Espresso Machine Control - HomeKit and Promtheus enabled
Usage of ./espressod:
-db string
Database path (default "./db")
-gpio
load gpio code (default true)
-maxTemp float
Maximum temperature value (default 130)
-metrics
Enable prometheus metrics (default true)
-minTemp float
Minimum temperature value (default 10)
-name string
Device name (default "Astoria Boiler Thermostat")
-pin string
Homekit Pairing PIN (default "00102003")
-promPort int
Port to reigster /metrics handler on (default 2112)
-stepTemp float
Temperature setting step size (default 0.1)
espressod is a standalone golang daemon that creates a Thermostat accessory for use in HomeKit. It also exposes most of the metrics relevant to the operation of the system via a prometheus instrumentation URI. Starting the daemon with no options will setup the accessory and try to control the boiler via a solid state relay. A momentary switch changes the setpoint from min to max and back.
I purchased a second hand commerical espresso machine a few years ago, and it is far too much work to turn it on and then wait the 30+ minutes for it to warm up fully. I was also concerend with how much power it was drawing. So I in-lined a 40A 250V Solid State Relay which I hooked to a raspberry pi, and wired a PT100 temperature sensor into the boiler. I now have very precise and very easy to automate temperature control of the machine.
Some details can be found on The Guru College.