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A Python package for textually describing electronic circuit schematics.

Project description

The SKiDL Python package lets you compactly describe the interconnection of electronic circuits and components. The resulting Python program performs electrical rules checking for common mistakes and outputs a netlist that serves as input to a PCB layout tool.


  • Has a powerful, flexible syntax (because it is Python).

  • Permits compact descriptions of electronic circuits (think about not tracing signals through a multi-page schematic).

  • Allows textual descriptions of electronic circuits (think about using diff and git for circuits).

  • Performs electrical rules checking (ERC) for common mistakes (e.g., unconnected device I/O pins).

  • Supports linear / hierarchical / mixed descriptions of electronic designs.

  • Fosters design reuse (think about using PyPi and Github to distribute electronic designs).

  • Makes possible the creation of smart circuit modules whose behavior / structure are changed parametrically (think about filters whose component values are automatically adjusted based on your desired cutoff frequency).

  • Can work with any ECAD tool (only two methods are needed: one for reading the part libraries and another for outputing the correct netlist format).

  • Can perform SPICE simulations (Python 3 only).

  • Takes advantage of all the benefits of the Python ecosystem (because it is Python).

As a very simple example (see more in the blog), the SKiDL program below describes a two-input AND gate built from discrete transistors:
from skidl import *

# Create part templates.
q = Part("Device", "Q_PNP_CBE", dest=TEMPLATE)
r = Part("Device", "R", dest=TEMPLATE)

# Create nets.
gnd, vcc = Net("GND"), Net("VCC")
a, b, a_and_b = Net("A"), Net("B"), Net("A_AND_B")

# Instantiate parts.
gndt = Part("power", "GND")             # Ground terminal.
vcct = Part("power", "VCC")             # Power terminal.
q1, q2 = q(2)                           # Two transistors.
r1, r2, r3, r4, r5 = r(5, value="10K")  # Five 10K resistors.

# Make connections between parts.
a & r1 & q1["B C"] & r4 & q2["B C"] & a_and_b & r5 & gnd
b & r2 & q1["B"]
q1["C"] & r3 & gnd
vcc += q1["E"], q2["E"], vcct
gnd += gndt


And this is the output that can be fed to a program like KiCad’s PCBNEW to create the physical PCB:

(export (version D)
    (source "/media/devb/Main/devbisme/KiCad/tools/skidl/skidl/")
    (date "05/11/2021 10:40 AM")
    (tool "SKiDL (1.0.0)"))
    (comp (ref #PWR1)
      (value GND)
      (footprint "No Footprint")
        (field (name F0) #PWR)
        (field (name F1) GND))
      (libsource (lib power) (part GND))
      (sheetpath (names /top/16948080335112909674) (tstamps /top/16948080335112909674)))
    (comp (ref #PWR2)
      (value VCC)
      (footprint "No Footprint")
        (field (name F0) #PWR)
        (field (name F1) VCC))
      (libsource (lib power) (part VCC))
      (sheetpath (names /top/10777333099431236833) (tstamps /top/10777333099431236833)))
    (comp (ref Q1)
      (value Q_PNP_CBE)
      (footprint "No Footprint")
        (field (name F0) Q)
        (field (name F1) Q_PNP_CBE))
      (libsource (lib Device) (part Q_PNP_CBE))
      (sheetpath (names /top/5605641708446153824) (tstamps /top/5605641708446153824)))
    (comp (ref Q2)
      (value Q_PNP_CBE)
      (footprint "No Footprint")
        (field (name F0) Q)
        (field (name F1) Q_PNP_CBE))
      (libsource (lib Device) (part Q_PNP_CBE))
      (sheetpath (names /top/3991298653620578089) (tstamps /top/3991298653620578089)))
    (comp (ref R1)
      (value 10K)
      (footprint "No Footprint")
        (field (name F0) R)
        (field (name F1) R))
      (libsource (lib Device) (part R))
      (sheetpath (names /top/17650585640079795295) (tstamps /top/17650585640079795295)))
    (comp (ref R2)
      (value 10K)
      (footprint "No Footprint")
        (field (name F0) R)
        (field (name F1) R))
      (libsource (lib Device) (part R))
      (sheetpath (names /top/11461493733231665754) (tstamps /top/11461493733231665754)))
    (comp (ref R3)
      (value 10K)
      (footprint "No Footprint")
        (field (name F0) R)
        (field (name F1) R))
      (libsource (lib Device) (part R))
      (sheetpath (names /top/1249286041592970488) (tstamps /top/1249286041592970488)))
    (comp (ref R4)
      (value 10K)
      (footprint "No Footprint")
        (field (name F0) R)
        (field (name F1) R))
      (libsource (lib Device) (part R))
      (sheetpath (names /top/7242640812520981502) (tstamps /top/7242640812520981502)))
    (comp (ref R5)
      (value 10K)
      (footprint "No Footprint")
        (field (name F0) R)
        (field (name F1) R))
      (libsource (lib Device) (part R))
      (sheetpath (names /top/9932266607871614386) (tstamps /top/9932266607871614386))))
    (net (code 1) (name A)
      (node (ref R1) (pin 1)))
    (net (code 2) (name A_AND_B)
      (node (ref Q2) (pin 1))
      (node (ref R5) (pin 1)))
    (net (code 3) (name B)
      (node (ref R2) (pin 1)))
    (net (code 4) (name GND)
      (node (ref #PWR1) (pin 1))
      (node (ref R3) (pin 2))
      (node (ref R5) (pin 2)))
    (net (code 5) (name N$1)
      (node (ref Q1) (pin 2))
      (node (ref R1) (pin 2))
      (node (ref R2) (pin 2)))
    (net (code 6) (name N$2)
      (node (ref Q1) (pin 1))
      (node (ref R3) (pin 1))
      (node (ref R4) (pin 1)))
    (net (code 7) (name N$3)
      (node (ref Q2) (pin 2))
      (node (ref R4) (pin 2)))
    (net (code 8) (name VCC)
      (node (ref #PWR2) (pin 1))
      (node (ref Q1) (pin 3))
      (node (ref Q2) (pin 3))))


1.2.1 (2023-07-26)

  • is_url function fixed to solve problems with search and loading libraries.

1.2.0 (2023-07-14)

  • Added ability to generate an editable schematic from a Circuit object. (Currently only works for KiCad V5.)

  • Added Group object for creating hierarchy without using function calls.

  • generate_pcb now takes an optional list of footprint library directories.

  • If not explicitly declared, Part objects will load the default footprint from their symbol definition.

  • Added empty_footprint_handler() for parts without footprints that logs errors by default but can be overriden by the user.

  • Symbol libraries can now be searched on remote repositories by placing the URL in the lib_search_paths dictionary. KiCad V6 symbols are found at and V5 symbols are at

  • Part pins can now be sorted and retrieved in order using the ordered_pins property.

1.1.0 (2021-10-22)

  • Added generate_pcb() function to create a PCB file directly from a Circuit object. (Currently only works for KiCad.)

  • Added PartTmplt shortcut which creates a Part template using dest=TEMPLATE implicitly.

1.0.0 (2021-05-09)

  • Buses can now be created without names and a name will be automatically assigned. Or use “name=…” to manually assign a name. Or just place a string in the list of arguments and that will be used.

  • Footprint search can now process directories of footprints without the need for an fp-lib-table file.

  • Part fields can now be accessed using attributes.

  • Creating fields requires use of Part.fields[key] instead of Part.key.

  • Added context manager for Circuit object so Parts/Nets can be joined using a with… statement.

  • Adding/removing Parts to/from a Circuit can now be done using += and -=.

  • Tags can be added to Parts and Circuits for hierarchical naming.

  • Part values can now be assigned arbitrary objects including units from either PySpice or Pint.

  • Multi-function pin names can now be split into a collection of shorter aliases, thus reducing the need to access pins using regexes.

  • Schematics can now be automatically using the KiCad symbol graphics for the parts.

  • The library interface now handles the Skywater 130 SPICE libraries.

0.0.30 (2020-05-16)

  • Added @package decorator to make subcircuits act like Parts.

  • Interfaces now act like dictionaries so the ** operator works as expected.

  • Interface I/O can now be accessed using brackets ([]) and via attributes (e.g., intfc.a).

  • Interface I/O can now be assigned aliases.

  • Added tee() function for creating T-junctions in networks.

  • Custom ERCs can now be added using the erc_assert function.

  • Aliases take precedence over default pin names.

  • Substring matching in pin names can be enabled/disabled (off by default).

0.0.29 (2020-01-30)

  • Added XSPICE parts capability to SPICE simulations.

  • Unconnected XSPICE ports now are set to NULL in SPICE node lists.

  • Added no_files() function to disable output to files of netlists, ERCs, logs, backup libs.

0.0.28 (2019-12-17)

  • The zyc utility was split into a separate repository and placed on PyPi.

  • Fixed slicing of grouped part pins so things like ram['A[1]'] won’t grab A1, A10, A11, etc.

