:author: The KiCad Team
:doctype: book
:toc:
:ascii-ids:


= Introduction

[[copyright]]
*Copyright*

This document is Copyright (C) 2021 by its contributors as listed
below. You may distribute it and/or modify it under the terms of either
the GNU General Public License (http://www.gnu.org/licenses/gpl.html),
version 3 or later, or the Creative Commons Attribution License
(http://creativecommons.org/licenses/by/3.0/), version 3.0 or later.

All trademarks within this guide belong to their legitimate owners.

[[contributors]]
*Contributors*

Jon Evans

[[feedback]]
*Feedback*

The KiCad project welcomes feedback, bug reports, and suggestions related to the software or its
documentation. For more information on how to sumbit feedback or report an issue, please see the
instructions at https://www.kicad.org/help/report-an-issue/

[[publication_date]]
*Publication date*

2021-05-09


[[welcome]]
== Welcome

KiCad is a free and open-source electronics design automation (EDA) suite. It features schematic
capture, integrated circuit simulation, printed circuit board (PCB) layout, 3D rendering, and
plotting/data export to numerous formats. KiCad also includes a high-quality component library
featuring thousands of symbols, footprints, and 3D models. KiCad has minimal system requirements
and runs on Linux, Windows, and macOS.

KiCad 6.0 is the most recent major release.  It includes hundreds of new features and bug fixes.
Some of the most notable new features include:

- A new schematic file format that embeds schematic symbols that are used in a design, meaning
  there is no longer the need for a separate cache library file.
- A new project file format that separates out display settings (such as which layers are visible
  in the PCB editor) so that these types of settings no longer cause changes to the board file or
  main project file, making KiCad easier to use with version control systems.
- A major overhaul of the schematic editor bringing its behavior in line with the PCB
  editor and conventions used by most other graphical editing software.  Object selection and
  dragging now works the way most users expect when coming from other software.
- Support for buses of arbitrary signals, custom wire and junction colors per net, alternate pin
  functions, and many other new schematic features.
- A new design rule system in the PCB editor supporting custom rules that can be used to constrain
  complex designs with high voltage, signal integrity, RF, or other specialty needs.
- A number of improvements to the PCB editor's capabilities, including support for rounded (arc)
  track routing, hatched zone fills, rectangle primitives, new dimension styles, removing pad and
  via copper on unconnected layers, object grouping, locking, and much more.
- More flexible configuration of mouse behavior, hotkeys, color themes, coordinate systems,
  cross-probing behavior, interactive routing behavior, and much more.
- A new side panel UI for the PCB editor featuring layer visibility presets, opacity control of
  different object types, per-net and per-netclass coloring and visibility, and a new selection
  filter to control what types of objects can be selected.
- A redesigned look and feel, including a new design language used for all tool icons, a new
  default color theme, and support for dark window themes on Linux and macOS.

A full listing of new features and changes in KiCad 6.0 can be found
https://www.kicad.org/blog/2021/12/KiCad-6.0.0-Release/[here].

[[installing-and-upgrading]]
== Installing and Upgrading KiCad

KiCad maintains compatibility and support with the maintained versions of Microsoft Windows, Apple
macOS, and a number of Linux distributions.  Some platforms have specific installation or upgrade
instructions. Always check https://www.kicad.org/download/ for the latest release information and
instructions for your platform.

KiCad may compile and run on platforms that are not officially supported.  The KiCad development
team makes no guarantees that KiCad will continue to work on these platforms in the future.  See
https://www.kicad.org/help/system-requirements/ for more details on supported platforms and
hardware requirements.

KiCad uses a "major.minor.point" release version format.  Major releases bring new features and
other significant changes to the code.  Minor releases are relatively rare and typically bring bug
fixes that are too complicated for a point release.  Point releases contain only bugfixes.  Users
are encouraged to update to the latest point release for their current major.minor version
promptly, as these releases will not break file compatibility.  Major releases almost always come
with changes to file formats.  KiCad is in general always backwards compatible with files created
by older versions, but not forwards compatible: Once files are edited and saved by a new major
version, these files will not be openable by the previous major version.

