Senseo coffee automation (ATtiny 85, SG90)

prusaprinters

<p>Third go at automating my Senseo coffee maker: turn it on, wait for it to heat up, pour a cup of coffee and turn it off again.</p><p>&nbsp;</p><p>First try was simple but hard to set up and not very reliable when pushing the buttons:</p><p><a href="https://www.prusaprinters.org/prints/110353-universal-button-pusher-sg90-mg996r">https://www.prusaprinters.org/prints/110353-universal-button-pusher-sg90-mg996r</a></p><p>Next iteration was robust and running for a couple of months; only drawback was slow speed for the steppers to turn the M5 pushing rods:</p><p><a href="https://www.prusaprinters.org/prints/110331-linear-actuator-stepper-pusher-28byj-48-m5-rod">https://www.prusaprinters.org/prints/110331-linear-actuator-stepper-pusher-28byj-48-m5-rod</a></p><p>This version of much faster and still reliable ;-) :</p><p><a href="https://youtube.com/shorts/s_PcQxmPolw">https://youtube.com/shorts/s_PcQxmPolw</a></p><p>Main features:</p><ul><li>Simple electronics based on a attiny85 and SG90 servos</li><li>Increasing force of servos with double threaded 8mm pitch about 20mm custom thread (pushing force &gt;10N measured)</li><li>Additional latching circuit court zero power consumption at idle</li><li>Electric setup: old phone battery with Tp4056 for charging, latching circuit from electronoobs (see source link below, with IRF9540N and 2N2222 as transistor drop in replacement), small boost converter 3.7V → 5V, actual attiny85.</li><li>Safety feature: program only starts if cup is in place (switch attached to machine)</li><li>Code for flashing attiny85 is included, it is Arduino based. I'm not a programming hero; I've derived it on the “useless machine” code from bra lark over at thingiverse</li><li>Small wiring writeup for attiny85: Pin 0: 1st servo, pin 1: 2nd servo, pin 2 safety switch (needs to be pulled low for “go”), pin 4: controlling latching circuit (needed to learn the hard way that pin 3 does not work for this… since it seems to be “high” on boot)</li></ul><p>&nbsp;</p><p>Source links:</p><p><a href="https://electronoobs.com/eng_circuitos_tut61.php">https://electronoobs.com/eng_circuitos_tut61.php</a></p><p><a href="https://www.thingiverse.com/thing:4561617">https://www.thingiverse.com/thing:4561617</a></p>