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'[EE]: Faking out a laptop external keyboard port.'
2001\05\15@205658 by Craig Lee

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I am wanting to use a cute cat (sp) with my laptop computer,
but the only way it will work is to at least momentarily
connect a keyboard.

I would like to skip this step, has anybody looked into this
problem, or are familiar with this problem?

Craig

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2001\05\15@211341 by Bob Ammerman

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Hm.....

The Cue Cat Works with my Dell Inspiron without any external keyboard.

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)

{Original Message removed}

2001\05\15@212258 by Charles Craft

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Maybe this will help:

http://www.circuitcellar.com/TOC-frame.htm

From the Bench
Taking a Cue from a Cat-Hardware Cleanup with :CueCat-Jeff Bachiochi
Fact or fiction-nothing is free and the Internet is getting harder to
navigate. Jeff found a device that's freely distributed and can make
navigating the Internet as easy as scanning a bar code. pg.70

Keywords: :CueCat, bar code, scanner, :CRQ, PC, keyboard, serial, data,
16F84, MAX232


{Original Message removed}

2001\05\15@220856 by Craig Lee

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Nope.  Have to buy the mag to see if the information contained within
is anything more than the text you supplied.

{Original Message removed}

2001\05\15@221538 by Craig Lee

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I've tried it with my Toshiba Tecra and an IBM Thinkpad, and both need the
keyboard
momentarily connected to work.  Perhaps mine is 'de-clawed', but that
shouldn't effect
things.... or perhaps it has something to do with the tempermental 4066.
Your's may
have just the right amount of purr....



{Original Message removed}

2001\05\15@224106 by Bob Blick

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At 09:05 PM 5/15/2001 -0500, you wrote:
>Nope.  Have to buy the mag to see if the information contained within
>is anything more than the text you supplied.

No, the code is available, go to their ftp site.

Cheers,

Bob

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2001\05\16@085129 by Fisher, Tom L (FISHER)

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Unlike table-top computers, most laptops have only one port for EITHER an
external keyboard OR a mouse.  When the laptop notices something plugged
into the external port, it sends an interrogation to find out what kind of
device is there so it can interpret the incoming signal correctly.  I think
what's happening in your case is that you're having to wait until the
keyboard gives the correct reply before plugging in the :CueCat which is
probably incapable of replying.

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2001\05\16@091412 by Bob Ammerman

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And that explains why it works with my Dell Inspiron: This machine has _two_
PS2 ports (at least when docked) and I am guessing it doesn't have to figure
out what is attached to them.

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)

{Original Message removed}

2001\05\16@204802 by Craig Lee

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I wonder if I can get away with a pushbutton switch with a 10k resistor to
ground to fake out the I2C into thinking the device acknowledged.  Will try
this after supper.

Even hackers need to eat sometimes.

{Original Message removed}

2001\05\16@205431 by Alexandre Domingos F. Souza

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>I wonder if I can get away with a pushbutton switch with a 10k resistor to
>ground to fake out the I2C into thinking the device acknowledged.  Will try
>this after supper.

       PS/2 is different of I2c, eh?

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2001\05\16@234843 by Craig Lee

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Is it?

Eh?  I know your not Canadian.

Don't hear that any more now that I'm in USA..

Craig

-----Original Message-----
From: pic microcontroller discussion list
[EraseMEPICLISTspam_OUTspamTakeThisOuTMITVMA.MIT.EDU]On Behalf Of Alexandre Domingos F. Souza
Sent: Wednesday, May 16, 2001 7:58 PM
To: PICLISTspamspam_OUTMITVMA.MIT.EDU
Subject: Re: [EE]: Faking out a laptop external keyboard port.


>I wonder if I can get away with a pushbutton switch with a 10k resistor to
>ground to fake out the I2C into thinking the device acknowledged.  Will try
>this after supper.

       PS/2 is different of I2c, eh?

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2001\05\17@075309 by Olin Lathrop

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> I wonder if I can get away with a pushbutton switch with a 10k resistor to
> ground to fake out the I2C into thinking the device acknowledged.  Will
try
> this after supper.

Huh?  The message you were replying to was talking about PS2, not IIC.
Also, 10K to ground on an IIC SDA line is rather unlikely to produce the 0
level of an ACK, even if you could somehow press the pushbutton at the right
microsecond.


