Grind Finer with a Rasperry Pi Pico

We’ve done loads of stuff with Raspberry Pi computers lately. Fixing a microcomputer to a teasmade from a half-century ago and making it speak internet, was a nice bit of upcycling. In this case, the problem was a little more simple.

Different coffee brew methods require coffee that is ground to a different coarseness. Getting it just right is known as ‘dialling in’ and a dialled-in grind is a beautiful thing. Adjusting some grinders from fine espresso grinds to coarse pourover grinds seems to take forever. Invariably, you forget where it was when you started and you’ve most likely ruined the next cup of espresso you’ll be having.

The brief was pretty simple: Make the adjustment of the grind size manual and give it a memory so that you can reliably switch between brew methods without wasting coffee by having to dial in again.

We used a microcontroller (a Raspberry Pi Pico), connected to an OLED, a rotary encoder and a DC Motor, attached to a Bezzera BB005 coffee grinder. The code is on github and at the time of writing is very simple; just an electric adjustment and a display of the last few grinds. If you feel like making improvements/ suggestions, do it via the github repository.

There is plenty of scope for refinement. If a calibration step is built in to avoid ‘drift’ between grinds, then the code can store all grinds it performs. If it can collect other parameters (via the user interface) then it can start doing smarter things. Anyway, here’s a video of it in action: