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Hierarchical or flat design?

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  • Hierarchical or flat design?


    I was wondering your opinion on hierarchical design vs flat designs in Altium?

    From the classes I see that you have an initial page with a block diagram, indicating page numbers for each block. Why not take it one step further and make it into a altium hierarchical schematic?

    I have seen such first page block diagram in other professional designs as well, and they are very useful initial understanding of a complex project. But it's usually a pasted image drawn somewhere else. The disadvantages I see are: it might make it a harder a possible transfer of EDA software and it may make a small amount of confusion for others which have not used such features in altium.

    Thanks, and I'm looking forward for your anwsers.
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  • #2
    arthur.benemann some people use it, some not.

    Some time ago I really liked idea of hierarchical schematic and re-using blocks. Then, I designed a project with over 50 pages of schematic using 3 level hierarchy and ..... everybody hated it. Here are some reasons why I do not use it:

    - difficult to follow signals in schematic (especially in printed documents)
    - it was time consuming to keep the block pages synchronized with schematic pages (I had too keep updating the blocks/ports/nets on the hierarchical pages)
    - I have seen mistakes in schematics on hierarchical levels

    BTW: We always include block diagram in schematic, so everybody can quickly understand how the things are connected together.

    However, there are some cases/projects when blocks are useful. For example, I have seen a lot of FPGA designs done through hierarchy and re-using existing blocks.


    • #3
      For anything bigger than 10-15 pages and especially when the design itself has kind of a "hierarchical" structure, I tend to use hierarchical design in Altium. It just keeps the things well organized and grouped in logical blocks. For me it is also easier this way to track signals between the modules, etc. For some cases, if you need to do a multi-channel design for example, you are almost required to use a hierarchical design (might be possible without I guess, but won't feel as natural).

      Robert is right about the drawbacks of the hierarchical design though. Apart from the already listed ones, to me it's quite annoying sometimes to deal with local power nets for each sheet and need to pass all power nets and grounds around, using ports.


      • #4
        Thank you both for your insight.

        For me the hierarchical designs are mainly for making the structure more apparent, without interest in block reuse ( as you can easily copy&paste, and in both cases a net check is required). It looks that, as mairomaster said, the multichannel design is one of the places where it might have some advantages.