basic documentation

psychogenic · Feb 4, 2024 · 9557e67 · 9557e67
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-# psychogenic-eeschema
-eeschema schematic manipulation
+# kicad skip: S-expression kicad file python parser
+
+Copyright &copy; 2024 Pat Deegan, [psychogenic.com](https://psychogenic.com/)
+
+
+This library is focused on scripted manipulations of schematics (and other) kicad  _source_ _files_  
+and allows any item to be edited in a hopefully intuitive way.
+
+It also provides helpers for common operations.
+
+
+Kicad schematic, layout and other files are stored as trees of s-expressions, like
+
+```
+(kicad_sch (version 20230121) (generator eeschema)
+  (uuid 20adca1d-43a1-4784-9682-8b7dd1c7d330)
+  (title_block (title "My Demo Board") (date "2024-01-31") (rev "1.0.5")
+    (company "Psychogenic Technologies") (comment 1 "(C) 2023, 2024 Pat Deegan")
+  )
+  (lib_symbols
+    (symbol "74xx:74CBTLV3257" (in_bom yes) (on_board yes)
+      (property "Reference" "U" (at 17.78 1.27 0) (effects (font (size 1.27 1.27))))
+      (property "Value" "74CBTLV3257" (at 15.24 -1.27 0)(effects (font (size 1.27 1.27))))
+  ...
+  (symbol (lib_id "SomeLib:Partname") (at 317.5 45.72 0) (unit 1)
+    (in_bom yes) (on_board yes) (dnp no)
+    (uuid 342c76f3-b2b8-40b2-a0b0-d83e480188cc)
+    (property "Reference" "J4" (at 311.15 29.21 0)(effects (font (size 1.27 1.27))))
+    (property "Value" "TT04_BREAKOUT_REVB" (at 317.5 76.2 0) (effects (font (size 1.27 1.27))))
+    (property "Footprint" "TinyTapeout:TT04_BREAKOUT_SMB" (at 320.04 81.28 0)
+    (effects (font (size 1.27 1.27)) hide))
+    (pin "A1" (uuid 5132b98d-ec39-4a2b-974d-c4d323ea43eb))
+    (pin "A10" (uuid bf1f9b27-0b93-4778-ac69-684e16bea09c))
+    (pin "A19" (uuid 43e3e4f6-008a-4ddf-a427-4414db85dcbb))
+  ...
+```
+which are great for machine parsing, but not so much for a quick scripted manipulation.
+
+With skip, you can quickly explore and modify the contents of a schematic (or, really, any
+kicad s-expression file).
+
+
+## Examples
+
+Effort has been made to make exploring the contents easy.  This means:
+
+#### named attributes 
+Where possible, collections have named attributes: **do use** TAB-completion, schem.<TAB><TAB> etc
+
+Examples
+
+```
+>>> schem.symbol.U TAB TAB
+```
+outputs (something like, depending on schematic):
+
+```
+  schem.symbol.U1          schem.symbol.U3          schem.symbol.U4_B        schem.symbol.U4_D               
+  schem.symbol.U2          schem.symbol.U4_A        schem.symbol.U4_C        schem.symbol.U4_E
+```
+
+and
+
+``` 
+>>> schem.symbol.U1.property. TAB TAB
+```
+
+outputs
+
+```
+ schem.symbol.U1.property.Characteristics           
+ schem.symbol.U1.property.Datasheet                  
+ schem.symbol.U1.property.DigikeyPN                  
+ schem.symbol.U1.property.Footprint                  
+ schem.symbol.U1.property.MPN                        
+ schem.symbol.U1.property.Reference                
+ schem.symbol.U1.property.Value    
+```
+
+#### representation
+`__repr__` and `__str__` overrides so you have an idea what you're looking at.  Just enter the variable in the REPL console and it should spit something sane out.
+
+
+```
+>>> schem
+<Schematic 'samp/my_schematic.kicad_sch'>
+
+>>> schem.symbol[23]
+<symbol C28>
+
+>>> schem.symbol[23].property
+<Collection [<PropertyString Reference = 'C28'>, <PropertyString Value = '100nF'>, 
+ <PropertyString Footprint = 'Capacitor_SMD:C_0402_1005Metric'>, 
+ <PropertyString Datasheet = '~'>, <PropertyString JLC = ''>, 
+ <PropertyString Part_number = ''>, <PropertyString MPN = 'CL05A104KA5NNNC'>, 
+ <PropertyString Characteristics = '100n 10% 25V XR 0402'>, 
+ <PropertyString MPN_ALT = 'GRM155R71E104KE14J'>]>
+
+>>> schem.wire[22]
+<Wire [314.96, 152.4] - [317.5, 152.4]>
+
+>>> schem.text[4]
+<text 'Options fo...'>
+
+# and much more, e.g. for library symbols, junctions, labels, whatever's in there 
+```
+
+
+## Quick walkthrough
+
+Here's some sample interaction with the library.  The basic functions allow you to view and edit attributes.  More involved helpers let you search and crawl the schematic to find things.
