Maximum Overhang?

[jsondag]

Looks great. I'll have try this myself and see how few components it will take to make this measurement accurately. Does the 1.0 kit have any spare GPIO pins or are they all taken?

Would just take a charge resistor of high resistance, to charge the "capacitor", and a low value resistor to discharge.

The large resistance needs to be chosen to charge your capacitor slow enough to measure accurately, and fast enough to be responsive enough, and not be too affected by stray emf. This will depend on your build likely. I'd have to experiment to know a good time to shoot for.

200 ohms or something should be good for the discharge resistor.

if there are two free GPIO pins and enough free cycles on the built in micro on the peachy that's all you need. The firmware on the peachy could do that measurement and use it to correct for z-axis drift.

Or you can use a separate micro.
You can communicate with one free pin, or you could even read your dripper with the separate micro, and have it do some logic to insert or skip drips to correct for it's reading. That would require no changes to the peachy.

EDIT:
I lied, you need 3 pins. You'll need an analog pin straight onto the cap between the charge and discharge caps, to set a consistent point to trigger that the cap is charged. Digital pins aren't consistent in their trip point.

D0----~R1~--\
.....................|..............Jar
A0--------------|-----------| |------\
.....................|..........................|
D1----~R2~--/........................ GND





D0 goes high, which charges the Jar capacitor. A0 waits for it to hit a specific voltage, say 67% of supply. When it does, the micro counts how long that took, shuts off D0 (sets high impedence mode), then sets D1 low which discharges the cap. When A0 sees cap hit low (~5%?) D1 turns off (goes to high impedence).]

.... and loop