The Apple II Daisy Chainer for Floppy Emu is done, and I’ve ordered a few PCBs made for testing. This proved to be a surprisingly challenging board to lay out and route the traces. It’s a simple two-layer board, and I wanted to keep it as small as possible, so the signal routing quickly became very congested.
Hand-routing of the first 40 traces took almost a whole day of tedious work, so I finally gave up and tried autorouting the remaining 80 traces. And it worked! The result looked pretty good, too. I’m curious to know how autorouting has turned out for other hobbyists. Have you ever autorouted nearly an entire board? What were the results?
We’ve all tried autorouting with Eagle and found it lacking – here is what BMOW did:
I haven’t had good results with Eagle’s built-in autorouter, so for recent projects I’ve been using a stand-alone autorouting software package called Freerouting. It’s a Java-based app with a slightly awkward UI, but it’s impressively powerful. First you export your Eagle board file in .DSN format, using a script provided by Freerouting. Then you import the DSN file into Freerouting and let it work, running for about 1 to 15 minutes. When it’s finished you can export an Eagle session script, which will rip up all your old tracks and lay down the new ones calculated by Freerouting.
Obtaining good autorouting results requires careful setup of Eagle’s design rules. For example, the default might be to use 8 mil traces with 8 mil minimum spacing between traces, but power and ground might be treated as a separate net class requiring 20 mil traces for extra current-carrying capacity. The design rules also define what size drill to use for vias, and how close to the edge of the board it’s OK to route traces. The autorouter takes all of these constraints into account when it does its job.
Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, or even use Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for MakeCode, CircuitPython, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.