Slashdot Mirror
Dongles to Fake Presence of a Keyboard?
An anonymous reader asks: "I have a Compaq IPAQ desktop system (legacy free) that will not boot headless. (Yes I did try to tell the BIOS to not generate a no keyboard error, but there is no such setting for the BIOS of this system.) Since I would like to use it such and don't wish to waste a keyboard just to keep it from complaining, I'd like to come up with a small dongle that would fake the system into thinking that there is a keyboard attached. This is the same basic thing that KVM's do, so the circuit shouldn't be that difficult to find. Has anyone heard of such a thing? Can anyone provide or point to somewhere where I can find the basic circuit for this?"
How hard would it be to take the connector part from a old non-working keyboard and wiring something like this up?
(link in Danish. Product #2.
Keyboard Emulator @ Froogle
In the U.S. I've seen new keyboards for as little as $10.00 (I think I've seen them for $5.00, but that might have been for a cheap mouse.)
I checked online (imagine that -- using Google instead of "Ask Slashdot"), and found this link to PCParts Leader for a list of keyboards, including a THREE DOLLAR keyboard. Even after paying shipping, you're still paying almost nothing.
Do you really think, by the time you pay for the PS2 connector (assuming it's that recent, or the older connector if it isn't), and any pieces that you'll spend less than $5-$10?
If you can't afford an el-cheapo keyboard, then how are you going to buy the connector and whatever else you need?
Sheesh. An "Ask Slashdot" to replace a $3 item with something else so you don't waste that $3 item? Now I see why so many people think it's become "Ask Slashgoogle."
We had the misfortune of buying about 20 similar systems (they have PS/2 ports) that are workstation class motherboards in rackmount cases and they will not boot without a keyboard attached. Since all we want is serial console access to them (we rarely even visit the site where they're installed) we don't want to waste a couple of KVMs hooking them up nor the rack space and clutter for keyboards. Seriously, we just need a simple loopback dongle.
I have run into the no-keyboard-present error when trying to convert an old desktop machine into a headless file server.
A bios upgrade gave me the ability to ignore the keyboard error.
Perhaps you should investigate that first.
Way 1:
Get a working receiver for a cordless keyboard. You do not need the actual keyboard, or a mouse. It also does not matter wheater it works with infrared or radio. Plug it into the computer. Finished. (If you are paranoid, you wrap a radio receiver into grounded tin foil to build a faraday cage, thus eleminating all incoming transmissions from wireless keyboards around. For infrared, some layers of duct tape across the infrared receiver should be sufficient, but tin foil will also do the job.)
Way 2:
Get a really, really, really cheep, but working keyboard (at least one key should work as expected). Open the case. Use brute force if needed. You should find a small printed circuit board (PCB) with one chip and three (or more) LEDs, it should be connected to a keyboard matrix made mostly of transparent foil. Rip off the keyboard matrix, throw away everything except the PCB and the keyboard cable. Place the PCB in a small case, or wrap it into duct tape. Connect the keyboard cable to the computer. Finished.
(Note: If you are really out of luck, the entire keyboard IS a PCB, or even worse, the entire keyboard is made of plastic foil, including the part carrying the chip and LEDs. In this case, getting another keyboard is the easiest way.)
Tux2000
Denken hilft.
Let me expand on this -- since I've investigated keyboards for a related project.
If you take apart a keyboard, there is usually a small circuitboard/chip in the upper right/middle of the keyboard, near where the cable comes in. This is the keyboard encoder. Its roughly, oh, say about 2"x1".
The rest of the keyboard is the casing and a few plastic membranes with traces for the keys. The keys on a keyboard form a matrix or grid, with, say, 13 inputs on each side. The top of the grid may be inputs A-M, and the side of the grid may be inputs 1-13. When a key is pressed, the two membranes meet at a junction of the grid, bridging the inputs. So pressing the 'b' key might bridge F-2, pressinig 'o' might bridge A-12. Rather nifty.
The encoder transates the grid junctions (A-12, F2, whatever) into key codes for the computer. When no keys are pressed, there are no grid junctions (ergo, none of the inputs are bridged/closed)
Therefore, to make a home-made dongle, take apart the keyboard, throw away the plastic membranes and casing, and put the circuit-board and most of the cord in a project-box from radioshack. Ergo, one keyboard dongle, no soldering.
If you are feeling adventurous, cut the cable down to 2" or so and resolder the keyboard.
If you have more money then time, why not google for "keyboard encoder". The KE18 model is $45 dollars, and is about 3"x2".
There's no two wires you can just connect on a ps2 plug to create a "loopback" that would work. The ps2 protocol is a two way protocol that involves the transfer of data back and forth. It doesn't simply detect a keyboard by seeing if a circuit is completed; in fact, the computer doesn't even generate the clock for the ps2 device. They keyboard itself is generating the clock.
Here is my recommendation if you are sending the keyboard to be colo'd or something. Do what I do. Take apart a real keyboard, dremel a small hole in the back of the case, use packing tape to tape the small chip inside a real(new) keyboard inside the case and run the ps2 cable outside to plug into the ps2 port.
Read more about the ps2 protocol here.
Chris Benard
Look for the cheapest keyboard around or use one with malfunctioning keys and strip the controller board, toss away the keys and voila!
Just a little cable hanging in the back of the pc.
NEOCA - Custom LED Flashlights
There is a bios patch called no_f1 that compaq put out for some of their systems to allow for headless operation, I've used it on some of my older machines. google it and good luck!