=== Migrating from Previous Versions

In general, to migrate a design to a new version of KiCad, simply open the project with the new
version, then open the schematic and PCB and save each file.  More details about specific issues
that may come up when migrating designs is covered in the Schematic Editor and PCB Editor chapters
of the manual.

NOTE: Make sure to save a backup of your design before opening it with a new version of KiCad.

The symbol library format has changed in KiCad 6.0.  To continue editing symbol libraries made with
a previous version of KiCad, these libraries need to be migrated to the new format.  For details on
this process, see the Schematic Editor chapter of the manual.  Symbol libraries that have not been
migrated can still be opened and used in read-only mode.

[[kicad-work-flow]]
== KiCad Workflow

This section presents a high-level overview of the typical KiCad workflow.  Note that KiCad is a
flexible software system, and there are other ways of working that are not described here.  For
more information about each of the steps described in this section, please see the later chapters
in this manual.

NOTE: A number of tutorials and guided lessons in using KiCad have been created by community
      members.  These resources can be a good way to learn KiCad for some new users.  See the
      Further Reading section at the end of this chapter for more information.

[[basic-terminology]]
=== Basic Terminology

KiCad uses a number of terms that are fairly standard in the area of electronics design automation
(EDA) software, and some that are more specific to KiCad.  This section lists some of the most
common terms used throughout KiCad's documentation and user interface.  Other terms that are more
specific to a certain part of the KiCad workflow are defined later in this manual.

A **schematic** is a collection of one or more pages (sheets) of circuit schematic drawings.  Each
KiCad schematic file represents a single sheet.

A **hierarchical schematic** is a schematic consisting of multiple pages nested inside each other.
KiCad supports hierarchical schematics, but there must be a single **root sheet** at the top of the
hierarchy.  Sheets within a hierarchy (other than the root sheet) may be used more than once, for
example to create repeated copies of a subcircuit.

A **symbol** is a circuit element that can be placed on a schematic.  Symbols can represent
physical electrical components, such as a resistor or microcontroller, or non-physical concepts
such as a power or ground rail.  Symbols have **pins** which serve as the connection points that
can be wired to each other in a schematic.  For physical components, each pin corresponds to a
distinct physical connection on the component (for example, a resistor symbol will have two pins,
one for each terminal of the resistor).  Symbols are stored in **symbol libraries** so they can be
used in many schematics.

A **netlist** is a representation of a schematic that is used to convey information to another
program.  There are many netlist formats used by various EDA programs, and KiCad has its own
netlist format that is used internally to pass information back and forth between the schematic and
PCB editors.  The netlist contains (among other things) all the information about which pins
connect to each other, and what name should be given to each **net**, or set of connected pins.
Netlists can be written to a **netlist file**, but in modern versions of KiCad, this is not
necessary as part of the normal workflow.

A **printed circuit board**, or PCB, is a design document that represents the physical
implementation of a schematic (or technically, a netlist).  Each KiCad board file refers to a
single PCB design.  There is no official support for creating arrays or panels of PCBs within
KiCad, although some community-created add-ons provide this functionality.

A **footprint** is a circuit element that can be placed on a PCB.  Footprints often represent
physical electrical components, but can also be used as a library of design elements (silkscreen
logos, copper antennas and coils, etc.).  Footprints can have **pads** which represent copper areas
that are electrically-connected.  The netlist will associate symbol pins with footprint pads.

A **worksheet** is a drawing template, typically containing a title block and frame, that is used
as the template for schematic sheets and PCB drawings.

**Plotting** is the process of creating manufacturing outputs from a design.  These outputs may
include machine-readable formats such as Gerber files or pick-and-place listings, as well as
human-readable formats such as PDF drawings.

**Ngspice** is a mixed-signal circuit simulator, originally based on Berkeley SPICE, that is
integrated into KiCad's schematic editor.  By using symbols with attached SPICE models, you can run
circuit simulations on KiCad schematics and plot the results graphically.

