets. To make this more understandable an example will be used.

In a hierarchical design there is always a start sheet, the so called top sheet. In this top sheet, sheet symbols are included. Every sheetsymbol represents an other (sub)sheet. The name of the sheetsymbol represent a sheet with the same name. The pins defined in the sheetsymbol represents the external connections of the subsheet. The label name of a pin in the sheet symbol must be the same, as the name of the external connection in the subsheet. Also the pin type (Input,Output,I/O) must be the same. Every subsheet can also contain sheetsymbols which represents further subsheets.