Re: [CAD_CAM_EDM_DRO] Linux USB Support -- Second Keyboard (pendant)

carl@... wrote:

> Do newer versions of Linux (than the BDI EMC install) have
> better USB support? Which version would be stable and provide
> USB support?

The stock 2.2.19 and all 2.4.x Linux kernels have USB support
(although I'll note there is a different kernel USB project from the
user USB project -- _long_story_). Most Linux distributors (see
list of RedHat releases below) started merging the USB backport
(from 2.4 to 2.2) as early as kernel 2.2.16 (e.g., in RedHat's 6.2
updates). Linux understands any well documented device types.
Keyboards, mice, ACM modems (only about 25% of USB modems follow the
ACM command set) ... although, as with anything in Linux, any device
that has documentation (which is up to the manufacturer) will
usually be supported within 6 months of release (faster if the
manufacturer is involved).

[ Side note: If you don't like the lack of hardware support in
Linux, don't blame the Linux developers, blame the hardware
vendors. God knows Linux developers themselves write 100x as many
drivers for Linux than Microsoft themselves writes for Windows. ]

The "larger problem" with USB is that it was designed by two
companies so there was _minimal_ effort on the controller
*COUGH*Intel*COUGH* and the root hub driver
*COUGH*Microsoft*COUGH*. That's why it took 3 years to get devices
out, why many devices (especially when you use 3+ other than just a
KB/mouse) will "conflict" with each other on the same USB channel,
especially on non-Intel USB hubs. This is because, again, USB is
designed as simple serial bus, analogous to RS-232, and not an
interface with a full command set, analogous PC serial UART.

[ Side note: If you don't like this, then blame Intel and
Microsoft, the "two goons" behind USB. God knows I'm
_cursing_them_now_ writing a USB Wireless LAN (WLAN) driver! ]

I could start a tangent on IEEE 1394 Firewire and Intel's renigging
on putting it in the southbridge, as well as the _folly_ of USB 2.0,
but I won't. ;-PPP

BTW, I'm new to all this stuff, so what are common interfaces?
Serial/UART? GPIB? other?

> I want a pendant to control my mini-mill. I have disassembled
> a USB keyboard, removed the electronics parts and hacked
> together a box with a few buttons and such. Works fine under
> WinDoze, just thinks it's another (second) keyboard.

Cool. Of course you can also do that with your regular PS/2
keyboard. Although the different is that your "extra" USB keyboard
has been assigned a device number, which you can "target"
independently of each other.

Of course, I've seen a _lot_ of bus with the keyboard API and
general USB bus reaction. I have used multiple keyboards, keypads,
etc... and seen the whole USB bus toast. And I think there was just
a bug announcement where Win2K can hang on USB keyboard errors
(which might not plague just Win2K)?

> Can I get this to work with EMC? I don't have a problem
> compiling a kernel or EMC to get the right versions.....

I gotta get familar with this LinuxCNC schtuff.

I take it you can install one of two ways (at least the Penguin CNC
release):

- Stock RedHat distro and then add the RTLinux and EMC schtuff

- Penguin CNC BDI (brain dead install) which is an image of a
working installation (and needs to be customized)

BTW, here are the kernel versions for different releases of RedHat's
Linux:
CD Updates*1*
-------- ---------
RedHat 6.0 2.2.5 2.2.19*
RedHat 6.1 2.2.12 2.2.19*
RedHat 6.2 2.2.14 2.2.19*
RedHat 7.0 2.2.17* 2.2.19*/2.4.3*
RedHat 7.1 2.4.2* 2.4.3*
RedHat 7.1.93*2* 2.4.6* n/a
RedHat Rawhide*3* 2.4.7* n/a
Latest Linus kernel 2.2.19/2.4.9

Notes:

* Has native USB support, or merged in backport. Note that 2.2.x
kernels don't have a complete USB subsystem like 2.4.x.

*1* RedHat Updates & Errata can be found here (I recommend you get
on the mailing list too):
http://www.redhat.com/support/errata/index.html

*2* This is the first RedHat 7.2 "beta" called "Roswell" (yeah, many
of us thought it was a joke too ;-). It sports the first RedHat
distro with a journaling filesystem (Ext3). I will *NOT* get into
the various journaling filesystems for Linux, but if you are
interested, check out this presentation I did on them:
http://www.smithconcepts.com/files/presentations/ITEC_JFS_2001Jun13.pdf

*3* Rawhide is a "dumping ground" for new RPMs that have not been
fully tested (even though the software themselves might be full
releases by their respective projects)

Local mirrors of RedHat's archives can be found here:
http://www.redhat.com/mirrors.html

Okay, I'll stop "babbling" now. ;-PPP

-- TheBS

--
Bryan "TheBS" Smith mailto:b.j.smith@... chat:thebs413
Engineer Absolute Value Systems, Inc. http://www.linux-wlan.org
President SmithConcepts, Inc. http://www.SmithConcepts.com