[Nathan] had an small router kicking around and thought that he might as well put it to good use. He had always been interested in getting a better handle on his espresso machine, and figured that the router would be a perfect Linux-based PID controller.

He installed OpenWRT on the router, then disassembled it in order to get access to the router’s GPIO pins. He built a small PCB that allows him to get temperature info from the machine to the router using i2c. [Nathan] put together a PID package for OpenWRT, allowing him to control the machine over SSH, though he may build in a user-friendly web interface sometime in the future.

He says that most espresso machine PID controllers he has seen come in the form of big ugly boxes slapped on the side of the machine’s case, though we have to disagree with him on that point. Opinions aside, he is going for a minimalist design, and while he says that he is only about half way through the project, we think things are looking promising so far.

When everything is said and done, we hope to get a much closer look at all of his code, schematics, and more information on the router he used as well.