RE: USB Keypad

[<dave@synergy.org>]

Greg,
	Wisdom, indeed. I just disconnected the keypad from the Pi and
connected it to my Windows laptop. When I brought up an editor I was able to
demonstrate exactly the same mappings. No, it is not the kernel. This
appears to be the device, itself. Thank you for the debug suggestion. I
should have thought of it.
	Thanks,
	David



-----Original Message-----
From: Greg KH <greg@kroah.com> 
Sent: Monday, July 6, 2026 9:30 PM
To: dave@synergy.org
Cc: linux-usb@vger.kernel.org
Subject: Re: USB Keypad

On Mon, Jul 06, 2026 at 08:08:01PM -0700, dave@synergy.org wrote:
> Excuse me. I have never sent e-mail to the Linux Kernel mailing list
before.
> In reading the protocol, I think I should have sent my message to this 
> one, instead.
> 
> Hello,
> 	I am working on a mobile device based on Raspberry Pi OS. I am using

> a USB keypad to navigate the UI of my device. I have purchased 2 
> models. One has 19 keys and the other has a few more. I've implemented 
> the user-space code to read() the input device. Things are generally 
> working fine. But I have one issue. On both models the keycodes I 
> receive are not unique across all keys. On one, the key labeled INS 
> and the one labeled 0 both send the same code.

That sounds like a broken device, not much the kernel can do about that.

Can you confirm this by looking at the keycodes when plugging the device
into any other "normal" Linux system?

> On the second one, the mapping is even more bizarre. It has duplicated 
> Num Locks and other keys, as well. The number keys are always readable 
> as such, but the other non-number keys can be aliased.

Again, is this keyboard issue?  Do they work properly anywhere else?

thanks,

greg k-h