Running Arduino Firmware on a GOJO LTX-7 Soap Dispenser | Hacker News Reader

Running Arduino Firmware on a GOJO LTX-7 Soap Dispenser

github.com

47 pointsassttoasstmgr10 comments

AVRs are still pretty popular, and I think that predates the Arduino frenzy (starting about 2005). If you disassemble a bunch of devices in your house, you might find a few of these.

E.g. when I went to replace a faulty switch on my Logitech Perfomance MX mouse, I found an ATMEGA324PA. Debug pins seem to be exposed as well: https://steelcityelectronics.files.wordpress.com/2015/05/img... (not my site). But since I still use that mouse, I'd hesitate to flash the Arduino firmware on it ;-)

Another ICs for shenanigans of this kind: In smaller, bluetooth-enabled devices I usually expect to find a nrf5x these days (and FCC docs often allows pre-purchase clarification). I think both nrf51 and nrf52 are supported by Arduino and ZephyrOS. Bonus points, though I not yet tried that: Their firmware dumping protection seems to be faulty (though the nrf52 requires power fault injection), so reverting/modding could also be an option.

There are several neat projects floating around regarding these Nordic devices (most cheap Chinese smart watches have these too).

From my experience and he newer nrf52 chips are vastly more supported by software than the nrf51 ones.

I write firmware for nrf52 series chips. They are an absolute joy to work with. The sdks are well supported and there’s ample documentation/forums if you run into an issue.

I was hoping for some more subversive chicanery like making it pump erratically like it’s ejaculating into your hand to gross everyone out. :D

With a photo of Rudy Guiliani on the unit?

Well, the ground work has been laid out for you, so feel free to gross out your friends/family/coworkers/foes :P

For maximum creepiness, I recommend adding a small speaker. And a covert way to have it act perfectly normal, so you can say "it never does that for me" followed by a quick demonstration (most simple: have it misbehave with some chance, and then have it behave normally until a number of requests have been made or a timeout hit).

Here's a page with a picture of the soap dispenser this project works with: https://www.gojo.com/en-INT/Product/1388-04

Huh.. any idea if this would work on an LTX-12? I happen to have a couple (few?) hundred of them lying around..

It will work the same if the microcontroller is an Attiny48 and the ICSP header pins are exposed.

In addition to that it would also require same pinout for stuff connected microcontroller. If pinout differs then most of work will have to be redone anyway and it doesn't matter nearly as much whether it's Attin48, any other AVR microcontroller or maybe even completely different microcontroller as long as toolchain is reasonably available and easy to use.

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