When to Use an Autorouter in PCB Design

[@envisionelectronics]

I’m relieved that the official video on autorouting from Altium looks just as shitty as the results I got the one time I tried it.

[@DannyBokma]

I often get payed by the hour. Ill do it myself manually ^^.

[@Zachariah-Peterson]

Best comment ever

[@ehsanbahrani8936]

Thanks a lot Mr. Peterson. Can i use Auto routing or Active routing to rout FPGA DDR3 ?

[@Zachariah-Peterson]

Don't even try autorouting with DDR3. You could do it with ActiveRoute but you will have to go back and apply delay/length tuning across the entire bus.

[@JeffreyBoye]

Forget auto routing, I'd like to see Altium implement an auto tuner. That will save time!

[@Zachariah-Peterson]

There is an upcoming video about this, you'll see it come around soon!

[@videoaccount5676]

Short answer: Never

[@Zachariah-Peterson]

You've earned a like sir

[@playitlouder451]

Sometimes on big boards with lots of stuff going everywhere an autorouter is the way. The autorouter is seen (not Altium) requires a script to set set it up. Something like 1. Select clock nets 2. Route the selected nets using a star topology on outer layers with impedance 50 Ω. If they're diff pairs you have to tell it that too. 3 Select the high speed data busses. 4 Route them equal length, and as diff pairs if needed, with tolerances. I.e. you have to do a really good job setting up the rules and priorities, which is 90 % of the work. Then let it run. Come back the next day and see what worked and what didn't. Modify the script a bit and try again. After a couple of goes it works and you have a script you can run any time. The advantage is that if the placement needs to move around a bit you don't have to redo all those hand-crafted matched lenght diff pairs over night. Just start the autorouter and come back the next day.

[@Zachariah-Peterson]

This is the kind of thing I was thinking of with a process to use it, I just don't know what the best process is or if it can really be generalized to every other possible board. Sounds like in this case maybe it can't be generalized to every other board. And I agree a lot of the up-front work would be to set rules, constraints, and priorities.

[@thomaserikssen4792]

Interesting; seems like a case of "you need to know how to use your tools". Which autorouter are you talking about, and where can I get it?

[@CleberMag]

Altium Designer has proven to be an excellent tool ever since I first started using it, and today, its capabilities are truly impressive. However, I understand why the autorouter still falls short: it lacks the ability to comprehend our intentions and the contextual nuances of the board. I mean, I've tried implementing numerous rules to guide the routing process, and while it does a decent job, the time invested in fine-tuning these rules and addressing issues, like those encountered here, indicates that manual routing remains the preferable option. That said, leveraging the automation features within the software, such as configuring push tracks and optimizing common I/O pins through multirouting, significantly expedites the process beyond the default settings and proves to be far superior (and faster) compared to autorouting.

[@afre3398]

How do I turn off auto routing on a specific layer?? I have problem where I want to do copper pour on a bottom layer (4 layer card). Because altium want let me select bottom/top layer as a power plane

[@Zachariah-Peterson]

If you're going to use the autorouter, you can limit it to specific layers, or specific layer transitions through vias, when you open the configuration dialog. If you want to do copper pour on the bottom layer, then wait until you have the PCB fully routed, then you can apply copper pour on the bottom layer as a polygon. Make sure to set the right copper-to-track clearances for the GND net in the Electrical -> Clearance section of the design rules.

[@petertwiss356]

I tried it once back in 2007. I wonder how good it is if you set the classes/rule super well.

[@Zachariah-Peterson]

I have no time to experiment with that

[@petertwiss356]

@@Zachariah-Peterson yeah me either lol. maybe one day I'll save a board after placement, do the route myself, and then go back to the placed board and see what it comes up with.

[@FR4-Pilot]

Situs? You can set all the classes/rules you want and it will disappoint. Try a real autorouter like Specctra/CCT or Electra, learn the setup & control language, create and tweak your do files, place route-keepouts in your design, learn when/when not to use one, and see a whole new world of what autorouters (and you) can do in a fraction of the time. Altium could never create or acquire a professional autorouter thus they began the propaganda that all autorouters suck. If you think you can simply load your board, push the autoroute button and then complain about the results you're an amateur.

[@karlbesser1696]

It is often better if you place the components yourself according to the circuit diagram and then let the auto router make a suggestion about the wiring.

[@ThePaulus2010]

There are only 2 kind of people who like autorouters.. The ones who do not know what they are doing and those who sell them..

[@Zachariah-Peterson]

LOL that might be true

[@mamadoudiatta9877]

What if you have more than 1500 nets???

[@ThePaulus2010]

@@mamadoudiatta9877 1500 nets is not that much. If you have 3000 components you have a lot more than 1500 nets.. .yes it will take effort.. But it's never gonna be good if you do it with an autorouter.

[@tigegibson7528]

I think you forgot the link.

[@Zachariah-Peterson]

Which link? There are two links in the description

[@winsrrow8125]

when to use autorruter -> never, just use interactive routing jajajajajjaja.

[@FR4-Pilot]

I thought Altium was anti-Autorouter ? Active-route, or smart-route, or gloss, or whatever ... Please don't tell us Situs is a legitimate autorouter.

[@Zachariah-Peterson]

I'm not advocating for or against, but I'm more curious if anyone actually uses it. We've talked to customers that say they do use it, and so it piqued my interest.

[@87Spectr]

my boss ask for me use autoroute but I will never give up!=)

[@nulldev42]

Why oh why does the autorouter create shorts on existing nets??!? I can understand dealing with some non-optimal corners or routes after the fact, but creating a direct short? Thanks just awful coding.

[@Zachariah-Peterson]

I actually wonder if you were to rip up that net, and then iterate and target that net specifically with the autorouter, that it might give a better result. If the other nets are already routed then the tool can only focus on obstacle avoidance rather than balancing two routes simultaneously. I haven't done the experiment though.

[@hisham1269]

it's hard to believe that auto-routers are this bad, this video does not make sense, someone needs to explain it better 'officially'.

[@Zachariah-Peterson]

Unfortunately there are no "official" explanations or workflows. I sometimes see people do it on groups of nets on the same layer, which seems to work okay when routes are short and all the components are grouped together. I have noticed that as soon as a layer change is needed, the resutls get very weird.