Re: How to connect USB keyboard to embedded device?

On Sat, 16 Jul 2005 02:15:34 GMT, CBFalconer <cbfalconer@xxxxxxxxx>
wrote:

>Well, color me stoopid, but I fail to see any reason somebody wants
>to use a complex USB system, with attendant reliability, protocol,
>and maintenance problems at both ends, rather than the simple, well
>tested, readily available PS2 interface for a keyboard.

I'd much rather support a PS/2 or standard AT keyboard connector.
However, as you may have noticed, the old larger-diameter AT keyboard
connector type keyboards are getting harder to find. Especially new.
A *lot* of USB keyboards, some PS/2 -- and a few of the PS/2 ones will
include one of those adapters in them for the old connector.

Where does one buy an ISA bus system anymore?? And I like them for
building protos of my own. I don't have the ability to work with PCI,
as reflection wave bus design with 1 and 2 nanosecond clock to data
skews, etc., are out of my hobbyist league. Plain and simple.

I guess these things are why I didn't question the OP's direction and
instead took it on face value and went with it.

>You will have no problem finding PS2 keyboards for 2 to 3 USD at
>your local Salvation Army or Goodwill store. Other countries may
>need to look elsewhere, but they should still be more easily found
>(and cheaper) than USB keyboards.

But for how long? Do you know where to go to get an ISA floppy disk
controller? Or an ISA hard disk controller? Or one of those
multi-I/O controllers for the ISA? I've got them still in boxes here,
but there is no way I could source one commercially, these days.

When planning products for long term availability, I can understand
someone desiring to look at the current situation and extrapolate a
bit to see what is changing and to plan for it. At least, within
reasonable bounds.

The question, I suppose, is whether or not planning in a USB keyboard
connector is within reason. There probably would be no argument from
you or others, were it the case that USB hosting was easy to do. The
only reason there is an argument here is simply because there are real
risks and so folks quibble over that choice in the context of various
alternatives. Ultimately, the OP is going to have to decide. All we
can do is kibitz.

Jon
.

Relevant Pages

  • Re: keyboard problem with 2.6.6
    ... > If an application wants to access directly the keyboard, ... > provides some kind of interface for driving directly USB devices. ... reason using PS/2 protocol to talk to the kernel. ... > interface to keyboards without raw mode. ...
    (Linux-Kernel)
  • RE: keyboard/mouse not working
    ... If you have a USB mouse and keyboard and the setting in bios disabled the USB ... for some reason (ie. daughter messing around in there) then the mouse and ...
    (microsoft.public.windowsxp.help_and_support)
  • Re: Keyboard stop working unexpectedly
    ... The old keyboard used a PS/2 and the new one uses USB. ... restart PC to get working keyboard for several minutes. ... Any one have any idea what can be reason of this troubles? ...
    (microsoft.public.windowsxp.hardware)
  • Re: Hello
    ... is just an upgrade and even if will do so will be with a lot of bugs. ... So better you will install a fresh installation of windows xp. ... USB ... keyboard wouldn't load until after the OS loaded. ...
    (microsoft.public.windowsxp.basics)
  • Re: Supporting a PS/2 Keyboard
    ... I don't have any USB to PS2 ... The NOP keyboard ... One alternative then is to get the hardware guy to put a PS/2 to USB ... I assume that CE's USB HID driver supports a USB ...
    (microsoft.public.windowsce.platbuilder)