DIY 'Smart' Coffee Maker

William Floyd — Sun, 05 Jul 2020 00:00:00 +0000

I have recently (last couple months) been getting into home automation, specifically using Home Assistant. I also wanted to get a coffee maker that used K-Cups. Thus the goal was born - to get a coffee maker working with Home Assistant, such that I could automate it to fit my morning routine.

I first searched for new coffee makers, looking to see what the easiest ones would be to hack into and automate. I got so far as adding a sleek new brand name model to my Amazon cart, but thankfully reason and frugality prevailed! Instead, I opted to swing by the local Goodwill the next day, to see what secondhand options might be available. As luck would have it, I found a no-frills, single button coffee maker for the princely sum of $4, and I was on my merry way.

Later that evening, opening the black box up (thankfully I had the correct triangular screwdriver head), I found very easily hackable innards.

The control board (front, back) is very simple - two buttons in parallel, an LED, and a couple resistors. I’m not quite sure what the logic is upstream (it un/latches on each press), but the buttons short to ground, and this is something I can work with. The control board has wires for ground, signal, and 5V, in that order.

The ordeal of hacking into the thing, and my missteps trying to do so, is rather boring really, but it produced this:

The brains I added was a Wemos D1 Mini (thanks, Aliexpress!), with a 3.3V<->5V converter between to sense when the coffee maker is on, and also turn on a mosfet to short the button to ground. I initially had issues with the coffee maker turning on whenever I plugged the D1 Mini in, but a pulldown resistor solved this.

I also opted for an external USB plug - this allows me to possibly reflash this without opening the enclosure, and also meant I did not need to splice into the mains line inside, which I was reluctant to do.

I initially flashed and programmed the coffee maker with Tasmota, but almost immediately opted to use ESPHome instead. I like Tasmota and ESPHome, I was just able to get more fine control of the setup using ESPHome in this instance, especially concerning the button logic.

The (important) code is as follows:

binary_sensor:
  - platform: gpio
    device_class: power
    internal: true
    id: power_on
    pin: D2
    
switch:
  - platform: gpio
    pin: D1
    id: relay
    restore_mode: ALWAYS_OFF
  - platform: template
    name: "Coffee Maker"
    icon: "mdi:coffee-maker"
    lambda: |-
      if (id(power_on).state) {
        return true;
      } else {
        return false;
      }
    turn_on_action:
    - switch.turn_on: relay
    - delay: 50ms
    - switch.turn_off: relay
    turn_off_action:
    - switch.turn_on: relay
    - delay: 50ms
    - switch.turn_off: relay

The beauty of the way in which I can detect signals and simulate a button press is that ESPHome senses when I use the physical button, and updates accordingly. I can use the coffee maker absolutely as normal, the ‘Smart’ part of it is optional.

The rest of my setup using this coffee maker is somewhat outside the scope of this post, but it includes using Tasker on my phone to run a ‘Wakeup’ automation on Home Assistant, which will - along with turning on my bed-head lamp, and switching my monitor on before putting it to sleep - check if I turned on a ‘Morning Coffee’ user input. If I remembered to prep my coffee the night before, and turned on the switch, I will wake up to a hot cup of coffee (or, the sound of a coffee-in-progress). I can also command Alexa and Google Assistant to do my bidding and make me a coffee. At least someone does what I want…

Truly, we are living in the future.

midiMixer - A simple Arduino powered MIDI potentiometer bank

William Floyd — Wed, 06 May 2020 00:00:00 +0000

This is nothing too special really - I wanted to try my hand at designing a custom PCB and assembling a device from scratch. GitHub for this project.

This story actually starts a while ago (perhaps 2015), when I got the desire to build a DJ control panel (with no knowledge of how to get into it). This never really happened, but it did lead me to get to know some DAW software, and experiment with it off and on. But in the back of my head I still wanted to build some hardware to help with this.

This eventually came about in the summer of 2019, when I finally hand-wired a simple 8 knob control surface. Truth be told, I actually built two. The first one had some issues (I wonder why…?), and would sporadically jitter values. The second one worked correctly, having been wired much more carefully.

Still, it was lacking professionalism, polish, and most importantly, robustness. The sandwich of 22AWG wire, cardstock and PCB was less than sturdy, so I promptly packed it away and never used it. Around this time also, I tried very briefly to learn how to use KiCAD, but didn’t get far at all. This would come to change, however, in April of 2020.

Fast forward close to a year, and here we are - toilet paper is the currency of the quickly collapsing Covid19 crazed world, and I’m back with my grandparents for the remainder of my semester (which, as of writing, is all but concluded). Finding my lack of a social life leaving me with a little bit more free time, and being home yielding a lot more distractions, I learned the basics of KiCAD from YouTube, and set out to design a simple PCB. My old MIDI controller project came to mind, so I set myself to it, and within a few days had my first Gerber files sent off to JLCPCB. In reality, I should have waited a bit and done a couple more design iterations before committing, but I guess $7 is the price of impatience.

So it was that my crisp PCBs showed up 3 weeks later - I had one assembled within the hour, and my old code dusted off and flashed within two hours. It’s really as simple as it gets - a Pro Micro hooked up to a 4051 analogue multiplexer, in turn hooked up to 8 potentiometers.

The potentiometers I had on hand ended up being a bit different than the footprints I had used, so I ended up having to clip the mounting tabs off of them. This, as one might imagine, made them extraordinarily flimsy, so I designed and printed a couple clamps to align and hold solid the potentiometers. These also have the added benefit of keeping the soldered pins off of whatever surface the mixer is on. Should the correct potentiometers be used, these would not be needed, though some feet or a case for the PCB would still be best.

This being my first PCB design, I am quite happy it worked out so well - I am studying for Mechanical Engineering, not Electrical… However, I see room for improvement. The potentiometers are too close together, and the rows are too far apart. The knobs barely clear the Arduino, and the Arduino is mounted far higher off the PCB than I would like. I see myself making a v2 in due course - perhaps next time I will try JLCPCB’s SMT assembly? I imagine adding indicator LEDs, improving the layout, and adding a button to switch between banks would make this much more useful.

Hobby on William Floyd (high-quality images)

DIY 'Smart' Coffee Maker

midiMixer - A simple Arduino powered MIDI potentiometer bank