[[kicad-programs]]
=== KiCad Components

KiCad consists of a number of different software components, some of which are integrated together
to facilitate the PCB design workflow, and some of which are standalone.  In early versions of
KiCad, there was very little integration between the software components.  For example, the
schematic editor (historically called Eeschema) and PCB editor (historically called PcbNew) were
separate applications that had no direct link, and to create a PCB based on a schematic, users had
to generate a netlist file in Eeschema and then read this netlist file in PcbNew.  In modern
versions of KiCad, the schematic and PCB editor are integrated into the KiCad project manager, and
using netlist files is no longer required.  Many tutorials still exist that refer to the old KiCad
workflow of separate applications and netlist files, so be sure to check the version being used
when looking at tutorials and other documentation.

The main KiCad components are usually started from the launcher buttons in the KiCad project
manager window.  These components include:

[cols="25%,75%",options="header",]
|===================================
|Component name|Description
|Schematic Editor |Create and edit schematics; simulate circuits with SPICE; generate BOM files
|Symbol Editor |Create and edit schematic symbols and manage symbol libraries
|PCB Editor |Create and edit PCBs; export 2D and 3D files; generate fabrication output files
|Footprint Editor |Create and edit PCB component footprints and manage footprint libraries
|GerbView |Gerber and drill file viewer
|Bitmap2Component |Convert bitmap images to symbols or footprints
|PCB Calculator |Calculator for components, track width, electrical spacing, color codes, etc.
|Page Layout Editor |Create and edit worksheet files
|===================================

[[ui-overview]]
=== User Interface

KiCad has a number of user interface behaviors that are common to all the different editor windows.
Some of these behaviors are described in more detail in later chapters of this manual.

Objects can be selected by clicking on them or by dragging a selection window around them. Dragging
from left to right will result in a selection of any items that are completely within the window.
Dragging from right to left will result in a selection of any items that touch the window. Pressing
certain modifier keys while clicking or dragging will change the selection behavior.  These keys
are platform-specific and are described in the Editing Options section of the Preferences dialog.

KiCad editors have the concept of a **tool** which can be thought of as a mode that the editor is
in.  The default tool is the selection tool, which means that clicking will select objects under
the mouse cursor as described above.  There are also tools for placing new objects, inspecting
existing objects, etc.  The active tool is highlighted in the toolbar, and the name of the active
tool is shown in the bottom right of the editor in the status bar.  Pressing **Esc** always means
"cancel" in KiCad: if a tool is in the middle of some action (for example, routing tracks), the
first press of **Esc** will cancel that action.  The next press of **Esc** will exit the tool
complely, returning to the default selection tool.  With the selection tool active, pressing
**Esc** will clear the current selection, if one exists.

[[projects-and-files]]
=== KiCad Projects and Files

NOTE: TODO: Write this section

- File types and project structure
- Project workflow
- Schematic <> PCB workflow
- Standalone vs. project mode for schematic and PCB editors

[[symbol-and-footprint-libraries]]
=== Symbol and Footprint Libraries

NOTE: TODO: Write this section

- Relationship between libraries and design files
- Global vs project libraries
- The KiCad library project (built-in global libraries)

[[accessory-tools]]
=== Accessory Tools

NOTE: TODO: Write this section

- GerbView
- PCB Calculator
- Bitmap2Component
- Worksheet Editor (pl_editor)


[[further-reading]]
== Further Reading

The latest version of this manual can be found in multiple languages at https://docs.kicad.org
Manuals for previous versions of KiCad can also be found at that website.

The KiCad user community includes a number of forums and chat platforms that are operated
independently from the KiCad development team but are fully endorsed as a great way to find help
with problems, learn tips and tricks, and share examples of KiCad projects.  A listing of
community resources is available under the Community heading at https://www.kicad.org

Users interested in compiling KiCad from source and/or contributing to KiCad development should
visit our developer documentation site at https://dev-docs.kicad.org for instructions, policies and
guidelines, and technical information about the KiCad codebase.
