For better or worse it seems to be human nature to compete with one another, as individuals or teams, rather than experience contentedness while moving to the woods and admiring nature Thoreau-style. On the plus side, competition often results in benefits for all of us, driving down costs for everything from agriculture to medical care to technology. Although perhaps a niche area of competition, the realm of “smallest USB device” seems to have a new champion: this PCB built by [Emma] that’s barely larger than the USB connector pads themselves.
With one side hosting the pads to make contact with a standard USB type-A connector, the other side’s real estate is taken up by a tiny STM32 microcontroller, four phototransistors that can arm or disarm the microcontroller, and a tiny voltage regulator that drops the 5V provided by the USB port to the 3.3V the STM32 needs to operate. This is an impressive amount of computing power for less than three millimeters of vertical space, and can operate as a HID device with a wide variety of possible use cases.
Perhaps the most obvious thing to do with a device like this would be to build a more stealthy version of this handy tool to manage micromanagers, but there are certainly other tasks that a tiny HID can be put to use towards. And, as far as the smallest USB device competition goes, we’d also note that USB-A is not the smallest connector available and, therefore, the competition still has some potential if someone can figure out how to do something similar with an even smaller USB connector.
Thanks to [JohnU] for the tip!
Cool. One time insert. If you want it back you got to dig it out with tweezers.
LOL, no thanks
just wrap a piece of string around it
Which will be wrapped up by a fan or eaten by cat.
Maybe a plastic tab that you can tuck back inside.
I think one could prototype that idea with some kapton tape, but it might not have strong enough adhesive for multiple uses.
Doesn’t everybody want a rock to tie a piece of string around?
This would be epic for red-teaming. Tricky part is, how do you get it out of the USB slot?
The addition of a small hole in the PCB and a tiny hook of sorts would be my go to.
That’s the neat part, you don’t!
A few inches of dental floss wrapped around it before insertion?
Leave it long enough to get a good grip on and pull.
Maybe do a double loop and have it circle the board twice, so that you can even out the pull to keep it strait as you pull it out.
Much like the way battery compartments used to have a strap in them to leave underneath the cells and you pulled it to pop out the cells.
A tiny soldered wire pull string?
print a removal tool.
Take a good look at the picture it is possible to make a removal tool.
Non Destructive.
This exists. (Retail desktop support)
“USB type A security blocker with removal tool” So the tiniest USB just needs a tiny mod. Making it less tiny…
The link in the article states “Once inserted, it can be removed again by inserting any thin plastic tool into the port and pulling on the phototransistors.”
Any thin plastic tool that fits inside the slot and behind the phototransistors will do. I used tweezers but ofc you could also 3D print something to makes it easier
How about making it magnetic? Put it in with a sleight of hand a get it out with a reverse sleight.
Inserting anything into a type-A USB port requires more than a sleight of hand, at least in my experience.
Impressively small and with more components crammed on there than I would have guessed. The tiny 300 mA voltage regulator impresses me the most. I’m wondering what else could be squeezed in if the MCU was a WL-CSP package instead.
The awesome thing is, the vreg is a massive overkill – I don’t need even close to 300mA! Component miniaturisation is a wonderful thing
I’m not electrical engineer but wouldn’t a usb-c variant be… smaller?
if small was the game, why not start there?
Hey there, I didn’t start this project with the explicit goal of making the smallest USB device. My goal was to make a rubber ducky that couldn’t be seen from the outside and I only noticed after it was complete that it also seemed to be the smallest USB device currently around 😉
it wouldn’t, because you need both sides of the 0.8mm pcb then, so the components have to go on some extra area
[knotta] is correct in some ways. Just because you can’t fit the electronics inside the connector doesn’t mean it can’t be smaller than this project. Let’s say one were to make use of a smaller uC, and a double sided board with a USB-C edge connector, it could shave a few more mm of size for sure.
If I were to attempt it. I would first try using two flex-pcbs with components sandwiched in the middle. Pads exposed on the outside to make contact with the USB-C.
Getting everything the right thickness would be hard. If the radius of the bend for the flex-pcb is tight enough, then you could use a single pcb that is folded onto itself, providing the spring tension needed to maintain good contact without having to have such a tight fit, making it easier to pull out.
Myself, I can’t do it. I’d at least have to buy some microscopes to do the work because there’s no way I can look at tiny stuff for hours anymore.
Four photodiodes, for something meant to be INSIDE a contact?
Very impressive. My first thought was keylogger lol
The photodiodes have both a mechanical function (hold the PCB in place inside the port and maintain contact) as well as an electrical function (remote activation). I came up with the electrical function only after deciding I needed some sort of taller SMD component to use as a spacer. Ofc the range isn’t great but a surprising amount of light does get through
That’s really neat, thanks for providing the background.
Apparently a 3W IR source is needed at short distance (0.5 to 1m), so it barely works, but it works. A keylogger would need software on the device to send the info to the USB device.
https://hackaday.com/2022/01/01/genius-or-cursed-this-usb-c-connector-is-flexible/
smaller?
ideal for tox node or onion tor or reticulum
2 words that will make you cringe: wireless USB
I’m probably just missing the point (and I suppose making something small is fun in and of itself), but why have a connector on something you can’t remove again at all? If you’re building a one-time insert USB device, why not just put it inside a usb c cable’s connector like you already get with things like the usb pd cables that have a little OLED screen that tells you the voltage and current being drawn? Or like how lightning cables used to do some conversions or some weirder converters..
If you want it to be stealthy and pass-through you can just add a usb-c port at the end of it. So it is just a usb-c cable. That way there isn’t even a suspicious little board blocking the port.
It isn’t stuck in the port, you can remove it quite easily and without damaging anything using any small plastic tool that fits in the port 😉
what jumps to my mind is enhancements for laptops. if you don’t have or can’t use an internal like M2 sort of connector then the USB is handy…but you don’t want a big dongle or cable hanging off of your laptop if it ever actually leaves your desk. so this fits the bill nicely. and the market has already produced usb bluetooth dongles that only stick out about 4mm…bigger than this device (and easier to remove), but just barely.
of course i don’t know too many devices that are useful and happy inside a usb connector. even the bluetooth dongles seem to get lousey performance as a compromise for being mostly encased in the shielded connector. (?)
geez. how’d there get to be so many rude, dismissive complainers on here?
Reminds me of the USB-A version of the Yubikey Nano.
Perfect for pranking stores. Stick one containing the file of Rick Astley’s Never Gonna GIve Up video and had it sit and do nothing for a few hours (tri-state D+ and D- pins) and wait x minutes or hours since power on, then connect the pin, behave like an USB storage, and offer video file. Most TV often auto plays video file if there’s only one.
I feel like there is a lego made for removing this.