Add a brew-by-weight to an espresso machine via a bluetooth scale. When the new brew button is hit, use a relay to "press" the single-shot brew button on the espresso machine, and hold until the weight threshold is reached. If we want, we can put in an offset to account for overshoot.
- initialize everything and wait for the scale
- rotary to pick a stop-weight and "go" (reflect current target weight on alphanumeric)
- tare scale
- turn relay on (wired to the 1-cup brew button on an Ascaso Steel Duo)
- when scale crosses threshold (maybe with epsilon?) turn relay off and await next click of the go button.
Hardware used (lazy mode from SparkFun):
- SparkFun RedBoard Artemis
- I'm pretty sure any qwiic + ble board would work. The nano version of this seems promising, but untested. Aretmis Nano
- Obviously you could do something similar without qwiic if you want to run your own i2c etc.
- SparkFun Qwiic Alphanumeric Display
- SparkFun Qwiic Twist - RGB Rotary Encoder Breakout
- SparkFun Qwiic Single Relay
Decent Scale (v1.2) Decent's scale API
Ascaso 'tech dossier' for Steel wiring diagram
NOTE: A lot of stuff in the machine runs at line-level voltages (heaters etc.) so unplug before you open it and be careful! Removing the top of the case is just 2 hex screws in the rear. It's attached by wires for grounding + the cup heater. There is enough length to set it aside.
I wanted this to be fully reversable. Although the crimps are.....bad (couldn't find my crimp tool), basic 1/4" flag quick disconnects fit the switches, and with some blades made for the other end of the splice, the switch works as normal.
(20AWG silicone insulated fit super easily):
Pile O Parts on top of an otherwise closed machine
