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Altium vs Orcad

Discussion in 'Electronic Design' started by Jon Slaughter, Oct 16, 2007.

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  1. ? When I turn off routing for the bottom layer I cannot get a working
    autorouted layer.

    The problem is that I don't know where to put the jumpers to maximize the
    routing for autoroute. I'm sure there are places where I can put it and it
    will be quite useless and still have uncompleted connections(now it probably
    increases the likelyhood because it gives an alternate route but I'm nots
    ure... I guess thats something I'm going to have to try and see though)


    Thanks,
    Jon
     
  2. I meant what kind of future designs are you looking at doing. $10K
    package like Altium is overkill for simple 2 layer stuff.
    When you generate Gerber files for manufacturing, you will get top and
    bottom layers as seperate gerber files, or you can tell the software
    to only generate the bottom gerber layer. Just send the bottom layer
    file to the manufacturer and bingo, you have a single sided PCB.
    You shouldn't be using an autorouter at all!
    Especially for that incredibly simple circuit.

    Dave.
     
  3. Do they automatically route them or something? or convert the vias into
    jumpers? I don't understand what th gerber file contains? If its info for a
    routed board and if I routed it with vias then I can't see how they can fix
    that?
    huh? Why can't I? And the circuit is not so simple? Remember, its 8x each
    mosfet and not just one. Its got almost 100 nets involved. Doesn't seem all
    that simple to me(It might be simple in the grand view of things but if its
    so simple then autoroute shouldn't ahve any problem at all with it).
     

  4. When all you are doing is a single layer board, how hard can it be to
    hand route it?

    It would seem that auto routing it would even be a poor choice.
     
  5. Paul Burke

    Paul Burke Guest

    So does little brother Easy-PC.
     
  6. Jon Slaughter wrote:

    [ stuff about autorouting, autoplacing, auto-pinswapping ]

    Hi Jon,

    I don't know your motives for using an autorouter, but the general consensus
    among pros and amateurs (but especially pros) is that autorouting isn't
    worth the trouble.

    I, personally, find the results aesthetically abominable, but then the only
    autorouter I have experience with is Eagle's, and that one is really crappy.
    I've heard good things about the Bartels router.

    In general, autorouting is OK for simple boards with mainly non-critical
    signals, but those you might route by hand just as quickly. Complicated and
    critical boards need to be routed by someone who understands the circuit, so
    an autorouter is out. Upshot: Why bother with autorouting at all?

    robert
     
  7. Haude Daniel

    Haude Daniel Guest

    Something as primitive as that can be hand-placed and hand-routed
    in 15 minutes and it'll even look good. With repetitive elements it's
    important to figure out once how to lay out the power buses, from then
    on it's just fun.

    Here's a 5x5 relay cross switch I'm working on. Routing
    took a single afternoon because essentially it's N times
    the same thing. (I've done boards less than half that
    size that took me a week.) An autorouter would have made
    a complete mess of it because it would have tackled the routes
    one-by-one, completely oblivious to the big picture. It
    also wouldn't have done the guard traces for the
    MCX connector's shields, and it wouldn't have done such a nice
    job of routing the DB25 connector.

    http://s2.supload.com/free/pcb.png/view/

    Knowing me I'll spend another day tweaking the layout and especially
    the silk screen layer.
    What you should do is hand-route it as a two-layer board,
    taking care to make the traces on the bottom layer (=jumpers) straight.
    To manufacture the PCB, you just use the copper data (=gerber file)
    of the top layer and do the jumpers by hand.

    Depending on your design rules you may or may not be able to route
    between 0603 pads, which will greatly influence the number of jumpers
    needed.

    --Daniel
     
  8. Well, the boards I'm working are simple and I figure it would be much easier
    just have it do it. Instead of a few hours routing it(potentially) it takes
    a few seconds. Of course thats if I was working with two layers. Because
    its one layer its impossible to route without jumpers(and I'd have the same
    issue manually routing but at least I could manually add jumpers quite
    easily)

    I guess I'm going to have to do it by hand or modify an autoroute since I
    can't seem to figure out how to efficiently use jumpers(having to use 0-ohm
    resistors seems like a hack and is probably just as much trouble)
     
  9. Your are using more than one layer. Try do that with a single layer and no
    vias... then is it easy?
    I'll probably need to change it, right now I can but I'd rather have larger
    trace widths. Its a mess the way it is and I doubt anyone could route it
    manually on a single sided board without using jumpers(cause many of the
    components can be easily trapped and not be able to connect to to any other
    components(That is the problem with autoroute and no jumpers), at least in
    15 mins. That said, I doubt one would need any more than 8 jumpers.

