Hacking Washing Machines [video]
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Diving into the fascinating world of appliance hacking, a recent video presentation revealed the inner workings of modern washing machines, sparking a lively discussion around their diagnostic communication methods. Commenters were intrigued by the use of acoustic signaling, with some noting that LG appliances employ a 4-tone frequency-shift keying method for diagnostics, while others pointed out that this approach may be a form of "gatekeeping" that ties customers to manufacturers. The conversation also touched on other devices using similar signaling methods, such as electric meters with blinking LEDs, and infrared interfaces for bidirectional communication. As the discussion unfolded, it became clear that the intersection of appliance design and communication protocols is a rich area of exploration, with implications for both security and user experience.
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The optical communication for the Miele was pretty interesting too. I'm assuming it's to prevent moisture from corroding a port of some kind. Does anyone know of other devices this is used in or other benefits to this?
The primary value discussed in the talk was electrical isolation since there's mains voltage in the appliance and the potential for shorts or inadequate isolation would require some kind of isolation, so a path that optically isolates the communication makes quite a bit of sense.
I'm also curious if other devices have gone this route.
[1] https://github.com/kabelincho/LG-Smart-Diagnostics-modem
All the same diagnostics you can do at the machine, the phone home service allowed a remote engineer to diagnose as well. Things like drum rpm, tilt/knock sensors, uneven balance detection. Instead of paying a human $250 to come out and press buttons, they can do it remotely.
I understand in the pessimistic age of John Deere, all remote diagnostics are bad, but that is not the case here. I was able to do all of the diagnosis myself to determine it was a bad stator and then replace it myself.
Decoding it without help would be difficult for the average consumer, but it's not an impossible task.
Do you mean by mimicking the noises themselves?
https://en.wikipedia.org/wiki/Blue_box
https://en.wikipedia.org/wiki/IEC_62056
We have a Miele washing machine and a Miele dryer. Solid machines all around even after years of use.
The usual solution here is an optical coupling of some kind - optocouplers (a box with a LED, photodiode, and air gap between them) are very common for this purpose, and are an inexpensive and effective option for digital signaling across an isolation boundary.
In this case they’ve basically built a custom optocoupler out of discrete components, which is a bit unusual, but makes sense when you consider the risk of corrosion due to water ingress at the diagnostic ports, and the need to access it while - for example - a dishwasher cycle is running.
https://gemini.google.com/share/8da7ecf202d8
TL:DR; the circuitry could be powered by 5V, but to save costs that 5V is 5V difference to 110/220V, not 0V (earth). Connecting a computer would create a 110/220V difference between the ground of the machine's circuitry and the computer's...
IRDA was very popular at one point and still lives on in applications like these. It's an IR serial port hung off a UART. It's stupid simple requiring no cables, pairing, or complex protocol stacks. Some smart phones have IR blasters built in so its a total win for ease of deployment in cases like these.
Latching relays/(technically solenoid) could be driven on/off fast, the downside is in a power cut or an emergency, the relay wouldn't release unless specifically driven so.
So the third option is a momentary solenoid, which would need to be powered the whole time the door is shut, and they require a surprisingly significant amount of power. Typically 10-20w. Negligible when it compares to the KW+ heating elements, but they do add up for the energy ratings..
Fwiw, I currently have a haier, which does have one of the second options, and opens immediately after a wash and it's amazing. Can't go back.
But, wax motors continue to be used because they're just the right tool for the job.
"I'm sorry Dave but I'm afraid I can't do that"
Perhaps that doesn't apply to you and how your home is set up. Fair enough. But that doesn't mean the use case doesn't exist.
Of course I would never, ever give devices like this access to the 'net, not even for a few seconds. What 'smart' devices I have around usually run firmware which I installed on them, replacing whatever leaky spyware they came with from the factory. The only exception to this rule is the Fronius inverter which runs its original firmware but just like all other 'smart' things it lives in its own enclave and never got a single bit from or to the 'net. All communications goes through proxies which are under my control, there are no automatic firmware upgrades, no information leaks, no nothing - we live on a farm in the Swedish countryside so there is chance for any 'smart' device to surreptitiously hop onto an open WiFi-network either. Maybe I'll have a look at adding some ESP32-powered wifi functionality to the washer and dishwasher so I can integrate them into the (OpenHAB-powered) control system I use for controlling all things electronic here, something to do for a snowy day?
In the meantime, I'll leave this here:
https://github.com/medusalix/FreeMDU
The WiFi implementation was interesting to me, I am glad that it is reasonably safe. I understand much of the skepticism around these kinds of features, but I also see the value in many settings. As long as they remain optional, I think the benefits outweigh the drawbacks. Kudos for BSH having good developer documentation and a local mode. I feel like a local mode should be mandatory, for safety and support reasons
A few other interesting tasks I was involved back then were:
- smashing an oven's door until the hinges would give up - testing new heating elements in the open (basically, building a gigantic grill) - appliance transport packaging tests - cooking and baking on a daily basis to make sure food turns out as expected
Overall, home appliances are a great product as an engineer to work on. It is a product you usually use multiple times a day. And if you love cooking yourself, even better :-)
It has been working for 25 years with no servicing, except when it "broke" once about 5 years ago. So I just opened it, stared at it for a while, and after considering the symptoms (no click in the door locking mechanism but power indicator light turning on), I realized the issue will be with something very early on in the fixed washing cycle, before the timing motor gets activated, and there will be no serious electrical damage elsewhere (fuse intact). So I looked at the door locking mechanism (bi-metalic thing) and noticed that the cable connector leading to it was slightly shifted. Re-seated the connector, and the machine started working again.
While it was open, I didn't notice anything horrible (corrosion, leaks, nothing). Probably the next thing that will "break" will be when the motor's carbon brushes will "run out". :)