How does the keyboard input get into the terminal? [closed] - keyboard

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Can someone describe the way how keyboard input gets on the Computer Screen?! What kind of software/hardware is involved?
my question is what happens roughly or exactly when i press a key on my keyboard? what kind of software hardware is involved. does the 8 bit ascii gets directly to the cpu? and how does it get onto the screen with the help of the OS e.g. Linux?

I recommend you check out this website called HowStuffWorks on How Computer Keyboards Work. It states in sum:
As you type, the processor in the keyboard analyzes the key matrix and
determines what characters to send to the computer. It maintains these
characters in its memory buffer and then sends the data.
and
Many keyboards connect to the computer through a cable with a PS/2 or
USB (Universal Serial Bus) connector. Laptops use internal connectors.
and finally
Whether it's through a cable or wireless, the signal from the keyboard
is monitored by the computer's keyboard controller. This is an
integrated circuit (IC) that processes all of the data that comes from
the keyboard and forwards it to the operating system. When the
operating system (OS) is notified that there is data from the
keyboard, it checks to see if the keyboard data is a system level
command. A good example of this is Ctrl-Alt-Delete on a Windows
computer, which reboots the system. Then, the OS passes the keyboard
data on to the current application.
The data is sent via cable or wireless also (IR or other wireless technology).
Wikipedia also has a nice writeup on keyboards,
Computer keyboards include control circuitry to convert key presses
into key codes that the computer's electronics can understand. The key
switches are connected via the printed circuit board in an electrical
X-Y matrix where a voltage is provided sequentially to the Y lines
and, when a key is depressed, detected sequentially by scanning the X
lines.

Related

where to store Serial number in an embedded system running fedora 11 [closed]

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Closed 10 years ago.
I have a task to accept serial number in Json format and validate it using C++ and store it and user is not allowed to change it. Only production team needs to change it. Now my question is where would I saved or stored the serial number . The product is an embedded system and run via complact flash card .
The product is embedded system run on Fedora system and it is not trial version. The user will buy the whole product and only production team are allowed to assign serial number to individual product. In case of software crash or upgration we dont want to loose serial number.
Thanks and regards,
Sam
I have no idea about the architecture of the system that you are using; its memory map, any protected flash resources that you have available.
When storing serial number type information I normally ensure the following:
The item to be stored is held in its own flash sector.
This sector is not visible to any normal flash erasure code
Before writing a value, the serial number sector must be blank (no serial number assigned to the unit before). Attempting to rewrite the data is rejected.
A CRC is added to the serial number data for validation.
All of the processors that I have used have a small amount of configuration or information flash that can be used for calibration values etc. I use some of this memory as a write once serial number store.
Assuming users are not able to access your system (or at least not as root), a simple file in /etc/ might do.
This also rather assumes you don't overwrite the entire flash when (if?) you upgrade the software.

Using a piano keyboard as a computer keyboard [closed]