    I'll try and route it manually and see what happens. I guess I just expected
    more of auto routing.

    Jon
     
  10. A gerber file is the output file you send to the manufacturer (you can
    also just send the Altium/Orcad file etc). Google will tell you all
    about gerbers I'm sure.

    *ANY* PCB program can be used for single layer design by using the top
    layer for the links. Then all you do is manufacture the *bottom layer*
    only, simple.
    Nothing needs to be "fixed" or "converted", your vias (or pads) become
    the holes for the links.
    You can, but you shouldn't!
    You have fallen into the classic beginners trap. Autorouters are not a
    tool for beginners or simple circuits, they generally produce
    *horrible* results, and the simpler the board, the more horrible a
    result you tend to get. Especially for "single sided" boards!

    Autorouters are designed to be used by very experienced PCB designers
    who know how to set up the rules correctly and can use it in a
    controlled manner. A beginner using an autorouter is asking for a
    disaster.

    Do yourself a *big* favour, take some pride in your PCB layout and
    learn to route everything manually. Autorouters are a very *bad* idea
    except in specific cases, especially for you and your particular
    circuit.
    Wow, 100 nets!
    Any half decent PCB designer can manually route 100 nets in probably
    10 minutes. A beginner might take maybe 30 minutes?, an hour?, two
    hours?
    100 nets is nothing.

    What's more, with a "multi-channel" design like you have it's even
    easier. You just route one channel and then copy and paste the other
    channels. Then you connect the I/O and power, it's really simple.
    No it won't, but it will produce a horrible result.
    Try it and post your result here for comment, and you'll see what I
    mean.

    As for your original question of Altium vs Orcad. These are high end
    packages that cost a lot of money and appear to be gross overkill for
    what you need. Unless you want to do big complex boards and designs,
    any cheap basic PCB package will do what you want.
    Is this for work or home? What type and complexity of boards will you
    be working on the future?

    Dave.
     
  11. I know what a gerber(well, basically) is but I don't see how leaving off the
    bottom layer helps in preventing vias without causing the whole pcb to be
    worthless. I have no experience with sending in a board to be manufactured
    though and have only etched my own single sided boards.
    You mean that I have to connect the "links" myself or they jump them at
    manufactoring? Obviously if there are throughholes with the vias you can
    link them using whatever method you want but htey have to be linked because
    that is the routing for the circuit. Running a wire or jumper instead of a
    copper trace is the exact same thing as far as its still bottom layer work
    and requires holes. I'm tired of drilling holes on single layer and that is
    why I'm trying to smt work but I thought I could get away with no holes with
    it and just a few jumpers.

    The results are fine if its got more than one layer. The result is
    impossible for single sided. The problem is, is that the auto router isn't
    intelligent enough to insert jumpers to make it simple enough.
    I figure the autorouter is smarter than me but maybe not? Most of the pcb's
    I've done are very small and actually could be done with just a few jumpers
    but were all TH. (so jumping was pretty easy)
    Ok, can you route it in 10 mins on single sided(no vias)? I don't see how
    you can do it very well without adding a lot of jumpers. Sure I can route it
    in probably 20 mins(as I just did) but I still cannot route some nets
    because they require jumping and jumpers won't fit near the components
    because they are tightly compacted. Sure its an easy think of every
    component has 1in^2 to itself.

    I'm not saying its necessarily hard but you guys seem to make it sound like
    its a walk in the park. I agree with vias it is and if you convert those
    vias to jumpers then its the same thing as using a bottom layer(essentially
    because it requires holes.. in that case I might was well just get a 2 sided
    board and etc both sides and drill the holes).
    lol. I don't think so. I think you need to actually try the circuit I did.
    Show me if its so easy ;) (remember, single sided) When I route it every
    component gets in the way of some other component. If you route around it
    then it blocks 3 more. I don't think its as easy as you think.

