Basic Eagle question about DIPs in schematics

Question

I just started using Eagle this morning, and I've read/watched some tutorials, but with no luck on this question; please forgive my naivete.

I want to insert an LM324 (quad op-amp) into a schematic. I want the schematic to show the DIP structure, not just four op-amps scattered around the diagram. (Why? Because right now I'm trying to trace a circuit board and turn it into a schematic, and having something that's laid out the way the chip is laid out will be a big help; once I've done that, I'll swap in the four individual op-amps and do some un-rat's-nesting.)

Is there a way to do this? The LM324 I found simply lets me click 5 times on the schematic, showing 4 op-amps and a power circuit (Vee to Vcc block).

Answer 1

You can make your own schematic symbol & layout footprint in eagle pretty easily, I have a set of slides I created a while ago that outline the process I follow.

http://www.crossroadsfencing.com/BobuinoRev17/eagleSymbol/Slide1.JPG http://www.crossroadsfencing.com/BobuinoRev17/eagleSymbol/Slide2.JPG http://www.crossroadsfencing.com/BobuinoRev17/eagleSymbol/Slide3.JPG http://www.crossroadsfencing.com/BobuinoRev17/eagleSymbol/Slide4.JPG http://www.crossroadsfencing.com/BobuinoRev17/eagleSymbol/Slide5.JPG http://www.crossroadsfencing.com/BobuinoRev17/eagleSymbol/Slide6.JPG http://www.crossroadsfencing.com/BobuinoRev17/eagleSymbol/Slide7.JPG http://www.crossroadsfencing.com/BobuinoRev17/eagleSymbol/Slide8.JPG

Answer 2

Ok, so I think part of the answer to your question lies in the fact that schematic view and board view in EAGLE have different purposes. The schematic view has the purpose of making the function of the circuit easy to understand, and the schematic should be laid out in such a way to serve this purpose. This is why when you place a chip like a quad op amp in schematic view, it will give you four op amp symbols and one power connector symbol (Once you've placed the op amps in your schematic, "invoke" one of them to get the power pins for the quad chip).

So in your schematic, disregard physical layout to some degree and concentrate on making the circuit visually easy to understand.

Once you have completed your schematic, you can switch to board view. You'll be presented with a mishmash pile of all of the physical objects you had in your schematic, all connected in the same way with thin yellow "airwires". At this point you probably have some idea of how things go physically, so I like to drag them far apart on the screen, spread out roughly the way I think makes sense, and then switch and move things around to simplify the airwires and reduce the amount they need to cross eachother. Then it's easy to cluster them back together in a nice pattern on the circuitboard.

If you're trying to copy an existing circuitboard, you can place the components on the schematic, connect what's obvious, but arrange things and keep arranging them so they make sense on the schematic as you go, then go to board view, arrange the physical components the same way as on the original board, and then just look at pin arrangements. "Ok Pin 3 on this IC is connected to capacitor c5", look what the pin is labeled on board view, then go back to the schematic, connect the appropriate line, rearrange the schematic if necessary, then switch back to board view and use the Route tool to put the trace where it would be on the original board, to show that it is done. Rinse, lather, repeat.

The schematic and board views each have a purpose, and especially if the board you're trying to reproduce is complex, trying to use the schematic as a makeshift board view could easily work against you in the end, especially when you have the actual board view readily available and automatically linked to the schematic.

Answer 3

It is common practice to break up symbols into sub-parts. Especially for "well-known" components like opamps and transistors with standard symbols.

In other cases its often done to separate functional areas of a component. For example, a micro-controller may have 200 pins and it can be a bit silly to have a single symbol with that many pins (often it is as large as the page itself). What is commonly done is to split the symbol into functional groups: power, gpio, clocks, etc. each one has its own symbol.

If you do not like this, then I would take the opportunity to create your own symbols, copy the existing library and modify the component to have only one symbol with 4 gates. I still recommend keeping the standard arangement for discrete components it is much harder to "read" the schematic when you have monolithic boxes instead of standard discrete symbols. Visually an opamp circuit is easy to glance at and get a basic understanding of it. But when you are learning it is convenient to forgo this to not get confused, and learning symbol creation is a more useful skill.

Eagle manages component subparts with one reference designator, with an optional number or letter sequence appended after each sub-part. When you go to layout the board the component will appear as one device. If you need a wiring diagram you can use tDocu layer to add notes to your PCB drawing. You can also edit the symbol to show the pin number on the schematic symbol.

Answer 4

For reverse engineering and debugging reasons, you can re-build the part with a different symbol.

For instance, here's something similar to what you're working with.

You can create your own symbol and map the pins to the same footprint. I quickly made a single symbol for the one above.

Once you're done debugging, you can revert back to the traditional symbols to clean up your schematic a bit.