Cameron Charles from The Adventures of Cameron Charles has a Saeco Aroma espresso machine and wanted a bit more control. Of course this means a custom PCB with an onboard microcontroller. Have a look his Espresso Machine Microcontroller Temperature Regulation project where he shows how he takes over control of exactly how the espresso is being made. There is still a small amount of tweaking to be made but the results look great (and I am sure they taste even better).

“I set about designing a board based on the Atmel ATMega328 microcontroller. I put on connectors for the various I/O devices (among other things, I would need to read the state of the “Steam” button to adjust the temperature setpoint), a solid state relay for controlling the heater (I would be using a PWM-based approach to adjust the gain of the system and having a mechanical relay switching a few times a second would get pretty noisy), and I also added some extra features for future expansion (such as a second solid state relay for taking control of the pump, it would be pretty cool to also use a PID algorithm to regulate the water pressure when pulling a shot!). I also added a 120VAC to 5VDC conversion circuit to the board as I wanted the Espresso PID board to be able to scavenge power directly from the Saeco Aroma so that it wouldn’t need to be plugged in separately or require batteries.”