Schematic capture

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Schematic capture or schematic entry is a step in the design cycle of electronic design automation (EDA) at which the electronic diagram, or electronic schematic of the designed electronic circuit, is created by a designer. This is done interactively with the help of a schematic capture tool also known as schematic editor.^[1]

The circuit design is the first step of actual design of an electronic circuit. Typically sketches are drawn on paper, and then entered into a computer using a schematic editor. Therefore schematic entry is said to be a front-end operation of several others in the design flow.^[2]

Despite the complexity of modern components – huge ball grid arrays and tiny passive components – schematic capture is easier today than it has been for many years.^[3] CAD software is easier to use and is available in full-featured expensive packages, very capable mid-range packages that sometimes have free versions and completely free versions that are either open source or directly linked to a printed circuit board fabrication company.

In past years, schematic diagrams with mostly discrete components were fairly readable. However, with the newer high pin-count parts and with the almost universal use of standard letter- or A4-sized paper, schematics have become less so. Many times, there will be a single large part on a page with nothing but pin reference keys to connect it to other pages.

Readability levels can be enhanced by using buses and superbuses, related pins can be connected into a common bus and routed to other pages. Buses don't need to be just the traditional address or data bus directly linked pins. A bus grouping can also be used for related uses, such as all analog input or all communications related pin functions.