********************************************************************
Olin Lathrop, embedded systems consultant in Littleton Massachusetts
(978) 742-9014, RemoveMEolinTakeThisOuTspamembedinc.com, http://www.embedinc.com

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2001\05\17@203829 by Craig Lee

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If it IS just an Ack it's looking for, I don't see why it won't work.

DATA    X X X X X X X X _
CLK     ||||||||||||||||||

The host sends a 7 bit or 10 bit address followed by the R/W bit then
floats the data line waiting for the slave to acknowledge.

The current sourced or sunk by the host is sufficient to overdrive my
10k resistor at all times except for the time when the host go's hi-z
and starts listening to the bus instead of talking.

Think about it.  The theory is sound.  However, it is purely academic
(and those who know me, know how useless I find academia).  Until I
actually try it, it's BS.

Craig

{Original Message removed}

2001\05\17@205454 by Barry Gershenfeld

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>The current sourced or sunk by the host is sufficient to overdrive my
>10k resistor at all times except for the time when the host go's hi-z
>and starts listening to the bus instead of talking.

The problem is that line is never driven high by anybody.  A "1"
is supposed to be the result of everybody floating.  Because
of that there is already a resistor to + and it's usually
around 10k already.

Not everyone follows the spec, though.

Keyboards aren't I2C, unless I haven't heard (I'm always
being surprised)

In the old days keyboards were more like SPI and the protocol
was that they sent 0xAA upon being reset.

Barry

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2001\05\18@090750 by Olin Lathrop

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> The current sourced or sunk by the host is sufficient to overdrive my
> 10k resistor at all times except for the time when the host go's hi-z
> and starts listening to the bus instead of talking.
>
> Think about it.  The theory is sound.

I think you forgot that IIC is open collector and requires passive pullups
on both bus lines.  These tend to be significantly lower than 10K.  At best,
a 10K to ground will have no effect since the pullup overcomes it.  At
worst, the pullup doesn't overcome it and the bus line is permanently 0.


********************************************************************
Olin Lathrop, embedded systems consultant in Littleton Massachusetts
(978) 742-9014, spamBeGoneolinspamBeGonespamembedinc.com, http://www.embedinc.com

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2001\05\18@140829 by Peter L. Peres

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> Keyboards aren't I2C, unless I haven't heard (I'm always
> being surprised)

No, but they use the same kind of signalling (like multimaster I2C --
synchonous 8 bit or more 'words') using open drain drivers for both clock
and data at both ends and pullups somewhere in the middle. Wrt button: I'd
connect the button directly to GND and try. Larger miracles are known to
have happened. Perhaps add a 220R resistor in series with the button to
limit damage.

The last time I checked the protocol was not especially timing sensitive.
This is because the host cannot know how long the keyboard takes to
initialize. This is also the same 'feature' that makes some machines hang
on boot if they have a keyboard configured but none attached (and take
ages to do that).

One interesting thing to try is to make a breakout box and connect TWO
keyboards to the same machine. One should be connected at boot time and
the other a little later (perhaps controlled by a PIC). Then try to see if
one can type at each keyboard. There will be some issues with this when
switching modes, but it would be nice to know I think.

Peter

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2001\05\19@040851 by V sml

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> One interesting thing to try is to make a breakout box and connect TWO
> keyboards to the same machine. One should be connected at boot time and
> the other a little later (perhaps controlled by a PIC). Then try to see if
> one can type at each keyboard. There will be some issues with this when
> switching modes, but it would be nice to know I think.

It will work.  But only if one keyboard is allowed to reply to the PC.  The
PC does send down command to the keyboard like set number lock indicator,
set cap lock indictaor, etc.    And when this happens, the keyboard has to
reply with an "ACK" ($FA).  There simplest way is to manipulate the clock
line to multiplex the keyboard, even a simple polling of the clock line will
work very well because the keyboard has internal buffer to wait for the
clock line to be high to send out the key strobe.

But if you deal with an OS or an application does set the keyboard to
non-default codings, then it is a different story.

I am not sure what is the Cue thing.  Maybe playing with the BIOS settings
of keyboard might help.  Normally, you press the <del> during the PC boot up
to get there.  But be aware of what you are doing.

Mouse is a different matter, because the mouse is powered up as "disable"
until it is "enable" by the PC. And mouse send in 3-bytes packet, and miss a
byte you have a drunk mouse jumping all over the screen.

Cheers, Ling SM

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