Thank you so much for the feedback. This forum rocks!
I want to provide more details on what I am trying to do.
1) I want to keep the normal function of the buttons of the Gaggia Classic.
2) I want to have gravimetric brew control using the Lunar scale (https://acaia.co/products/acaia_lunar
). This is a popular scale with BLE. The idea is to turn on the scale, press a button on the raspberry pi and brew a predefined amount of coffee by engaging the brew function and then stop it and potentially control the pressure.
This is the current plan/progress:
The first challenge was to sort out how to communicate with the Lunar scale. They have an sdk for iOS but no support for other OSs. So I ended up writing a Python module myself: https://github.com/lucapinello/pyacaia
To simulate the press of the brew button in front (this is the relay I had in my previous picture) I am planning to use this shield: https://www.bc-robotics.com/shop/raspbe ... relay-hat/
. I tested and it works really well.
To modulate the pump I was planning to use this smart light dimmer with Bluetooth, I already got one: https://www.amazon.com/gp/product/B01I24JBNW/
(they have a python library)
Your dimmer module looks amazing and it is cheaper! Do you have a repo for the code that controls this? If I am not satisfied with my dimmer I will get this one!
At the press of the button on the raspberry pi this will happen:
1) Lower the dimmer to get about 1-2 bars
2) Engage the relay to simulate the brew button
3) Ramp slowly the dimmer to reach 9 bars
4) As soon as the scale reads 24 grams disengage the relay to stop the brewing
This is the schematic of what I am trying to do:
Thanks again for the nice feedback and suggestions!