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Ask HN: Advice for creating a USB device linking 2 computers

20 points WorldDev | 7 comments | 25 Oct 25 19:01 UTC | HN request time: 0s | source | bottom

I want to build a little device that connects two computers together via usb, and send keystrokes from one to the other.

(I would use it to use a laptop keyboard on a headless computers).

I am looking for an easy solution, it does not have to be the cheapest.

ChatGPT points me to Arduino, but as far as I can see, there's no arduino with 2 usb ports. It also points me to Raspery pi zero, but that's a computer, not a microcontroller, so not sure if it's suitable.

If anyone with experience can give me some pointers, it would be greatly appreciated!

1. simondanerd ◴[25 Oct 25 19:21 UTC] No.45706288[source]▶
Sounds like a cool project, but you may find that using SSH or RealVNC to be a bit easier and cheaper.

ChatGPT isn't wrong - this sounds like what you need: https://pypi.org/project/zero-hid/.

replies(1): >>45706500 #
2. WorldDev ◴[25 Oct 25 19:53 UTC] No.45706500[source]▶
Thanks for your thoughts. I agree that using software would be easier, but I wanted to do it in hardware in this specific case.

I am unfamiliar with Raspberry pi, but if my understanding is correct, it's running a real os. So I would need to send it a command to actually shut down every time I want to remove the usb device. More generally, having a general purpose OS on the little device seems overkill for that use case, no?

replies(2): >>45706564 #>>45706573 #
3. simondanerd ◴[25 Oct 25 20:04 UTC] No.45706564[source]▶
It usually runs a Debian based image. And you would probably just have to reboot the script, or write a wrapper around the keyboard functions.

But yes, it's overkill for an overkill solution. Buying another keyboard may be easier.

4. throwaway81523 ◴[25 Oct 25 20:05 UTC] No.45706573[source]▶
I'm confused, why do you want hardware and what do you want the hardware to do? And, why not use a USB keyboard?

You could use an rpi pico. It has a usb port and there is a software hack to bit bang a second usb port, iirc.

replies(1): >>45706592 #
5. brudgers ◴[25 Oct 25 20:08 UTC] No.45706592{3}[source]▶
I am wondering if connecting over USB is an XY problem.
replies(1): >>45706928 #
6. WorldDev ◴[25 Oct 25 21:01 UTC] No.45706928{4}[source]▶
To try and clarify a bit: I am essentially trying to have a KM (KVM without the V) over USB.

To go one step higher, I am trying to control a mac mini from the keyboard of a macBook.

replies(1): >>45707235 #
7. brudgers ◴[25 Oct 25 21:43 UTC] No.45707235{5}[source]▶
Why not use the macs’ built in “sharing” functionality?