3 ms·

> I worked with an RF engineer who'd been in the field since the 70s, and he'd always use the auto-router for anything "slow". If it was "digital dc" or digital

> I worked with an RF engineer who'd been in the field since the 70s, and he'd always use the auto-router for anything "slow". If it was "digital dc" or digital logic or under a MHz then it was auto-routed because he didn't have time for that. Anything critical that carried RF or drove a reference was hand-routed first then anything left would get the auto-routing treatment. And this was in a radio astronomy observatory! Your example perfectly illustrates that autorouting is a catch 22: in order to get something useful out of autorouters you either have to (a) provide them with a enough information on signal, DRC, and fab parameters OR (b) have a design so simple that it doesn't really matter. (a) requires subject matter expertise that beginners won't have and (b) really is such simple point and click that beginners don't gain anything from an autorouter. The beginner already has to learn enough to place components on the board before routing, which IMO is where 80% of the leverage of expertise comes in anyway. The calculation changes if you're all bought in on an EDA package like Altium and you know all about modular schematics and PCB docs on with standardized PCB layering. Then maybe you can start cobbling together quick designs that are largely autorouted but again, catch 22: you have to know enough Altium to know how to do that and enough electronics to know how to select open source modules and parts.

neltnerb 3y ago
I spent long enough getting tired of routing low impact traces that I actually learned to use the autorouter. And I mean *learned* because it was not as simple as clicking a button. Using it right means dropping down keepouts over sensitive areas so that the autorouter knows to stay away -- you know it, but it has no way to. It means placing vias to a ground plane next to every ground pin so that it doesn't try to deal with top layer ground planes breaking. It means telling it how much to penalize a trace for being routed on the power plane layer or the ground plane layer. [and on] It's a super useful tool -- if you are careful with it like you should be with, well, chatgpt. Give it all the information you know it needs to know, patiently and quantitatively, and sure it'll find a reasonably optimal solution. You just have to tune it as well as you tuned yourself. [edit: and you can do it in the reverse order for nasty piles of spaghetti nets that you can't smooth out with part placement, to get hints on where you'll have to run busses later so that you leave room -- but always route the sensitive traces first]

neltnerb 3y ago

I spent long enough getting tired of routing low impact traces that I actually learned to use the autorouter. And I mean *learned* because it was not as simple as clicking a button. Using it right means dropping down keepouts over sensitive areas so that the autorouter knows to stay away -- you know it, but it has no way to. It means placing vias to a ground plane next to every ground pin so that it doesn't try to deal with top layer ground planes breaking. It means telling it how much to penalize a trace for being routed on the power plane layer or the ground plane layer. [and on] It's a super useful tool -- if you are careful with it like you should be with, well, chatgpt. Give it all the information you know it needs to know, patiently and quantitatively, and sure it'll find a reasonably optimal solution. You just have to tune it as well as you tuned yourself. [edit: and you can do it in the reverse order for nasty piles of spaghetti nets that you can't smooth out with part placement, to get hints on where you'll have to run busses later so that you leave room -- but always route the sensitive traces first]