EAGLE Style Guide

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Revision as of 23:20, 10 July 2020 by Asrinivasan77 (talk | contribs)
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Part Creation

Symbol

Grid

  • Size: 0.1 in
  • Alt: 0.01 in

Name

  • Should be manufacturer part/family number (eg. ATTINY167-SU)

Description

  • Leave blank

Style

  • Origin
    • Center origin (crosshair) on symbol center
  • Text
    • Keep text horizontal
    • Size: 0.07 in
    • Ratio: 8%
    • Line Distance: 50%
    • Font: proportional
  • Name
    • Locate in top left of symbol
    • Align: bottom-left
    • Layer: 95 Names
    • Value: >NAME
  • Value
    • Locate in bottom-left of symbol
    • Align: top-left
    • Layer: 96 Values
    • Value: >VALUE
  • Outline
    • Use Lines
      • Width: 0.01 in
      • Style: continuous
      • Layer: 94 Symbol
      • Curve: 0
    • Try to have a length/width that is a 0.1 in multiple (eg. 0.4 in by 0.4 in)

Functionality

  • Pins
    • Label pins to allow the symbol to be applied to parts in similar families
    • Name: Based on part datasheet
    • Direction: pas (passive)
    • Swap Level: 0
    • Length: middle
    • Function: none
    • Visible: both
  • Pin Placement
    • Power (VCC): top left
    • Ground (GND): bottom right
    • Inputs: left edge
    • Outputs: right edge
  • Passive Pins
    • Specifically resistors, capacitors, inductors, fuses, diodes
    • Visible: off
  • Connector Pins
    • Try to reuse an existing symbol for the size of connector
    • If need to make a new one, for pins:
      • Visible: pad
  • Decimal Labeling
    • For fractional values include the decimal point (eg. 3.3V, 4.5K)

Footprint

Grid

  • 1 mm Size
  • 0.1 mm Alt

Style

  • Center origin of grid on the center of the part
  • >VALUE tag aligned bottom-left
  • >NAME tag aligned top-left
  • Outline of package on tDocu/bDocu
  • Outline safe distance outside of package with tKeepout/bKeepout (width 0.1 mm) to prevent components from being placed on top of each other

Font

  • Font - Vector
  • Ratio - 10%
    • unless made bold for end user benefit
  • Size - 1 mm

Functionality

  • Silkscreen
    • Line for alignment on tPlace/bPlace
    • All ICs should have pin one marked with a dot
    • All diodes should have direction or cathode marks
    • Clearly indicate polarity as necessary
    • Try not to overlap pads with silkscreen; although tedious, cut a section out
  • Slots
    • Use the milling layer (46) to draw the outline of the slot
    • Create the pad using the elongated pad
    • Set the hole diameter to the width of the slot
    • Export the milling layer to its own gerber file and attach it with the rest of your gerbers
    • Every manufacturer has its own preferred method, but seems to be accepted widely enough

Device

Attributes

  • Name should be manufacturer part number
  • Attribute - DKPN should be filled with the Digi-Key part number

Descriptions

  • One sentence describes the function of the part
  • Datasheet link (if available)

Prefix

Chart for Designation
Letter Part Type
A Separable assembly or sub-assembly (e.g. printed circuit assembly)
C Capacitor
D Diode, LED
F Fuse
FB Ferrite bead
J Jack or Connector (least moveable connection part)
JP Jumper
K Relay or Contactor
L Inductor
LS/BZ Loudspeaker or Buzzer
M Motor
P Plug (most moveable connection part)
PS Power Supply
Q Transistor
R Resistor
RN Resistor Network
S Switch
T Transformer
TP Test Point
U Integrated Circuit
X Crystal

Schematics

Overall

  • Organize subsystems as follows:
  • Related subsystems should be grouped into a sheet
  • Each subsystem in a sheet should be boxed clearly, and that box labeled
    • Use line tool, width 0.006, shortdash, layer 97 info
    • Label font
      • Font - vector
      • Ratio - 12%
      • Size - 0.25 in
      • Layer - Info
    • Every sheet should have the following:
      • A frame no bigger than 11 x 17" (8½ x 11” preferred), which should have the following info:
      • A name
      • Last edit date
      • Last edit engineer(s)
      • Schematic version
      • Page #
    • Frames within a schematic should all be the same size

Nets

  • Every net should have a name if possible
    • Use xref tags at 0.05 size
  • Every bus should have a name and description
  • Every power net should be labeled with the acceptable voltage range and max current at the net driver
  • Differentially routed nets should be commented as such as the driver and sink
  • Impedance controlled nets should be commented as such as the driver and sink
  • Power and Ground nets
    • Use symbol with appropriate name

Configs

  • Any value computed (e.g. varies by application) from a datasheet should be noted
  • Any optional parts should be noted
  • 0ohm isolation resistor and 0ohm jumper resistors should be noted

Boards

Fab House / Validation

  • Load fab house DRC before place and route
  • RoboJackets has slightly conservative DRCs for 2 and 4 layer boards

Placement

  • Keep analog electronics far from high power electronics
  • Locate power net status LEDs near power sources
  • Provide adequate spacing for stitching/shielding if needed
  • Verify any mechanical considerations
    • Board mounting holes
    • Component mounting holes/cutouts
    • Use tDoc/bDoc and/or tKeepout/bKeepout for bolt head size to prevent traces near mounting
  • Place decoupling capacitors as close to the power pin of the IC as possible
    • Smallest values should be closest to pin to minimize parasitic inductance

Routing

  • Avoid minimum trace width where possible
    • Suggestions: 0.2 to 0.3mm for signals, 0.4 to 0.5mm for power (increase as needed for current rating)
  • Avoid minimum trace spacing where possible
  • Avoid minimum drill/via size where possible
    • Suggestions: 0.35mm drill, 0.65mm diameter for vias
  • Do not split differentially routed pairs unless impedance and arrival time can be matched
  • Avoid vias on signals above 1GHz
  • Use the same number of vias on differentially routed traces
  • For two layer boards, try to keep component, signal, and power on the top layer and ground return on the bottom layer
  • High frequency signals should have continuous low impedance return path directly beneath trace.
  • Keep high frequency signals isolated from other signals to minimize crosstalk
  • Route signals orthogonally to avoid cross-talk

Silkscreen

  • This is far more important than most people realize and can take a significant amount of time to get right. A good silkscreen makes a board easier to use, easier to debug, and harder to break.

Meta

  • Have at least a "vMAJOR.minor" version label on the board
  • Have your team name and year (optionally month, Ubuntu style) on the board
  • Have your team logo on the board
  • Have a filled white square to write in an instance ID
    • Recommended if more than three boards will be fabricated
    • e.g. can say "board #2 is broken", there is a "2" written on the white square
    • Cover ink with Kapton tape
  • Don’t place them on vias (even tented vias) unless absolutely unavoidable

Components & Connectors

  • Set default line width to 0.2mm
  • Label all power inputs with name and voltage (current optional)
  • Label all connectors with name
  • Label all switches with position values
  • Label all debug LEDs
  • Label all fuses with current rating (type optional)

Font

  • All font should be vector rendered
  • All font should be ratio 8%, unless made bold for end user benefit
  • Component font size should be "1"
    • e.g. R45, Q1, etc.
  • Layer - t/bPlace
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