Some people take their coffee grinding seriously. So what do you do when the hot new grinders automatically weigh coffee, and yours doesn’t? Well, if you are like [Tech Dregs] and the rest of us, you hack your existing grinder, of course. The link is to the source code, but for a quick overview, check out the video below.
In true hacker fashion, the first order of business was to pull a load cell out of a cheap scale. Originally, he intended to reuse the processor inside, too, but it was epoxied, so it was a good excuse to use some more modules. A load cell amplifier, an OLED display, and a tiny Xiao processor, which he describes as “ridiculous.” From the context, we think he means ridiculously small in the physical sense and ridiculously powerful for such a tiny board.
With the modules, the wiring wasn’t too hard, but you still need some kind of app. Thanks to App Inventor, an Android app was a matter of gluing some blocks together in a GUI. Of course, the devil is in the details, and it took a lot of “focused cursing” to get everything working correctly.
The coffee grinder has a relay to turn the motor on and off, so that’s the point the scale needs to turn the motor on and off. Conveniently, the grinder’s PCB had an unpopulated pin header for just this purpose.
This is one of those simple projects you can use daily if you drink coffee. We are always impressed that the infrastructure exists today and that you can throw something like this together in very little time without much trouble.
WiFi hacking coffee makers is a popular Java project in these parts. Upgrading a machine can get pretty serious with PID control loops and more.
“Some people take their coffee grinding seriously”
Then there are the monsters and degenerates.
You are, of course, absolutely right.
A true coffee aficionado (nutcase) would measure out the beans from a sealable container, then feed them to a no-retention grinder.
This gives me an idea. Drug dealer’s scale under the Melita filter cone, tare. Flip the switch on my Kitchen Aid mid century grinder. Seconds later just the right amount is in the filter. Then perch on the cup set under the dripper push go. Mmm.
Drug dealer’s scale?
Triple-beam dream!
Espresso cream–
or is it crema?
No dilemma
. well done. I love your tenacity. You didn’t know how to do the Arduino and Android BLE thing, but just worked on it period until it got done.
Great work! Seeing the slowness of the weight updates on even an 80€ coffee scale got me thinking about the very same project. I’m not quite sure why a scale with more speedy updates has to cost almost 200€ (Acaia).
I actually have the Libra grinder but I’d do this to measure the espresso yield and stop dispensing the water automatically once a certain yield is achieved.
I’d use that oled screen with some physical buttons rather than a phone to control it. Phone could be useful to draw a graph of yield vs time but not sure if any conclusions can be made from that (like good vs bad shot).