0.0.27 (2019-12-16)

  • Prevent changing the name of net 0 when generating a SPICE netlist.

  • Fixed Pin, Net, Bus and Part iterators so they’ll work in nested loops.

  • Part units are automatically added when a part is parsed.

  • Files are now opened for reading using latin_1 encoding to allow special symbols used by KiCad.

  • Part pins can now be aliased directly, e.g. uc[5].aliases += ‘gp0’.

  • Added class method get() to Part to allow finding a part based on name, reference, description.

  • Refactored ERC functions to allow user-extensibility.

  • Created a base object for Circuit, Part, Pin, Net, and Bus objects.

  • Added an aliases property to the SKiDL base object so all its children could be aliased.

  • Updated to perform simulations with ngspice version 30.

  • Added a notes property to allow attachment of user notes to Parts, Pins, Nets, etc.

  • Added net class to net objects for specifying net-specific design rules in PCBNEW.

  • Ignore multiple pins with the same number in symbols with DeMorgan equivalents.

  • Fixed problem with non-ASCII chars (e.g. Ohms) in strings.

  • Sped-up part/net naming using heap/cache, binary search, sets.

  • Sped-up by storing net traversals to avoid recomputation.

  • Fixed processing of slices in things like sdram[‘A[0:15]’].

  • Sped-up part_search() by eliminating unnecessary part parsing.

  • Improved schematic generation with graphviz.

  • Search now allows AND/OR of parenthesized terms.

  • New GUI for searching for parts and footprints.

  • Footprint libraries to search are now selected from the global fp-lib-table file.

  • KiCad library component field values are now stored in a dict in Part indexed by the field name or F0, F1, F2…

  • KiCad library component field values are also stored as Part attributes using the field name or F0, F1, F2…

  • Added p and n attributes to Part object to permit explicit reference to pin numbers or names.

0.0.26 (2019-01-25)

  • search command no longer looks in backup library because that leads to erroneous hits in all libraries.

  • Part objects will now iterate through their pins and len() will return the number of pins.

  • Updated netlist_to_skidl utility to account for new version of kinparse.

0.0.25 (2018-12-30)

  • Updated website.

  • KISYSMOD is no longer used to find part libraries, only KICAD_SYMBOL_DIR is used now.

0.0.24 (2018-09-15)

  • Fixed an error where creating a backup part library for a design would create extra pins attached to the nets.

0.0.23 (2018-08-25)

  • Added Network objects to make it easy to create serial & parallel combinations of two-pin parts.

  • SKiDL design hierarchy is now embedded in the KiCad netlist that’s generated.

0.0.22 (2018-05-XX)

  • Added Interface objects for storing complicated sets of I/O signals for subsystems.

  • ERC no longer redundantly checks every segment of a multi-segment net and reports multiple errors.

  • copy() function of Part, Bus, Pin, Net objects now returns a scalar object while copy(1) returns a list with one object.

  • Bus, Pin, and Net objects now have iterators.

  • Corrected initialization of KiCad library search paths.

0.0.21 (2018-04-30)

  • Added pull() and fetch() methods for getting/creating existing/new Net and Bus objects.

  • Added drive property to pins to override their default pin function attribute.

  • Part pins and units can now be accessed as attributes.

  • Nets, pins, and buses now support the width property.

  • Indexing with brackets now works equivalently for pins, nets, and buses.

  • Grouped part pins (such as address and data buses) can now be accessed using a slice-like notation, e.g. memory[‘ADDR[0:7]’].

0.0.20 (2018-03-08)

  • Matching of pin lists now begins with normal string matching before using regexes.

  • Added more tests and fixed existing tests.

0.0.19 (2018-02-20)

  • Selecting part pins now looks for exact match before falling back to regex matching.

  • PySpice now needs to be manually installed to perform SPICE simulations.

  • SPICE simulations of subcircuits (.SUBCKT) now supported.

  • Improvements/additions to the library of supported SPICE parts.

0.0.18 (2018-02-07)

  • SPICE simulations of circuits now supported (Python 3 only).

0.0.17 (2018-01-23)

  • Modularized code into separate files.

0.0.16 (2018-01-16)

  • Parsing of KiCad EESchema libraries made more robust.

  • DEFAULT_TOOL replaced with set_default_tool() function.

  • Some code simplification by using a context manager for opening files.

0.0.15 (2018-01-09)

  • Testing made more robust.

0.0.14 (2018-01-05)

  • KiCad netlists are now parsed using the external package kinparse.

  • Cleaned-up pylint-identified issues.

  • Removed absolute file paths to libraries from tests.

0.0.13 (2017-08-20)

  • Fixed problem where the search function was only returning parts found in the last library searched.

0.0.12 (2017-04-20)

  • Use of builtin now works with Python 2 & 3.

  • Started using namedtuple in some places (like net traversal) for clarity.

  • Corrected pin-to-pin connections so if a net is created, it goes into the same Circuit the pins are members of.

  • Part templates can now contain a reference to a Circuit object that will be applied when the template is instantiated.

  • When pins are connected to nets, or nets to nets, the resulting set of connected nets are all given the same name.

  • Buses are not added to a Circuit object if they are already members of it. This fix caused the next problem.

  • Buses weren’t getting added to the Circuit object because they already contained a reference to the Circuit. Fixed by clearing ref before adding to Circuit.

  • Created mini_reset() method to clear circuitry without clearing library cache so the libraries don’t have to be loaded again (slow).

  • search() utility now prints the names of libraries as they are searched so user sees progress.

  • Fixed exceptions if part definition contained non-unicode stuff.

  • Hide exceptions that occur when using the show() utility.

  • More tests added for NC nets and hand-crafted parts.

  • default_circuit and the NC net for the active circuit are now made accessible in all modules using __builtin__.

  • Corrected error messages that referenced wrong/non-existing variable.

  • Inserted NO_LIB for the library if it doesn’t exist when generating KiCad netlists or XML.

  • Attributes can now be passed when creating a Circuit object.

  • Pins are now associated with part when added to the part.

  • Minimum and maximum pins for a part are now computed as needed.

  • Each Circuit object now has its own NC net.

  • Added tests for bus movement and copying.

  • Implemented bus movement between Circuit objects.

  • Additional test cases were created.

  • Nets and Parts can now be removed from Circuits.

  • The circuit that pins and nets are in is now checked before connections are made so cross-circuit connections are not created.

  • Default members were added to Pin and Part objects so they would always exist and not cause errors when missing.

  • Implemented moving Parts and Nets from one circuit to another (almost).

  • Nets with no attached pins are now added to a circuit.

  • Re-wrote some tests to account for the presence of no-pin nets in a circuit.

  • A class method was missing its ‘self’ argument.

  • Fixed @subcircuit decorator so it won’t cause an error if the function it decorates doesn’t have a ‘circuit’ keyword argument.

  • Split the unit tests across multiple files. Added setup/teardown code.

  • Added capability to create multiple, independent Circuit objects to which Parts and Nets can be assigned. The default circuit is still the target if not Circuit is explicitly referenced.

  • Added IOError to exception list for opening a SKiDL part library.

0.0.11 (2017-04-04)

  • Part libraries in SKiDL format are now supported.

  • Parts can now be created on-the-fly and instantiated or added to libraries.

  • The parts used in a circuit can be stored in a backup SKiDL library and used if the original libraries are missing.

  • The KiCad standard part libraries were converted to SKiDL libraries and placed in skidl.libs.

0.0.10 (2017-03-13)

  • Nets without pins can now be merged.

  • Parts and Pins are now sorted when netlists are generated.

  • For an existing Bus, new bus lines can be inserted at any position or the bus can be extended.

0.0.9 (2017-02-16)

  • Use getattr() instead of __class__.__dict__ so that subclasses of SKiDL objects can find attributes named within strings without searching the __mor__.

0.0.8 (2017-01-11)

  • skidl_to_netlist now uses templates.

  • Default operation of search() is now less exacting.

  • Traceback is now suppressed if show() is passed a part name not in a library.

0.0.7 (2016-09-11)

  • Lack of KISYSMOD environment variable no longer causes an exception.

  • requirements.txt file now references the requirements from

  • Changed setup so it generates a pckg_info file with version, author, email.

0.0.6 (2016-09-10)

  • Fixed error caused when trying to find script name when SKiDL is run in interactive mode.

  • Silenced errors/warnings when loading KiCad part description (.dcm) files.

0.0.5 (2016-09-07)

  • SKiDL now searches for parts with a user-configurable list of library search paths.

  • Part descriptions and keywords are now loaded from the .dcm file associated with a .lib file.

0.0.4 (2016-08-27)

  • SKiDL scripts can now output netlists in XML format.

0.0.3 (2016-08-25)

  • Added command-line utility to convert netlists into SKiDL programs.

0.0.2 (2016-08-17)

  • Changed the link to the documentation.

0.0.1 (2016-08-16)

  • First release on PyPI.

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