PCB software

Discussion in 'General Electronics Chat' started by freddurst, Mar 12, 2014.

  1. freddurst

    Thread Starter New Member

    Aug 1, 2013
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    Can someone tell me which is the best pcb software that auto calculates the shortest route between components leads from a schematic for trace making in order to make the circuit as compact as possible
     
  2. pwdixon

    Member

    Oct 11, 2012
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    The only way this could be answered is if you managed to find an auto-placing auto-routing optimising pcb layout package and I'm not sure that even exists. Normally one has to layout the components on the board and route the traces. That means the shortest traces will be defined by component positioning. I have seen auto-placement in Eagle but that was simply placing the parts I'm pretty sure there was no optimisation of placements.
     
  3. t06afre

    AAC Fanatic!

    May 11, 2009
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    Yes and no. Most ECAD tools do have both autoplacement and autorouter options. I find the most of autoplacement tools unmitigated useless compared to a human. The autorouter in most cases works. But again an experienced human can often do better. Creating a PCB is a quite dynamic process. Then I create a PCB. I often find the need to go back to the schematic and do changes. Like swop around the order then using components with many similar functions say a 4 OPAMP IC
     
  4. freddurst

    Thread Starter New Member

    Aug 1, 2013
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    Yes but if u have already made all the possible changes & u have somewhat of a static design & u just want the program to auto make the traces.
    Anyone else might know of some other program?
     
  5. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    most PCB programs have an autorouter and they all attempt the "cleanest" routing they can. some are better than others though.
    You are going to have to be very specific about exactly what you expect this program to do if you want specific answers.
    I like Diptrace.
    Its autorouter is decent and you can use a 3rd party router if its not sufficient. And personally I find diptrace far easier to use/learn than Eagle..
     
  6. GRNDPNDR

    Member

    Mar 1, 2012
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    Don't know if you can afford it, but multisim comes with ultiboard and I personally really like it. Once you do the design in multiim it will export it to ultiboard which then has an autoroute/place feature.
     
  7. John P

    AAC Fanatic!

    Oct 14, 2008
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    The one I use is FreePCB, and I think it works very well--without any size restrictions as with Eagle. It's capable of interacting with a third-party autorouter, which does a good job although for anything more than a tiny board, it's slow. It is obvious that the router assigns a penalty for each via (feedthrough) equivalent to some length of trace, and it will keep trying to reduce vias and trace length until it can't find any more options. You might be very fussy and demand a better result, but it's always been good enough for me.
     
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  8. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    Personally I use Eagle, though you have to place the components yourself. I am assuming you're a newbie at PCB design, so I wouldn't expect you to understand the disadvantages of using an autorouter. I have tried a dozen different PCB design programs -- From Eagle, to DIPtrace, to FreePCB, to ExpressPCB, to Altium Designer, to Proteus, to KiCAD, etc -- and not once did I find an autorouter I liked. Nothing beats the human mind when it comes to laying traces. I can't recommend to you enough that you try to do it by hand. It may be a daunting task, and it may take you a while to complete, but the experience you gain from it is well worth it, trust me! All I can say is try to NEVER, EVER, EVER use an autorouter! They're complete rubbish!

    And of course I have to add in the obligatory video from Dave Jones on the EEVblog:

    http://www.youtube.com/watch?v=6JYG49zgEio
     
  9. John P

    AAC Fanatic!

    Oct 14, 2008
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    I think you're exaggerating, and so is Dave Jones. It's a judgment call to say that putting more work into something is necessary, and also a judgment call when we say "It's good enough". At least in a professional environment, our own labor is a resource that we shouldn't waste--so when do we say that we've got an adequate result? There's never going to be a clear answer to this.
     
  10. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    I am not exaggerating at all. I cannot stress enough the importance of learning to do things yourself instead of trying to get a stupid machine to do it for you. It doesn't know what is the best layout the way a human being does. Algorithms may work with parts of a design, but for others it will completely destroy it, over-complicate it, etc. It's just not worth it. At least for newbies, I strongly encourage you to try it on your own, do the layout yourself, and learn how laying traces works. When you're more experienced with PCB design you may choose to use an autorouter, though real experienced designers understand how useless they are and don't use them at all, or at least know how to fix the awful layouts they produce.
     
  11. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    If you're lucky.

    part of my last job was fixing the damage done when auto routers screwed up analog circuits.

    I think our guys used Protel but you still needed an operator with a brain to avoid problems.
     
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  12. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    Well, I was going to say right after I build up and test the prototype board to verify performance......:eek:

    That makes me sound so OLD......

    Used to be a pretty clear answer.....
     
  13. tindel

    Active Member

    Sep 16, 2012
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    I agree with Derstrom on some level. Every part (and I mean EVERY part) should be placed by hand. Then use the auto router to place matched impedance lines and differential pairs at the start of the design (something that is pretty rare for hobbyist, I suspect), then all of the 'important' stuff should be placed by hand, and finally the stuff you don't care where it goes can be placed by the auto router.

    Auto routers don't understand signal flow. They don't understand that the op-amp is sensitive to noise and needs a ground ring. They don't understand that the FET needs to source 30A so it needs to be connected to a large power plane. All the auto routers know is how to connect the dots.

    Hell, I have a hard time communicating with my layout guy to get the layout right... I doubt I can tell the computer how to layout my card. Of course, the computer wouldn't take liberties with my design either though. Why my company even insists that I don't do my own layout is beyond me, but I digress, as that's a bit off topic.
     
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  14. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    My opinion is that autorouter is not a completely useless thing, but you first need to be good enough at routing boards to know what you can leave for the autorouter and what needs to be done by hand.

    The only time I use autorouter is with two layer boards to see how well the components are placed and if it even is possible to layout the board. Then I delete everything and route it by hand.
     
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  15. nigelwright7557

    Senior Member

    May 10, 2008
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    PCBCAD50
    It can auto-place, swap autoplace and place and route repetitively to find best layout. You can also stop it moving certain components like edge connectors.
     
  16. John P

    AAC Fanatic!

    Oct 14, 2008
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    As with any automatic device, you have to know what an autorouter will do, and you have to know how to evaluate its output. Dealing with noise-sensitive items and high currents are good examples. But then, a lot of circuits are not very demanding in terms of layout, and you can get away with something that just "connects the dots", like a board that uses a PIC or AVR processor and some simple digital or analog peripherals--the kind of thing people on this board typically build. Come to think of it, the autorouter is like any other tool, helpful if you know how to use it, and capable of doing damage otherwise. So if anyone says "NEVER, EVER, EVER use an autorouter!" I'm going to respond that he's exaggerating.
     
  17. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    You just summed up why I don't use computer aided design tools or sims: you let them "work" and then you have to verify what they did. It's like having a really stupid tech so that you give him something to do and when he's done, you have to 100% check what he's done which takes me more time than it would have taken me to do it myself. And by definition, you always have to be smarter than the computer to know when it's lying or telling you something stupid.
     
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