python-eda

Python EDA tools (initially gEDA/gaf and Lepton EDA)

Build

python build.py my_output_dir_symbols my_output_dir_footprints

Where,

• my_output_dir_symbols is in the geda gafrc file
• my_output_dir_footprints is in the geda pcb .prj file

Folder usage

• footprints/fp/ - for manually crafted *.fp files
• footprints/gen/ - for mk_*.py generators (used to auto generate *.fp files)
• symbols/sym/ - for manually crafted *.sym files
• symbols/tsv/ - for *.tsv files (used to auto generate *.sym files)

Goal

Try to standardise fp gen's to:

• DIODE_* - diodes
• IND_* - inductors
• CAP_* - caps
• CONN_* - connectors (created by fp generators mk_CONN*.py)
• CONN_USB_* - USB connectors
• LED_* - LEDs
• RADIAL_* - THT parts (created by fp generator mk_RADIAL*.py)

Current Footprint Generators:

Should always be postfixed with "-N.py"

SMT: mk_QFN-N.py, mk_WFDFN-N.py, mk_SOIC-N.py, mk_SSOP-N.py, mk_TSSOP-N.py, mk_HTSSOP-N.py, mk_WSOP-N.py, mk_BGA-N.py, mk_uSIP-N.py, mk_pe*.py

THT: mk_CONN*.py, mk_RADIAL*.py, mk_holes.py

To Do List - up for discussion

1. fp gen - Support for arrays of pins/pads - should be able to do a whole row in one function call
2. fp gen - REFDES text and better positioning of REFDES text - better footprint metadata
3. fp gen - Support for two-way and four-way symmetrical arrays of pins and pads
4. w/x vs l/h/y definition/clarification - perhaps vertical/horizontal or stick with x/y standard coordinated frame: x = left/right, y = up/down
5. .sym generator (replacing .tsv) - particular for families
6. .sym to match manufacturer part number - likely the high level .sym generator should produce all names in the family
7. Check hole sizes - seems tight
8. Produce ruler for checking footprints
9. Add comment to link datasheet (to clarify dimensions)
10. Should connectors show the minimal outline and maximum outline (e.g. plug) - or perhaps two different footprints depending on size objectives
11. Enforce 80 char line limit?
12. Increase pin clearance suitable for pcbway design rules
13. Ensure footprints pads are larger then part pads
14. Ensure sch part pin spacing is 500
15. Ensure CONN 0,0 is at pin 1
16. Prefix SMT CAPs with CAP_SMT
17. Remove old radials scripts and use mk_RADIAL.py only
18. Cleanup usb sym's - pin number depends on USB version and connector type.
19. ensure bom created can handle part names with ,

gEDA/gaf and LeptonEDA built-in footprints

Under Linux:

$ find /usr/share/pcb/ -name "*.fp" | wc -l

1357

Below is a list of improvements to some key footprints:

• The built-in TO220/TO22OS/TO220SW/TO220W is the common 3-pin
• The built-in TO220ACSTAND/TO220ACS is the common 2-pin, we offer a better name:
  • TO220_2 - 2-pin
• The built-in TO247 and TO247_2 is the common 3-pin and 2-pin THT, we offer others:
  • TO247_GCE - GCE 3-pin
• The built-in TO263 is common 3-pin + tab SMT, we offer a few others:
  • TO263_GSD - GSD 3-pin + tab
  • TO263_2 - 2-pin + tab
  • TO263_7 - 7-pin + tab
• The built-in SOT23/SOT23D is the common 3-pin SMT, we offer:
  • SOT23_3 - 3-pin versoin
  • SOT23_BCE - BCE 3-pin version
  • SOT23_GSD - GSD 3-pin version
  • SOT23_5 - 5-pin version
  • SOT23_6 - 6-pin version

Footprint Naming Cross-Reference

Through-hole power packages

Our Footprint	JEDEC / Std Name	Common Aliases	Notes
TO220_2	TO-220-2 (JEDEC MO-036, MO-093)	TO-220AB, I-PAK (2 leads)	Regulators, diodes
TO247_GCE	TO-247AD (JEDEC MO-247)	TO-3P (vendor), G–C–E (IGBT)	High-power BJT/IGBT

Surface-mount power packages (DPAK / D2PAK)

Our Footprint	Package / JEDEC Outline	Common Aliases	Notes
TO252_3	TO-252 (DPAK)	“TO-252-3 (2 leads + tab)”	Diodes (anode, cathode, tab = cathode)
TO252_GSD	TO-252 (DPAK)	DPAK-3, SMD-220	MOSFETs (G–S–D, tab = D)
TO263_2	TO-263-2 (D2PAK, MO-169)	D2PAK-2, SMD-220 large	Diodes, 2 leads + tab
TO263_3 / TO263_GSD	TO-263-3 (D2PAK, MO-169)	D2PAK-3	MOSFETs, tab = D
TO263_7	TO-263-7 (D2PAK, MO-169)	D2PAK-7	Multi-lead regulators, drivers

Naming note (TO-252): We follow distributor/JEDEC terminal count for diodes:

• TO252_3 = “2 leads + tab” - for diodes like symbols/sym/DIODE_TO252_3.sym
• For TO-263 we keep the more common lead-count style (TO263_2, TO263_7).

Small-signal transistor packages

Our Footprint	JEDEC / Std Name	Common Aliases	Notes
SOT23_3	TO-236AB (JEDEC MO-178)	SOT-23-3, SC-59	Generic 3-pin
SOT23_BCE	TO-236AB	SOT-23 (BCE pinout)	Bipolar transistors
SOT23_GSD	TO-236AB	SOT-23 (GSD pinout)	MOSFETs
SOT23_5	JEDEC MO-178 (variant)	SOT-23-5, SC-74	Regulators, op-amps
SOT23_6	JEDEC MO-178 (variant)	SOT-23-6, SC-74A	Analog switches, FET arrays
SOT416_3	JEDEC MO-193 (variant)	SOT-416, SC-75	3-pin numbering (BJTs)
SOT416_GSD	JEDEC MO-193 (variant)	SOT-416, SC-73	MOSFET G-S-D mapping

Surface-mount diode / TVS packages

Our Footprint	JEDEC / Std Name	Common Aliases	Notes
DIODE_SMA	DO-214AC	SMA, SMAJ (TVS)	~4.3 × 2.5 mm
DIODE_SMB	DO-214AA	SMB, SMBJ (TVS)	~4.6 × 3.6 mm
DIODE_SMC	DO-214AB	SMC, SMCJ (TVS)	~7.0 × 6.2 mm
DIODE_SOD123	—	SOD-123	~2.7 × 1.6 mm
DIODE_SOD123F	DO-219AB	SOD-123FL, SOD-123F, SMF	Flat-lead TVS form factor
DIODE_SOD323	MO-567	SOD-323, SC-90	2.5 × 1.25 mm
DIODE_SOD923	MO-254	SOD-923	Ultra-mini (1.0 × 0.6 mm)

Key takeaways

• TO-252 / TO-263:
  • TO252_3 = diode (2 leads + tab), by distributor convention.
  • TO252_GSD = MOSFET (3 leads + tab).
  • TO263_2, TO263_3, TO263_7 follow lead-count style.
• SOT / SC naming:
  • SC-59 = SOT-23-3
  • SC-74 = SOT-23-5
  • SC-74A = SOT-23-6
  • SC-73 / SC-75 = SOT-416
• DO / SOD families:
  • SMA = DO-214AC
  • SMB = DO-214AA
  • SMC = DO-214AB
  • SOD-123F = DO-219AB (SMF)
  • SOD-323 = MO-567
  • SOD-923 = MO-254