    Basically on single sided, when you supply power to each channel it cuts off
    routes for every output of the device(or input) so you have to jump for each
    one. Then supplying the ground it cuts off the input(or output) and you have
    to have around 16 jumpers. Maybe it can be optimized for less but I don't
    think it can be done well in 10 mins unless you through jumpers all over the
    place. I'm trying to minimize jumpers because its smt and I'll probably have
    trouble soldering the components specially when traces go through pins. I
    also want it to look decent without 100 jumpers all over the place.

    So if you mean that "It can be routed in 10 mins" then I'm sure it can...
    but how well can it be done? Can you do it in 10 mins without any jumpers
    and minimize space? I'd like to see it. Can you do it with just 3 jumpers
    and no TH's/vias?


    The result isn't horrible but incomplete(well, its messy). With 2 layers its
    not so bad.
    Its for home but I eventually would like to make more complicated stuff.
    I've used the PCBExpress software and routed my own powersupply a while
    back. It wasn't difficult but there was no need for so many jumpers as in
    this case.
     
  12. Extremely simple: Just route them as straight tracks on the other side of
    the board. When you get the finished (one-sided) board, it'll have the pads,
    copper, drill and all, into which you can solder your jumper. No need to
    include jumpers or 0-ohm-Rs in the schematic.

    Is it possible you've never done PCB layout before?

    robert
     
  13. What? There is no other side. ITS SINGLE LAYER!! sheesh. How many times do I
    have to say this. So what happens? When you do it for two layers to get the
    "virtual jumpers", guess what? The end up going from one side of the board
    to the other. So do you expect me to run wires like a spider web all over
    the board?
    Yes I have but its always been single layer, manual routing, and smaller
    components. I did a power supply that had 4 linear regulators, two variable
    and two fixed on a 2inx2in board. It was easy because all "channels" had
    only 3 "ports". I had like 3 jumpers. In this project every channel has 5
    ports and about 15 components gets boxed in. Sure I can use vias but then I
    have to jump from one side of the board to the other cause the autorouter
    doesn't minimize the length of the traces on the bottom side(mayber there is
    a rule for that though).

    Now I can easily route the board and put in jumpers manually but its not
    efficient and not the best way. I want to learn to the best way(or a better
    way) for future projects too. Your method isn't very good because the board
    its end up a lot of jumpers that are not needed and to long.
     
  14. I have to admit that the routing has to use jumpers because of the design.
    That is not the problem. The problem is to minimize the jumpers. Its quite
    easy just to use jumpers haphazardly and get a route. I can do that in
    about 10 mins. (even minimize the jumper length in the process) But that
    doesn't mean its the best way to do it. (of course maybe I should just do it
    anyways which I actually am because that seems to be the only way. I end up
    using 0-ohm resistors because it looks nicer than a much of jumper wires
    cluttering up the board)
     
  15. It won't be worthless. The vias are what you solder your jumpers into.
    That's going to be difficult if you can't do 8/8 rules because you'll want
    to route between SOIC and 0603 pins.
    You could jack up the "cost" for vias and for routing and bends on the
    opposite side, then you'll end up with few, short, straight jumpers.
    What is indeed a walk in the park is the decision of whether you can do
    truly via-(jumper-)less design based on whatever your design rules are. When
    your design rules allow 2 traces underneath 0603 parts or between SOIC pins
    it might be doable. If you can't do either, it's impossible.
    Yes, you might as well. One-sided layout is a lot harder (if not impossible)
    using SMD. Your SMD board might end up having lots less holes than the
    corresponding through-hole design, but it'll still have plenty.
    Welcome to the reality of PCB routing. The problem is not a lack of
    intelligence of you or the autorouter, the problem is that what you're
    trying to do is simply impossible single-sided.
    That's just topology, and no amount of computing power will get around that.
    To get to an island you'll have to use a boat (or an airplane, or swim, or
    dig a tunnel) and that's that. 16 jumpers would have been my estimate as
    well.
    It won't take as much as 10 minutes to figure out that you can't reduce the
    number of jumpers.
    Unless you can get plenty of traces between 0603 and SOT-23 pads you'll have
    to live with the jumpers.
    No. Who could?
    Better get into double-sided PCBs.

    robert
     
  16. Haude Daniel

    Haude Daniel Guest

    No, then it'd be simply impossible. I just posted the layout to
    demonatrate that a seemingly complex PCB is routed quite easily
    if there are plenty of repetitive elements.

