How to create a circuit drawing that allows easy mapping for setting up a breadboard

Question

I've read the post Rules and guidelines for drawing good schematics and whilst it does contain a lot of useful information, it doesn't address my question about a drawing to be use for breadboards.

As I progress through learning EE (with help from the Arduino), I’m finding that creating circuit diagrams is becoming a little awkward, and I’m not sure what is the ‘right’ way of doing this to make it better/clearer.

I create circuit diagrams, then load up breadboards using the diagram as a guide, so a messy diagram is really unhelpful. (I am not planning on creating circuit boards at all at the moment. This is just a hobbyist/learning process, as I play with different circuits, components etc)

Basically, I’m coming up with instances where multiple ICs are creating a LOT of cross over wires making it incredibly difficult to trace things through or easily see what connects to what.

A simple example is trying to link up an 8x8 LED Array (1088BS) to a MAX7219 Led Driver chip. The Pin I/O of each device is not helpful, and just looks like spaghetti on my drawing when I connect everything together.

I’ve currently switched to drawing each IC multiple times, so I can see the I/O in the correct order from each side. In the following drawing, the top half and bottom half of the page each only detail 2 ICs each, although 6 are drawn. (this was drawn using Visio until I learnt the right way to do it in an EE design application)

If I drew this diagram, with the ICs side by side, and the pins in the correct place, as it would be on the breadboard, it would just be an unusable mess.

What is the ‘correct’ way of drawing this kind of design? And would the ‘correct’ way be more beneficial to me as a guide to laying out breadboards? (and later on vero-boards)

The more I think of it, the more I'm thinking that it may not be possible to achieve, and I should change my approach to the problem rather than creating yet another drawing.

Answer 1

A schematic and a wiring diagram are two different things, so don't try to make one drawing serve both purposes. Before you wire anything, you have to understand the circuit. That means starting with a schematic. This is where you arrange the drawing to do the best job possible of explaining the circuit. Don't even think about layout at this stage.

Once you have a schematic that represents the circuit you think you want, there are various ways to proceed. Usually a piece of software that understands the connections implied by the schematic will guide you thru placement and routing of a PCB.

However, you seem to want to wire up a breadboard instead. What I do when I want to test something on a breadboard is to start with the schematic as usual, then print that out and wire up the breadboard accordingly. I work thru it one connection at a time. The schematic shows you the pin numbers, which is what you need to wire up the connections. Circuits you can put on a breadboard are small, so doing the layout as you go along wiring it up is no big deal.

I suppose you could make some sort of wiring diagram from the schematic, but I've never bothered with that. It really isn't a problem in my experience. The important thing is to be able to see the circuit, which is what the schematic allows you to do. Perhaps you could mark off connections on the schematic as you make them on the breadboard, but I really don't see the point to a special dedicated wiring diagram for the breadboard.

The point of a breadboard is to allow for easy editing of the circuit. Having two diagrams to keep up to date with the changes will get unweildy fast. Crossing out and adding parts with a pencil on a schematic printout makes a mess after a while if the changes are major. Then you need to go back and update the schematic on the computer anyway. Having to update yet another diagram would be tedious and lead to confusion when the inevitable mismatches occur.

Answer 2

The correct answer is that you should have two diagrams: schematic and layout.

The schematic can arrange pins on the IC symbols in a way that makes logical sense, rather than representing the physical pinout. Draw "bundles" on the schematic to represent a single bus with less spaghetti. Use as much space as necessary to make clear what is going on.

Then construct a layout. I've no experience with trying to get a normal PCB layout tool to do something that would be useful in laying out a breadboard instead; maybe there is a specialised tool for this. The important thing is that the software should keep the physical connectivity up to date based on the schematic.