USB Keypad

USB Keypad

[dave]

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. 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.
	My question is simple: is there something I need to do to change the
mode of the keypad to send unique codes? Perhaps an ioctl()? I do not know
the HID spec. I wonder what pressing the Num Lock key causes an OS (like
Windows) or X11 to do to change keypad modes. Is there a document or website
I can read that discusses this?
	Thank you,
	David

Re: USB Keypad

[Greg KH]

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

RE: USB Keypad

[dave]

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

USB Keypad

[dave]

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. 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.
	My question is simple: is there something I need to do to change the
mode of the keypad to send unique codes? Perhaps an ioctl()? I do not know
the HID spec. I wonder what pressing the Num Lock key causes an OS (like
Windows) or X11 to do to change keypad modes. Is there a document or website
I can read that discusses this?
	Thank you,
	David

USB Keypad

[Josh Litherland]

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I want to simultaneously use a PS/2 keyboard (This is a laptop, so
switching that out is not an option) and a USB numeric keypad, which 
works perfectly as a usb HID keyboard.  Is there any way to do this
with the current keyboard driver ?

-- 
Josh Litherland (fauxpas@temp123.org)
public key: temp123.org/fauxpas.pgp
fingerprint: CFF3 EB2B 4451 DC3C A053  1E07 06B4 C3FC 893D 9228

[-- Attachment #2: Type: application/pgp-signature, Size: 240 bytes --]

Re: USB Keypad

[Greg KH]

On Thu, Jul 18, 2002 at 09:52:32PM -0400, Josh Litherland wrote:
> I want to simultaneously use a PS/2 keyboard (This is a laptop, so
> switching that out is not an option) and a USB numeric keypad, which 
> works perfectly as a usb HID keyboard.  Is there any way to do this
> with the current keyboard driver ?

Should work just fine today.  What kind of problems do you have when you
try to do it?

thanks,

greg k-h

Re: USB Keypad

[Josh Litherland]

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On Thu, Jul 18, 2002 at 08:10:00PM -0700, Greg KH wrote:

> Should work just fine today.  What kind of problems do you have when you
> try to do it?

Just not getting any events from the keypad.  When I load up evdev, and
cat the device I get the appropriate gibberish, so the device is
detected okay.  This is 2.4.18, if that makes a difference for the
purposes of this discussion.

-- 
Josh Litherland (fauxpas@temp123.org)
public key: temp123.org/fauxpas.pgp
fingerprint: CFF3 EB2B 4451 DC3C A053  1E07 06B4 C3FC 893D 9228

[-- Attachment #2: Type: application/pgp-signature, Size: 240 bytes --]

Re: USB Keypad

[Greg KH]

On Thu, Jul 18, 2002 at 11:20:08PM -0400, Josh Litherland wrote:
> On Thu, Jul 18, 2002 at 08:10:00PM -0700, Greg KH wrote:
> 
> > Should work just fine today.  What kind of problems do you have when you
> > try to do it?
> 
> Just not getting any events from the keypad.  When I load up evdev, and
> cat the device I get the appropriate gibberish, so the device is
> detected okay.  This is 2.4.18, if that makes a difference for the
> purposes of this discussion.

If the device is detected, how is it detected?  Is the USB HID driver
binding to the device?

thanks,

greg k-h

Re: USB Keypad

[Greg KH]

On Thu, Jul 18, 2002 at 11:30:05PM -0400, Josh Litherland wrote:
> On Thu, Jul 18, 2002 at 08:24:45PM -0700, Greg KH wrote:
> 
> > If the device is detected, how is it detected?  Is the USB HID driver
> > binding to the device?
> 
> hub.c: USB new device connect on bus1/1, assigned device number 4
> input0: USB HID v1.00 Keyboard [        USB Keypad                    ] on usb1:4.0

Looks good to me (from a USB subsystem standpoint.)  As for why it's not
working for you, I don't know.  Perhaps it's spitting out keycodes that
you're not expecting to see.

Good luck,

greg k-h

Re: USB Keypad

[Brad Hards]

On Fri, 19 Jul 2002 13:20, Josh Litherland wrote:
> On Thu, Jul 18, 2002 at 08:10:00PM -0700, Greg KH wrote:
> > Should work just fine today.  What kind of problems do you have when you
> > try to do it?
>
> Just not getting any events from the keypad.  When I load up evdev, and
> cat the device I get the appropriate gibberish, so the device is
> detected okay.  This is 2.4.18, if that makes a difference for the
> purposes of this discussion.
OK, evdev is on the userspace side of the input core (and USB is on the other).
If evdev reports events (and you can decode them, if you are interested, using
tools available from the linuxconsole CVS), then all is probably well with USB and
the input core.

The obvious error would be not compiling in the input layer keyboard driver (or
not loading the module, whatever). 

If that definately isn't wrong (like lsmod shows the module, or a normal USB
keyboard works fine and the keypad doesn't), then we'll likely need the 
HID descriptors. Probably easiest to get them from evdev using the evtest
tool from linuxconsole CVS.

Brad

-- 
http://conf.linux.org.au. 22-25Jan2003. Perth, Australia. Birds in Black.

Re: USB Keypad

[Josh Litherland]

On Fri, Jul 19, 2002 at 01:36:02PM +1000, Brad Hards wrote:

> The obvious error would be not compiling in the input layer keyboard driver (or
> not loading the module, whatever). 

Good call.  That did it, thanks.

-- 
Josh Litherland (fauxpas@temp123.org)
public key: temp123.org/fauxpas.pgp
fingerprint: CFF3 EB2B 4451 DC3C A053  1E07 06B4 C3FC 893D 9228