    --Daniel
     
  17. I put a rule that said minimize vias and I guess it did but it still made
    the length minimal so a simple small jumper would work(even when it could).
    No, its not doable in those cases either, in general, It becomes a maze
    essentially and its easy to get into a dead end(so maybe there is even a
    mathematical solution but chances are the autorouter will find it will be
    0).

    My point is not to find any jumperless solutions cause there isn't any in
    this case. But to minimize them as I have said repeatedly. I think that is
    the difference between what you guys think is easy and what in reality is a
    hard problem.
    I suppose you mean jumperless routing? Yes, I know. Minimize jumpers? Not
    impossible at all. Difficult? Maybe.
    Well, I don't have any real experience with it and for the smaller pcb's I
    just used jumper where I had to but I did minimize them to some degree. I
    didn't just put a jumper when I needed it but I thought about the best place
    to put it.
    I don't agree. It depends on the placing and orientation of the components.
    Changing them can have a drastic effect. Now maybe there is some type of
    theorem which states the minimial number of jumpers need but I doubt it.

    I guess the problem is that I shouldn't be worrying about perfection to much
    here and just get it done. Although the difference between 16 and 8 jumpers
    a big difference to me.
    hehe, yes yes yes... I know... but how many? Maybe tons of jumpers are
    normal on single sided layouts of any complexity?
    Don't know. Thats what I got from you and David. Acting like its easy to do
    it. (normally when you do something you don't try and do it half ass so I
    take it when David said do it in 10 mins it means he could do it very
    efficiently(very few jumpers, maximal density, etc...)).

    It seems like a lot easier. But for such a small project here I don't see
    any need. I don't have any double sided boards at the moment so one I use up
    my single sided I'll probably start doing that or I'll start sending them
    off for manufacturing.

    But this project is pretty small and its a good learning experience and I
    need to do some more etching myself since I haven't done any in a while.

    I guess I might just be epecting to much. I thought you guys were implying
    that it was very easy to do an optimal route in a few mins and I was having
    trouble believing that. I guess though its my nature to want to make
    something the best I can but I'm going to go ahead and just try to route it
    and worry about optimization some other time when it actually matters.

    Jon
     
  18. yes, but you used two layers. I never said that using two or more layers was
    difficult. What I am finding difficult is to use single layer, maximize
    density, and minimize jumper and jumper length(well, actually I guess a
    fixed length would be ok). I was under the impression that you guys were
    saying this is easy. Of course now I get the impression that it is not and
    so I don't need to worry about it to much(this project isn't all that
    critical so no big deal). Of course this started from the autorouting
    approach and I thought that maybe it could find the optimal solution.... but
    seems auto routing is not as good as I thought it would be.


    I'm just going to go ahead and route it and put jumpers in where they need
    to go and not worry about optimizing it. Shouldn't take to long to do that.
     

  19. There is a useful compromise that I use when I do a "home-made" SMT
    board.

    Route the board "single sided" but with a ground plane on the opposite
    side (with vias for ground points). Then make the board with double
    sided material, but only etch the "tracks" side. Drill the ground
    connections and use through-pins soldered both sides (or bits of
    resistor legs etc) to connect the ground vias to the ground plane.

    - no alignment issues, drilling not critical

    - very good quality signals and power bypassing due to ground plane

    - the "ground" signal usually has the most nodes, so removing it
    from the tracking layer frees up lots of routes, often enough to
    be able to complete the rest of the design single sided.

    - You *can* use through hole parts too, but you then need to isolate
    the "non-ground" pins. This can be done by countersinking on the
    groundplane side with a suitable drill bit, and you need to solder
    on the tracking side.
     
  20. You shouldn't be using an autorouter for single-sided, period.
     
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