Gregory Chen's Rancilio Silvia Espresso Machine Enjoys a Bit of Raspberry Pi in This IoT PID Upgrade
Built in the Go programming language on a Raspberry Pi 4, the Espresso Controller offers fine-grained control and monitoring.
Developer Gregory Chen has shared a project designed to bring a little bit of the Internet of Things (IoT) to your next cup of coffee: a Raspberry Pi-based temperature controller for the Rancilio Silvia or compatible espresso machine.
"[This is a] PID temperature control and monitoring for a Rancilio Silvia or comparable espresso machine," Chen writes of the project. "The application is a single Go binary implementing: gRPC API as defined in espresso.proto; dashboard web app using React and Material-UI; and /metrics web endpoint for Prometheus scraping; serving on a single port (default 8080) of a Raspberry Pi."
On the hardware side, the built uses a Raspberry Pi 4 Model B single-board computer (SBC) connected to a K-type thermocouple, a MAX31855 thermocouple amplifier, and a solid-state relay to take care of actually controlling the heating element within the espresso machine — a Rancilio Silvia, in Chen's case, though the core technology should be applicable to almost any espresso machine.
When active, the controller serves up a web page with an interface which graphs the current temperature measured by the probe, reads out the precise actual temperature and compares it to a user-configurable target temperature, and offers a few system statistics from the Raspberry Pi as an added bonus.
Chen warns, however, that the lower-cost Raspberry Pi Zero family, commonly used in embedded projects owing to its extremely low cost and small form factor, isn't suitable. "The Pi Zero W, having a single processor, will experience performance issues," he writes, "because it will not handle the necessary concurrency well (needs to measure temperature, toggle heating elements, and serve the UI static files/requests)."
Chen's controller has been published to GitHub under the permissive MIT license, along with a wiring diagram for fitting the completed add-on to the Rancilio Silvia.