3 ms·

> Placement is probably the big issue that needs to be solved now. Would some sort of constraint-solving algorithm help with that? Something like (but not nece

by ElFitz 4mo ago

> Placement is probably the big issue that needs to be solved now. Would some sort of constraint-solving algorithm help with that? Something like (but not necessarily) Cassowary[0]? Maybe I'm misunderstanding what is meant by placement though; I don't have much domain knowledge in PCBs / electronics. [0]: https://news.ycombinator.com/item?id=43362528 https://news.ycombinator.com/item?id=43362528

lambdaone 4mo ago
I've written my own autoplacer/autorouter. Placement is where you put the components on the board, routing is how you shape the traces to interconnect them. It does a pretty decent job on small hobby-project boards of ~40 components (which is my use case at the moment), and I'm working part-time in the background on scaling it further. The resulting designs pass all the KiCad electrical and geometry checks. Granted, I've spent about a year working on this problem, and it's hard, but not that hard a problem, providing you can avoid falling off the exponential cliff by decomposing it into hierarchical subproblems. Quick-and-dirty unsupervised whole-board synthesis from schematic takes about 5 minutes, longer if you want cleaner output with nicer-looking better-routed traces. As others here have said, placing is the real problem to solve, and that's where the magic happens. Place the components right, and routing is a relatively easy loosely-coupled constraint programming problem, place them wrongly, and you will have to get used to seeing the word UNFEASIBLE in your log output.
- throwaway2037 4mo ago
  This project sounds very cool. Is it open source? If yes, can you share a link to the repo?
- ElFitz 4mo ago
  That is fascinating. Thanks!
seveibar 4mo ago
We work on this a lot at tscircuit, and we've used cassowary (i.e. flexbox-style) constraint solvers. The issue with cassowary/flexbox is PCBs are not as uniform as webpages w.r.t. alignment, and often have a much less nested structure (3 layers) vs web pages which have many many nested layers. CSS grid-style constraints are a much better fit IMO, but we eventually settled on sequential optimal packing[1] for "seeding" a placement so that AI can get initial positions before working in a feedback loop. I like sequential optimal packing because it's very very deterministic and the constraints are specified pretty close to how a human would specify them [1] https://blog.autorouting.com/p/sequential-optimal-packing-for-pcb https://blog.autorouting.com/p/sequential-optimal-packing-fo...
- ElFitz 4mo ago
  The first thing that came to mind reading it was "backtracking". Which I guess is the recursive pathfinder piece?

by ElFitz 4mo ago

lambdaone 4mo ago

I've written my own autoplacer/autorouter. Placement is where you put the components on the board, routing is how you shape the traces to interconnect them. It does a pretty decent job on small hobby-project boards of ~40 components (which is my use case at the moment), and I'm working part-time in the background on scaling it further. The resulting designs pass all the KiCad electrical and geometry checks. Granted, I've spent about a year working on this problem, and it's hard, but not that hard a problem, providing you can avoid falling off the exponential cliff by decomposing it into hierarchical subproblems. Quick-and-dirty unsupervised whole-board synthesis from schematic takes about 5 minutes, longer if you want cleaner output with nicer-looking better-routed traces. As others here have said, placing is the real problem to solve, and that's where the magic happens. Place the components right, and routing is a relatively easy loosely-coupled constraint programming problem, place them wrongly, and you will have to get used to seeing the word UNFEASIBLE in your log output.

throwaway2037 4mo ago
This project sounds very cool. Is it open source? If yes, can you share a link to the repo?
ElFitz 4mo ago
That is fascinating. Thanks!

seveibar 4mo ago

We work on this a lot at tscircuit, and we've used cassowary (i.e. flexbox-style) constraint solvers. The issue with cassowary/flexbox is PCBs are not as uniform as webpages w.r.t. alignment, and often have a much less nested structure (3 layers) vs web pages which have many many nested layers. CSS grid-style constraints are a much better fit IMO, but we eventually settled on sequential optimal packing[1] for "seeding" a placement so that AI can get initial positions before working in a feedback loop. I like sequential optimal packing because it's very very deterministic and the constraints are specified pretty close to how a human would specify them [1] https://blog.autorouting.com/p/sequential-optimal-packing-for-pcb https://blog.autorouting.com/p/sequential-optimal-packing-fo...

ElFitz 4mo ago
The first thing that came to mind reading it was "backtracking". Which I guess is the recursive pathfinder piece?