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So I am working on a complex design that includes a BGA device with rather large number of pads that are grouped by functions (an ARM MCU and groups are MDIO, MMC, SERDES etc). This is my first project of doing such complex one, so forgive the lame question.

I've created a custom library device for this (since I could not find a ready device for this chip). And for this device I've created 1 symbol and 1 footprint.

I, of course, can work on schematics with this single symbol, but that is going to be a huge mess (~400 pins on this symbol).

I can see plenty of schematics (exported into PDF) show these are split into independent groups. Such as one schematics sheet would show everything power related and another for example everything MMC related (and symbols on each sheet would be that of only relevant pins of the chip). See attached pic below.

How do I achieve that in Eagle?

Additional question: I see in those schematics also that the whole design is split into blocks (i.e. as on attached picture with B2B_xxx connections) and the wire would resume on another sheet. How would I go about doing that?

Example schematics with modular MPU

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Simply create all of the smaller symbols that you want, and then in the device editor, simply add multiple symbols in the same way you would add a single one.

Eagle is quite happy for you to have multiple symbols for the same part. You can name each one in the device editor and that name will be suffixed to the name in the schematic.

For a simple example of this, have a look in the 40xx library (an Eagle default library). You can see how there are multiple gate symbols in the same device all connected to a single package.

When a part has multiple symbols, you can move the symbols around independently of each other, so can place them wherever you want in the schematic. You can also (assuming your license allows) use multiple sheets within your schematic and place different symbols in different sheets.

In your additional question, to split a trace across sheets, you draw a short wire connecting to the pin on the first sheet, then give that wire a name (the name of the net). You can also use the label tool to add a text label to the wire which automatically reflects any change to the net name.

On the second sheet, simply do the same thing. Any wires in a schematic with the same net name are considered connected.

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  • \$\begingroup\$ Thanks for the quick response. This means I can define multiple symbols and a single package for a device and then each symbol can go into a separate schematics file. Have I understood this correctly? Or should I still keep all of them in one schematics file? (also would highly appreciate if you could advice on the extra question). \$\endgroup\$
    – Alexey Kamenskiy
    Jan 13, 2018 at 8:26
  • \$\begingroup\$ @AlexKey you couldn't put each symbol in a different schematic file as Eagle cannot handle multiple schematics for the same PCB layout. You can however (assuming your license allows) use multiple sheets within your schematic and place different symbols in different sheets. You can also move the symbols around independently so can place them wherever you want in the schematic. \$\endgroup\$
    – Tom Carpenter
    Jan 13, 2018 at 8:32
  • \$\begingroup\$ Thanks! I will take that answer then and maybe a good idea would be to add that info to an answer. \$\endgroup\$
    – Alexey Kamenskiy
    Jan 13, 2018 at 8:36

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