PCBs

About

Central repository of all schematics and PCB design files.

Folder	Project	Project Code
ail	Accumulator Indicator Light Logic	ail
ail-led	Accumulator Indicator Light Led	ail-led
batak	Batak Game (non-car)	batak
break-light	Rear Break Light	break-light
bspd	Brake System Plausibility Device	bspd
can-node	Voltage Reader and Broadcaster	can-node
curr-amp	Current Sensor Amplifier	curr-amp
dash	Dashboard	dash
discharge	Discharge Relay Breakout	discharge
hv-sense	High Voltage Sense	hvs
latching	Latch Circuit	latching
loom*	Loom Design	loom
lvbms	Low Voltage Battery Management System	lvbms
precharge	Precharge Controller	precharge
segment	Segment	segment
telemetry	On-Car Telemetry	telemetry
test-rig	PCB Test / Demo Rig	test
top-level*	Full Car Schematic
trc	TSAC Relay Controller	trc
tsal	Tractive System Active Light	tsal
vcu	Vehicle Control Unit	vcu

We design our PCBs in KiCad (version 8+).

*Moved to https://github.com/sufst/loom

Version Control for KiCad Projects

Why?

• Revert individual changes.
• Document development history via commits and GitHub issues.
• Easily view previous versions of designs.
• Manage shared library of components.

Files

Files that should be in this repo, under version control:

• Project files (.kicad_pro).
• Schematic files (.kicad_sch).
• PCB files (.kicad_pcb).
• Custom footprints (.kicad_mod).
• Custom symbols (.kicad_sym).
• Footprint library tables (fp-lib-table).
• Symbol library tables (sym-lib-table).
• 3D models of components (.step files).
• Simulation code (e.g. .asc files from LTSpice).

Files that should never be in here:

• Exports such as BOMs, gerbers, netlists, renders, etc.
• Local project settings (.kicad_prl).
• Project backups (.zip files generated in <project name>-backups, .bak.bck-bak files).
• Cache files (fp-info-cache).

The .gitignore should prevent the addition of files we don't want to keep in here, but before you commit make sure to do a quick check of what is actually being added.

Shared Resources

The common folder is used for resources which can be shared across multiple projects. This includes:

• Images (images subdirectory).
• 3D models (step subdirectory).
• Custom symbols (sufst-lib.kicad_sym).
• Custom footprints (sufst-lib.pretty).
• SUFST standard sheet layout (sheet-layout.kicad_wks).

Note: Since projects were previously in their own individual repos, many designs still have their own libraries, step files, etc. These will gradually be migrated to the SUFST library.

Library Paths

When you configure the library paths for a project (sym-lib-table and fp-lib-table data), make sure to always use a path relative to the project with the ${KIPRJMOD} substitution.

• Correct: ${KIPRJMOD}/../common/sufst-lib.kicad_sym
• Incorrect: /Users/<your name>/Documents/sufst/pcb/common/sufst-lib.kicad_sym

If an absolute path is used, when someone else opens the project that path will not exist and the library paths will not be valid. -lib-table files should never contain an absolute path.

Git Limitations

It is not possible to resolve merge conflicts within individual design files, which is an unfortunate limitation of using git with KiCad. While KiCad files are in a text format, they aren't really designed to be edited manually. It is therefore essential that only one person is editing a particular file in a project at a time (including the shared library). Once someone starts working on a file, until it is merged into the main branch nobody else can edit that file. A good way to get round this is to use the "hierarchical sheets" feature to divide schematics into multiple files (if it can be done in a logical way).

Releases

Release Files

When a PCB is fabricated, a new 'release' for the given project should be created and stored within this repo in the releases/<PROJECT NAME> folder. This folder should contain the latest version (and ONLY the latest version) of the following files:

1. Exported gerbers and drill files in a ZIP archive called fabrication.zip.
2. Schematic sheets as a PDF (Schematic.pdf).
3. Layout as a PDF in colour, with border and title block (Layout.pdf).
4. HTML iBOM created using the "Interactive HTML BOM Plugin" (ibom.html).

Additionally, a file called info (no extension) should be created (if it doesn't already exist) containing release information in the following format:

version: <VERSION NUMBER>
date: <RELEASE DATE>
fabrication: <COMPANY>

Version numbers should be in the format v1.0.1 and dates should be in the format YYYY-MM-DD. For example:

version: v1.0.1
date: 2023-01-23
fabrication: JLCPCB

The release folder for a project should then have the following structure and file names:

<PROJECT NAME>
├── Layout.pdf
├── Schematic.pdf
├── fabrication.zip
├── ibom.html
└── info

When creating a new release, make sure to overwrite/replace all the existing files.

Release Tag

The release commit should then be tagged with the following command:

git tag <PROJECT CODE>-<VERSION_NUMBER>

Tagging should be done after merging to main! Example command:

git tag segment-v1.0.1

To push tags to GitHub:

git push --tags