Searching \ for 'computer splitter box project' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: www.piclist.com/techref/index.htm?key=computer+splitter
Search entire site for: 'computer splitter box project'.

Truncated match.
PICList Thread
'computer splitter box project'
1999\07\30@070627 by marquis De

picon face
hello picsters,
i got an idea for a project!
and it is something im sure all of us could use...
because i know im not the only one with multiple computers. so here it
is:
computer keyboard splitter boxes come in two basic varietys:
1. you got youre basic two-way or sometimes you can find a four-way
box, with a rotary switch, and maybe a reset button if somebody was
thinking (cost: about $50)
2. you have the expensive digital ones, with anywhere from 8 to 20
ports, and they usually have special bulkheads you have to buy also.
(cost $200-400, plus bulkheads)
so i got to think the other night, my computers were all on, and my NT
server kept timing out on the key port, and then i have to hit the
reset switch on the box...then sometimes it works, frees up the mouse,
and i can work on several computers at once, but sometimes it doesnt
work though...the serial mouse, usually comes up, so then i can click
"shutdown" or "restart" and then whats the point?
so i got to looking at the digital boxes, and said those famous last
words when i saw the price tag $299?!?!? SHIT, I CAN BUILD IT FOR
LESS?!?!?!
so here i am, thinking of all the threads ive seen lately about rs-232
and the pic, or the parallel port and the pic...
so i think you all can see where im going with this...
i want to scrap that switch box, maybe use the connectors for this
project, and make a pic controlled switch box.
now the keyport, of every computer is always looking to see if the
keyboard is present, how im not certain, but im sure with a scope or
logic analyzer, i can find out.
but my theory is the 5 volt side, is sending a signal trying to get the
"ack" signal back, or maybe its simply being held high by a simple
ls74xx chip. the 12 volt is most likely just a power supply to the
processor in the keyboard. the mouse rather simple also, as it has only
three wires...
from there i think its simply a matter of mimicing the signals that are
sent to them, and sending a "ack" right back, as the port is idle
so that as a port has been "switched" to another output (another
computer) the computer thinks its still there. the video, i wont mess
with, as i have more monitors than i know what to do with, second of
all, as the one computer is thinking, and another is doing something
else...i can work on another till the video tells me that its done with
its task.
so, any ideas, advice, etc... let me know!
thanks desade
_____________________________________________________________
Do You Yahoo!?
Free instant messaging and more at http://messenger.yahoo.com

1999\07\30@095204 by Byron A Jeff

face picon face
-
-  hello picsters,
- i got an idea for a project!
- and it is something im sure all of us could use...
- because i know im not the only one with multiple computers. so here it
- is:
- computer keyboard splitter boxes come in two basic varietys:
-  1. you got youre basic two-way or sometimes you can find a four-way
- box, with a rotary switch, and maybe a reset button if somebody was
- thinking (cost: about $50)
-  2. you have the expensive digital ones, with anywhere from 8 to 20
- ports, and they usually have special bulkheads you have to buy also.
- (cost $200-400, plus bulkheads)
-  so i got to think the other night, my computers were all on, and my NT
- server kept timing out on the key port, and then i have to hit the
- reset switch on the box...then sometimes it works, frees up the mouse,
- and i can work on several computers at once, but sometimes it doesnt
- work though...the serial mouse, usually comes up, so then i can click
- "shutdown" or "restart" and then whats the point?
-  so i got to looking at the digital boxes, and said those famous last
- words when i saw the price tag $299?!?!? SHIT, I CAN BUILD IT FOR
- LESS?!?!?!

May be able to save you some work. Go take a look at BGMicro (http://www.bgmicro.com).
They have 4 port KB/mouse/video splitters in the $30 range.

BAJ

1999\07\30@103528 by eplus1

flavicon
face
Some of this may help:

Doctor Dobs Journal #286 on page 66 had an article on interfacing an 8 bit
microcontroller to the PC Keyboard

The keyboard scan codes you see listed in Books and FAQs and so forth are
NOT current for a MFII (101-key expanded) keyboard. The Linux source code
does document all this.

Typical data transfer speed from the keyboard is approx. 8kHz . The clock
pulses are 60 or 70 uS long so 120uS for the period.

see also:
Articles about XT and AT type keyboards can be found in April/May 1995
issues of Circuit Cellar Ink.