+
+
+#### basic
+
+```
+# load a schematic
+schem = skip.Schematic('samp/my_schem.kicad_sch')
+
+# loop over all components, treat collection as array
+for component in schem.symbol:
+    component # do something 
+
+# search through the symbols by reference or value, using regex or starts_with
+>>> schem.symbol.reference_matches(r'(C|R)2[158]')
+[<symbol C25>, <symbol C28>, <symbol R25>, <symbol C21>, <symbol R21>, <symbol R28>]
+
+>>> sorted(schem.symbol.value_startswith('10k'))
+[<symbol R12>, <symbol R30>, <symbol R31>, <symbol R32>, <symbol R33>, <symbol R42>, 
+ <symbol R43>, <symbol R44>, <symbol R45>, <symbol R46>, <symbol R47>, <symbol R48>, 
+ <symbol R8>, <symbol R9>]
+
+# or refer to components by name
+conn = schem.symbol.J15
+
+# symbols have attributes
+if not conn.in_bom:
+    conn.dnp = True 
+
+# and properties (things that can be named by user)
+for p in conn.property:
+    print(f'{p.name} = {p.value}')
+# will output "Reference = J15", "MPN = USB4500-03-0-A" etc
+
+# and change properties, of course
+>>> conn.property.MPN.value = 'ABC123'
+>>> conn.property.MPN
+<PropertyString MPN = 'ABC123'>
+
+
+
+# clone pretty much anything and modify it
+>>> mpn_alt = conn.property.MPN.clone()
+>>> mpn_alt.name = 'MPN_ALT'
+>>> mpn_alt.value = 'ABC456'
+
+
+# save the result
+>>> schem.write('/tmp/newfile.kicad_sch')
+
+# let's verify the change
+>>> schem.read('/tmp/newfile.kicad_sch')
+>>> conn = schem.symbol.J15
+>>> for p in conn.property:
+        p
+<PropertyString Reference = 'J15'>
+<PropertyString Value = 'USB4500-03-0-A_REVA'>
+<PropertyString MPN = 'ABC123'>
+<PropertyString MPN_ALT = 'ABC456'>
+
+```
+
+
+### Helpers
+
+Collections, and the source file object, have helpers to locate relevant elements.
+
+#### Attached elements
+
+Where applicable, such as for symbols (components), directly attached elements (via wires) 
+may be listed using attached_*
+
+```
+>>> conn = sch.symbol.J15
+
+>>> conn.attached_ TAB TAB
+ conn.attached_all            
+ conn.attached_global_labels  
+ conn.attached_labels         
+ conn.attached_symbols        
+ conn.attached_wires
+>>> conn.attached_symbols
+ [<symbol C3>, <symbol R16>, <symbol C47>, 
+  <symbol R20>, <symbol C46>, <symbol R21>, 
+  <symbol F1>]
+
+>>> conn.attached_labels
+ [<label CC2>, <label CC1>]
+ 
+# or list everything attached
+>>> conn.attached_all
+ [<symbol C3>, <symbol R16>, <symbol C47>, 
+  <symbol R20>, <symbol C46>, <symbol R21>, 
+  <symbol F1>, <global_label usb_d->, 
+  <global_label usb_d+>, <label CC2>, 
+  <label CC1>]
+
+```
+
+#### finding elements
+
+Symbols may be located by reference or value
+
+  *  schem.symbol.reference_matches(REGEX)
+
+  *  schem.symbol.reference_startswith(STR)
+
+In addition, containers with 'positionable' elements have
+
+  * within_circle(X, Y, RADIUS)
+
+  * within_rectangle(X1, Y1, X2, Y2)
+
+  * within_reach_of(ELEMENT, RADIUS) # circle around ELEMENT's position
+
+  * between_elements(ELEMENT1, ELEMENT2) # within rectangle formed by two elements
+
+A collection will only return results of it's own type (e.g. global_labels.within_circle() will only return global labels).
+
+To search the entire schematic, the same within* and between() methods exist on the source file object (the schem, here).
+This will return any label, global label or symbol with the constrained bounds.
+
+```
+
+>>> schem.global_label.between_elements(sch.symbol.C49, sch.symbol.R16)
+ [<global_label usb_d->, <global_label usb_d+>, 
+  <global_label usb_d+>, <global_label usb_d->]
+>>> 
+>>> schem.between_elements(sch.symbol.C49, sch.symbol.R16)
+ [<symbol C44>, <symbol #PWR0121>, <symbol J15>, 
+  <symbol C47>, <symbol #PWR0122>, <symbol D5>, <symbol C48>, 
+  <symbol C45>, <symbol #PWR021>, <symbol C49>, <symbol R20>, 
+  <symbol C46>, <symbol #FLG02>, <symbol F1>, <symbol C3>, 
+  <symbol R16>, <symbol R21>, <symbol D6>, <label CC2>, 
+  <label CC1>, <label vfused>, <global_label usb_d->, 
+  <global_label usb_d+>, <global_label usb_d+>, 
+  <global_label usb_d->]
+
+```
+
+## API
+
+Further documentation to come.  For now, use the above, load a schematic in a console, and explore what's available using TAB-/code-completion.
+
+The main thing to note is that the leaves of the tree usually have a ".value" that should be used to access the actual contents and, especially, for setting values.  Have fun.
+
+2024-04-04
+Pat Deegan 
+
+