[bri3d]

LG appliances at least used to use acoustic signaling for diagnostics: hold a phone up and the washer makes some modem-esque (I think it’s 4-tone / 4-FSK) noises and the app or technician can diagnose issues. It was originally engineered to even work over voice codecs, so a customer without a smartphone could relay the diagnostic session to a technician.

[atoav]

The absolutely "leetest" thing I have ever seen was a device where the firmware update was to be done by:

1. Hold a button while booting (pretty normal)

2. This reconfigures the circuit path of one of the LEDs so it is reverse-biased to VCC via its resistor and switches one of the microcontroller GPIOs to ADC input

3. You go to a website that plays a strobe pattern (encoding the firmware)

4. You hold that website in front of the LED till other LEDs blink, signifying a successful update

They could have done this using a photodiode, but no, they had to abuse an LED. Not many people are aware that LEDs can in a certain configuration be used to measure light.

[nicolaslem]

Another example of firmware update reusing something that is already there: some electric guitar effects from TC Electronics can be reprogrammed by bringing a phone close to the guitar pickups. The phone app encodes the data as sound that is picked up by the guitar pickups and sent down the chain to the effect.

[atoav]

Ahh good example I remember having done that myself before!

[opello]

That's pretty cool. I found a write-up[1] on it but unfortunately didn't come across any examples of the communication.

[1] https://github.com/kabelincho/LG-Smart-Diagnostics-modem

[bri3d]

There are lots of examples on YouTube, this one seems succinct: https://youtube.com/shorts/3Eb315vL9uw . They picked good tones to make it satisfying IMO. I don’t know of anyone who’s reversed the bitstream in public, though, but it doesn’t seem like it should be very hard.

[opello]

That's a great example, thanks! I was looking for "LG Smart Diagnostics" and "audio" and then "LG Acoustic Diagnostics" and found TVs calibrating their audio playback but not this. Trying "LG Audible Diagnosis" found a bunch like yours.

[imglorp]

That's some advanced gatekeeping right there. Where other appliances might have a blink code or several digit error display (Miele) to look up in a manual, the phone method tires you to the manufacturer.

[noAnswer]

The support hotline will ask you to hold your phone towards the device. It is less error-prone (than a human) and contains more info than a blink code. I find it really clever.

[imglorp]

Sure it's clever. But it also means you can't repair the appliance without the manufacturer's server to decode it for you.

[grepfru_it]

Owner of an LG washer that failed here.

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.

[yhager]

How were you able to diagnose it yourself? Just through the error codes, or is there another interface available for non-technicians?

[grepfru_it]

You enter diagnostic mode on the panel, there exists a service manual which describes the process

[thesuitonym]

It doesn't require a server, it just requires knowing what the codes mean, same as blinking lights.

Decoding it without help would be difficult for the average consumer, but it's not an impossible task.

[landr0id]

>so a customer without a smartphone could relay the diagnostic session to a technician

Do you mean by mimicking the noises themselves?

[wpm]

No you see you just need to buy specially marked boxes of Cap'n Crunch that have a plastic whistle in them that plays the tones for you.

[userbinator]

I wonder how many HN readers still get that reference (and 2600, etc.)

[Y_Y]

I'm merely middle aged, but I've read the hacker lore.

https://en.wikipedia.org/wiki/Blue_box

[hunter2_]

We make use of a service already existing without paying for what could be dirt-cheap if it wasn't run by profiteering gluttons...

[notpushkin]

By holding their phone up to the machine.