An early copy of Micro Cornucopia ( March-April 1990 ) has the details about
standards, interface chips etc

John Voth has keyboard interfacing information at:
http://nyquist.ee.ualberta.ca/~jdv/

http://www.enterprise.ca/~jbilous/kybrd03.htm

http://www.barcodeman.com/scan_doc.html

http://www.senet.com.au/~cpeacock     for details on how to interface an AT
keyboard to a system expecting ASCII     input.

http://boole.stanford.edu/~gdefouw/kbd/pic.html     (PIC 16C84 Keyboard
Transmit Routine)

http://ourworld.compuserve.com/homepages/steve_lawther/keybinfo.htm keyboard
to LCD display keyboard code viewer, with diagram etc.

http://www.repairfaq.org/filipg/LINK/PORTS/F_Keyboard_FAQ.html

http://members.tripod.com/~ilkerf/c64tower/F_Keyboard_FAQ.html is Yet
Another     Keyboard FAQ.

http://www.geocities.com/SiliconValley/Bay/8302/keybrd.htm

http://www.brouhaha.com/~eric/pic/

http://www.hth.com/filelibrary/TXTFILES/keyboard.txt

www-dept.cs.ucl.ac.uk/staff/B.Rosenberg/kbd/chord.html
Interesting Chord Keyboards summary:

http://www.atmel.com/atmel/acrobat/doc1235.pdf has C code for interfacing an
AVR processor to a keyboard.

http://www.hut.fi/Misc/Electronics/hwprojects.html#pc_keyboard, good PC
hardware projects

http://www.hagstromelectronics.com Hagstrom Electronics, 2 Green Lantern
Boulevard Endicott, New York 13760, 1-888-690-9080 9x9 and 12x12 matrix to
PC or RS232 encoder boards. I was pleased when I worked with them on a
10-key to PC keyboard interface.

http://www.usar.com/prodnser/keycod.htm

http://junitec.ist.utl.pt/einfo/hwprojects.html#pc_keyboard

http://www.freebsd.org/~fsmp/HomeAuto/Focus.html

http://www3.bc.sympatico.ca/kaarvik/kaarvik.htm Ken's Gameboy and PIC
Projects Page

James Newton, webmaster http://get.to/techref
spam_OUTjamesnewtonTakeThisOuTspamgeocities.com <.....jamesnewtonKILLspamspam@spam@geocities.com>
1-619-652-0593 phoneÊ



{Original Message removed}

1999\07\30@140119 by Adam Chapweske

flavicon
face
Yet another page on the AT keyboard can be found at
http://panda.cs.ndsu.nodak.edu/~achapwes/PICmicro/keyboard/keyboard.html


-Adam C.

{Quote hidden}

> {Original Message removed}

1999\07\30@141951 by Greg Wiley

picon face
Byron A Jeff <EraseMEbyronspam_OUTspamTakeThisOuTCC.GATECH.EDU> wrote:

> > computer keyboard splitter boxes come in two basic varietys:
> >  so i got to looking at the digital boxes, and said those famous last
> > words when i saw the price tag $299?!?!?

> May be able to save you some work. Go take a look at
> BGMicro (http://www.bgmicro.com).
> They have 4 port KB/mouse/video splitters in the $30 range.

My experience with the cheap multiplexors is that they
are completely passive.  They do not provide mouse
and keyboard emulation to deselected hosts, which leads
to frequent lock-ups.  I think a PIC-based active multi-
plexor is doable and the electronics inexpensive.  How-
ever, it's the packaging components that would be expen-
sive for single units.  When you add up the case, switches,
connectors, etc., that $299 looks pretty good.  If you
already have those parts from an existing passive box,
then you can probably save some money and, more
importantly, have some fun with it.

I have used lots of these.  Here are some of the cooler
features you might consider for your project.

1) Interconnect capabilities - so several units can be
stacked to form one larger unit.

2) Keyboard escapes  - allow operators to control the
switches without leaving their keyboards.

3) Scanning - selects hosts, one-by-one, for a fixed length
of time for monitoring.

4) I have seen (but not used myself) units that also
process the video signal and provide things like on-screen
interfaces and multi-host displays on a quartered screen.

Good luck and have fun.

 -greg


'computer splitter box project'
1999\08\02@151036 by Mark Willis
flavicon
face
One major problem I know of is that the keyboard having it's power
Glitch badly, each time you switch the switch on the cheapest units,
causes bad problems.  Including sometimes blowing the keyboard fuses (2A
microfuse) on the motherboard, which is a pain (& sometimes voids the
warranty if you repair it yourself.)

So, the very cheapest solution to these, is to just isolate the 5V
supply from the connected computers, and supply a nice 9V or so DC as
input to a 7805 (or similar) regulator inside the switchbox.  This can
be as cheap as $5, and make a large difference.

 Mark

marquis De wrote:
{Quote hidden}

More... (looser matching)
- Last day of these posts
- In 1999 , 2000 only
- Today
- New search...