Rules on Editing Schematics

Naming Values and Units

• For example, values would change as follows:

resistor: 1 MOhm -> 1M, 4.7 kOhm -> 4k7, 49.9 Ohm -> 49R9, 220 Ohm -> 220R, 20 mOhm -> 0R02
capacitor: 10 uF -> 10u, 3.3 uF -> 3u3, 100 nF -> 100n, 4.7 nF -> 4n7.
bead: current rating
varistor: Vdc or Vac

• error percentage

Power Symbols

• 

  Used by POWERED flag

Directions of Global/Local Labels

• 

  Right use case: global lable

• 

  Wrong use case: global lable

Style of Junctions

Use the right-side variant of 3a of http://en.wikipedia.org/wiki/File:Schematic_junctions.svg

Better Looking

http://downloads.qi-hardware.com/people/werner/tmp/style-0.pdf

Checklists of Symbols

1. is the symbol understandable ?
2. are all pins present ?
3. do they have the correct name ?
4. do they have the correct number ?
5. does the pin type correspond to what the data sheet says ?
6. is text large enough ? (0.050-0.060" for component reference and value(s), 0.050" for pins and other text)
7. more ?

Checklists of Schematics

1. are the styles of values the same ?
2. are things free from overlaps ?
3. is text readable ? (When adding a symbol from the component library to schematics, a copy is made of the fields. So if the text size is/was later changed in the library, this isn't automatically reflected in the schematics and the two may diverge.)
4. can text be unambiguously associated with components ?
5. are component references on top or the left of values and/or part numbers ?
6. are comments/explanations understandable ?
7. when wires join in a T, is there a junction mark ?
8. are there no junction marks anywhere else ? In particular, do we only have crossings of the types 2b, 3b, and the right side of 3a, but never 1a or 2a ?
9. are connections straight and clear ? Here are some style
  suggestions:
  http://downloads.qi-hardware.com/people/werner/tmp/style-0.pdf
10. do positive rails point up, ground (and negative rails, but we don't have that in M1) down wherever reasonable ?
11. do labels point in the direction of the signal ? (This is all wrong in the original M1 schematics.)
12. more ?

Links

• reviews (was Re: [Milkymist-devel] [KiCad M1R4] First KiCad version for Milkymist One Schematics.)
• International System of Units
• the beginning of the discussion thread of Values and units in schematics
• the conclusion of the discussion thread of Values and units in schematics
• the results of Values and units in schematics
• Schematic Junctions