Introduction

Often times some general EE terms are used and because we have newer members I wanted to create a document to clearly state how they should be used and what the industry standard definitions and best practices are. Clear communication is critical for proper coordination within our team. Please ask questions if you have concerns or questions. We can absolutely update this document if needed!

History

This lesson was learned in conversation in discord here.

This is intended to be used for 2024 system architecture 2024 System Architecture initially and has evolved further since.

Terminology

Nouns

IC
- one of two meannings
  - integrated circuit
    - a circuit in a single package
  - individual contributor
    - a single person working on a project
Requirements
- A list of stipulations that must be met by a system to be satisfactory
- from google: a thing that is compulsory; a necessary condition.
Guidelines
- from google: a general rule, principle, or piece of advice.
- A loose requirement that is much more general and is not necessary but recommended
Design
- A plan of how something should be fabricated or assembled
- From google: a plan or drawing produced to show the look and function or workings of a building, garment, or other object before it is built or made.
Assembly
- A collection of assembled components
Net
- A single electrical conductor
- A “net name” indicates the purpose or use case of said net
Pinout
- refers to which pins on a connector or pins on a component or colors of wires in a harness represent which electrical nets of a connector
- can be used in the context of a connector associated with a component or a harness
- generally this information is conveyed via a table or a schematic
Component list
- list of parts you’re going to use
  - general part numbers or brief component descriptions
- generally doesn't include:
  - quantity
  - details
  - exact part numbers
Populated
- refers to:
  - components in a PCBA
  - components in a system
- means the component is present physically
Depopulated
- means a component is not present physically
- for example:
  - “the case for the board is depopulated” means the board is not inside the case
  - “that component is depopulated on the PCBA” means the physicaly component is not placed on the footprint that is dedicated for it on the PCB
BOM
- pronounced as it sounds and not said by letters
- short for bill of materials
- includes for each schematic designator
  - precise manufacturer part numbers
    - or an indication that no part should be populated: i.e. DNP
  - quantities
  - configurations/alternatives (if applicable)
- Note that there does not need to be a BOM line item for every designator as items flagged as "generic no bom" (for example mounting holes) will not be included in the BOM even if they have a designator in the schematic.
Diagram
- blocks diagram
  - blocks represent components (shown with MPNs)
  - lines represent an electrical connection
    - without detail as to how that thing is connected, just saying its connected electrically
      - i.e. ambiguous as to RF link, cable link, or wire link
Cable
- a set of wires
- normally encased in insulation
Wire
- single piece of copper conductor, normally encased in insulation
Schematic
- components with designators with all of their exposed electrical conductors mapped to a pin
  - Components are generally referred to as “symbols” at this stage and all of their available interface exposed electrical conductors are referred to as “pins”.
  - generally MPNs or more descriptors are provided in the schematic though this is not required as this information is specified within the BOM
- lines represent single conducting wires (or chunks of copper for a PCB) between components.
Placement
- an indication of where every components in space is physically placed
  - for PCBs we generally consider this to be 2d
  - for systems (a collection of boards and mechanical housings) we consider this as 3d
  - Please note by definition placement requires knowing specific information about every component in a system, this requires knowing the components part numbers, and precise dimensions. Further, many component specific electrical guidelines may need to be recognized. This was discussed in some detail in this discord conversation.
- This does not include interconnects taking up space
Interconnects
- cables and wires in a system
- copper pours, planes, and traces in a PCB
Layout
- for systems layout is placement including the interconnects
- for PCBs layout is placement including all the copper interconnects defined within your schematic
- By definition a layout design necessitates having a placement design, though placement and layout are often performed in parallel by a designer because layout requirements influence placement.
- Note this also includes the pcb physical dimensions and any board cutouts, including drills such as vias and mounting holes.
Harness
- a cable (or set of cables) containing wires that connect components together.
Harness schematic
- diagram showing positions of each wire in a harness and how they connect to components electrical ports
- may specify requirements for wire:
  - colors
  - gauges
  - twisting
  - etc.
Harness layout
- indicates
  - materials
  - wire gauges
  - wire lengths
  - casings
  - insulations
  - their positions for a harness.
- Can be either done in a CAD or just have these parameters written out clearly
PCB
- printed circuit board
- bare board
- no components fitted
- a PCB design is defined by a PCB layout
Variant
- a specific list of component MPNs to be fitted in the corresponding to footprints on a PCB
- multiple variants correspond to a single pcb
- This definition was chosen to align with https://www.altium.com/documentation/altium-designer/design-variants .
- Variant Basics
PCBA
- printed circuit board assembly
- bare board with all of the components for a given variant soldered into it
System
- In a literal sense a system is something that takes input(s) and produces output(s)
  - this could be anything!
- From an EE perspective a system is where multiple boards and mechanical systems come together
- From a product perspective (which WARG generally uses) a system would be our entire drone and ground station setup.
Target System
- For a PCBA the target system is the system that the PCBA will be integrated into
MPN
- Manufacturer Part Number
(Power) Rail
- A constant current or constant voltage net
- Examples of specific rails: GND, 5V
Passive (Element)
- includes: resistors, capacitors, and inductors
- may include other components though is a bit ambiguous
- does not include: integrated circuits with digital logic, transistors

Verbs

Float
- generally refers to pins on an IC or connector
- means make the pin not electrically connected to anything
Pull High/Low
- means using a resistor (or anything more broadly) to pull a normally high impedance net to a certain state (normally GND or PWR)
- for example, I2C requires pullup resistors.
Design
- Creating a schematic or layout model in CAD or on paper for review or to help coordinate with others as to what you intend to do
Fabrication
- construction of a bare component
- PCB fabrication is fabricating the bare board
Assembly
- constructing a new larger more integrated component from a set of individual components
- PCBA assembly is assembling the bare board (PCB) and components together via soldering
- for a system this is assembling the PCBAs and harnesses into a vehicle.
Wiring
- an ambiguous term generally generally associated with assembly specifically in the context of assembling or connecting a harness
Manufacturing
- Fabrication and assembly

Related Resources

Glossary

Electrical

Electrical Terminology