I like challenges, and I also like smart devices, what we usually call “gadgets.”
What do I miss in my washing machine? Notifications to let me know when it is done washing my clothes. Yes, some models play a catchy little tune to make it clear that they are done, but not mine… Even if I had one of those singing washing machines… What if I’m listening to music with headphones? What if I am upstairs? Well I will have to be checking every little bit. Also, the washes are somewhat flexible in wash cycle duration (they do not have exactly X minute wash cycles, since depending on the clothes you are going to wash, it will be easier or more difficult to evacuate the water). I usually use the 60 minute wash cycle, unless the clothes are really very dirty, but the real time in my case is actually 63 minutes one day, maybe 75 the next…
Tired of this, I have decided to open my washing machine and figure out some way to detect when it ends, in order to launch a notification to my phone. And if I can make it possible to activate the wash cycle remotely at the same time, that would be even better (my poor low-cost washing machine does not even have the function of deferring the start of the washing cycle by X hours …).
Well… where do we start? Opening the top case, so let’s find a screwdriver. In my case, the screws were not typical phillips screws: they had 6 points instead of 4 (torx screws), so the first thing I did was search among my tools for a screwdriver or a suitable tip.
Three screws later, and I have access to the guts 🙂.
At this point I had already thought that the best way of detecting when the washing cycle is completed could be checking the state of the door lock, since the door keeps locked while the washing is in progress, and unlocks once it has ended. So, with a flashlight at hand, I started tracing the wires that lead to the lock, finding these three:
To investigate which cable did what, I stripped part of the insulation of the three wires, and using my multimeter, I started measuring voltages. What I found was:
- Black wire: Between it and neutral, it measured 230v once I chose any washing program (even before starting it, without pressing the start button).
- Blue wire: Between it and neutral, it measured 230v once the door was locked (it takes about a second or two since the start of the washing cycle).
- Red wire: Between it and neutral it didn’t measure voltage. As this is the last one, it must be neutral.
The washing machine brains seems to send 230v over the black wire once a program is selected, connects the red wire to neutral once the washing cycle starts and waits for the blue wire to continue, meaning that the door has been locked.
I will need a direct neutral to power the microcontroller as soon as the machine brains are powered, so I ended taking it directly from the main neutral wire, and isolated the red wire (with regular tape… I didn’t have proper electric tape… professionalism over all 😊) and extended the three cables we were going to use (this last neutral, the black wire, so the live wire, and the “locked” signal, the blue wire, that will let our microcontroller know the state of the door).
With this, I left the machine ready for the future. When I have the microcontroller ready, it will be an easy task of just connecting it 😉
I put the top case back again (I needed to keep using the washing machine after all…) and started thinking of the microcontroller unit, which I will tell you about in the next post! 🙂.