Schematic drawing basics

[CarlG]

I think a blog about basic principles of schematic drawing could be interesting, and useful for many newbies. On the other hand, are there any universal "basic principles"? Surely there are lots of opinions about what a "good" schematic should look like For instance, is there a consensus about "signal flow left to right as default " as a general rule?

A schematic's most important goal is, as I see it, to define the electrical connections. Beside that, is think basic aims for the schematic includes making it possible to follow the signal flow rather easily, and give an understanding the function of the design. The two latter aims does of course not conflict with the first. However, I've seen examples of single sheet designs with no wires drawn between the functional parts, just "connected" by the node names. OK or not? What about a multisheet schematic without top level sheet?

Example of details that could be covered:
- making a symbol (e.g. placing I/Os)
- signal naming conventions
- connections conventions
- single/multisheet schematics
- multisheet: what function should come first?
- when is a design description needed?

Cheers

[free_electron]

Make custom symbols to avoid crossing lines
Multisheet is fine but clearly label signals going offsheet and what sheet they go to. If they go to multiple sheets ( like busses ) refer them to the toplevel and show the bus there.

Toplevel is first sheet. Toplevel should read like a block diagram.

Netnames do not leave sheets. Anything that leaves a sheet uses a port. Thats what those things are intended for.

Rearrange parts and pins to minimize crossings of wires. Use clear signal names on pins of components. Netnames should have a meaning.