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I have RSI problems and have tried 30 different computer keyboards which all caused me pain. Playing piano does not cause me pain. I have played piano for around 20 years without any pain issues. I would like to know if there is a way to capture MIDI from a MIDI keyboard and output keyboard strokes. I know nothing at all about MIDI but I would like some guidance on how to convert this signal into a keystroke.
I haven't done any MIDI programming in years, but your fundamental idea is very sound (no pun).
MIDI is a stream of "events" (or "messages"), two of the most fundamental being "note on" and "note off" which carry with them the note number (0 = C five octaves below middle C, through 127 = G five octaves above the G above middle C, in semi-tones). These events carry a "velocity" number on keyboards that are velocity sensitive ("touch sensitive"), with a force of (you guessed it) between 0 and 127.
Between velocity, chording, and the pedals, I'd think you could come up with quite a good "typing" interface for the piano keyboard. Chording in particular could be a very powerful technique — as I mentioned in the comments, it's why rank-and-file stenographers can use a stenotype machine to keep up with people talking for hours in a row, when even top-flight typists wouldn't be able to for any length of time via normal typewriter-style keyboards. As with machine stenography, you'd need a "dictionary" of the meanings of chords and sequences of chords. (Can you tell I used to work in the software side of machine stenography?)
To do this, the fundamental pieces are:
Receiving MIDI input. Don't try to do this yourself, use a library. Edit: Apparently, the Java Sound API supports MIDI, including receiving events from MIDI controllers. Cool. This page may also be useful.
Converting that data into the keystrokes you want to send, e.g. via the dictionary I mentioned above.
Outputting the keystrokes to the computer.
To be most broadly-compatible with software, you'd have to write this as a keyboard device driver. This is a plug-in to the operating system that serves as a source for keyboard events, talking to the underlying hardware (in your case, the piano keyboard). For Windows and Linux, you're probably going to want to use C for that.
However, since you're just generating keystrokes (not trying to intercept them, which I was trying to do years ago), you may be able to use whatever features the operating system has for sending artificial keystrokes. Windows has an interface for doing that (probably several, the one I'm thinking of is SendInput but I know there's some "journal" interface that does something similar), and I'm sure other operating systems do as well. That may well be sufficient for your purposes — it's where I'd start, because the device driver route is going to be awkward and you'd probably have to use a different language for it than Java. (I'm a big fan of Java, but the interfaces that operating systems use to talk to device drivers tend to be more easily consumed via C and similar.)
Update: More about the "dictionary" of chords to keystrokes:
Basically, the dictionary is a trie (thanks, #Adam) that we search with longest-prefix matching. Details:
In machine stenography, the stenographer writes by pressing multiple keys on the stenotype machine at the same time, then releasing them all. They call this a "stroke" of the keyboard; it's like playing a chord on the piano. Strokes frequently (but not always) correspond to a syllable of spoken language. Like syllables, sometimes one stroke (chord) has meaning all on its own, other times it only has meaning combined with following strokes. (Think "good" vs. "good" followed by "bye"). Although they'll be heavily influenced by the school at which they studied, each stenographer will have their own "dictionary" of what strokes they use to mean what, a dictionary they will continuously hone over the course of their working lives. The dictionary will have entries where the stenographic part ("steno", for short) is one stroke long, or multiple strokes long. Frequently, there will be several entries with the same starting stroke which are differentiated by their length and by the subsequent strokes. For instance (and I won't use real steno here, just placeholders), there may be these entries:
A = alpha
A/B = alphabet
A/B/C = alphabetic
A/C = air conditioning
B = bee
B/C = because
C = sea
D = dog
D/D = Dee Dee
(Those letters aren't meant to be musical notes, just abstract markers.)
Note that A starts multiple entries, and also note that how you translate a C stroke depends on whether you've previously seen an A, a B, or you're starting fresh.
Also note that (although not shown in the very small sample above), there may be multiple ways to "play" the same word or phrase, rather than just one. Stenographers do that to make it easier to flow from a preceding word to the next depending on hand position. There's an obvious analogy to music there, and you could use that to make your typing flow more akin to playing music, in order to both prevent this from negatively affecting your piano playing and to maximize the likelihood of this actually helping with the RSI.
When translating steno into standard text, again we use a "longest-prefix match" search: The translation algorithm starts with the first stroke ever written, and looks for entries starting with that stroke. If there is only one entry, and it's one stroke long, then we can reliably say "that's the entry to use", output the corresponding text, and then start fresh with the next stroke. But more likely, that stroke starts multiple entries of varying lengths. So we look at the next stroke and see if there are entries that start with those two strokes in order; and so on until we get a match.
So with the dictionary above, suppose we saw this sequence:
A C B B C A B C A B D
Here's how we'd translate it:
A is the start of three entries of varying lengths; look at next stroke: C
A/C matches only one entry; output "air conditioning" and start fresh with next stroke: B
B starts two entries; look at next stroke: B
B/B doesn't start anything; take the longest previous match (B) and output that ("bee")
Having output B = "bee", we still have a B stroke in our buffer. It starts two entries, so look at the next stroke: C
B/C matches one entry; output "because" and start fresh with the next stroke: A
A starts three entries; look at the next stroke: B
A/B starts two entries; look at the next stroke: C
A/B/C only matches one entry; output "alphabetic" and start fresh with the next stroke: A
A starts three entries; look at next stroke: B
A/B starts two entries; look at next stroke: D
A/B/D doesn't match anything, so take the longest previous match (A/B) and use it to output "alphabet". That leaves us with D still in the buffer.
D starts two entries, so we would normally look at the next stroke — but we've processed all the strokes, so consider it in isolation. In isolation, it translates as "dog" so output that.
Aspects of the above to note:
You have a buffer of strokes you've read but haven't translated yet.
You always want to match the most strokes against a single entry that you can. A/B should be translated as "alphabet", not "alpha" and "bee".
(Not shown above) You may well have sequences of strokes that you can't translate, because they don't match anything in the dictionary. (Steno people use the noun "untranslate" -- e.g., with our dictionary, the strokes E would be an "untranslate".)
(Not shown above) Some theories of steno allow the same set of strokes to mean more than one thing, based on a broader context. Steno people call these "conflicts". You probably want to disallow them in your project, and in fact when steno used to be translated manually by the stenographer, conflicts were fine because they'd know just by where in the sentence they were what the right choice was, but with the rise of machine translation, conflict-free theories of steno arose specifically to avoid having to go through the resulting translated text and "fix" conflicts.
Translating in real time (which you'd be doing) means that if you receive a partial match, you'll want to hold onto it while waiting for the next chord — but probably only up to a timeout, at which point you'd translate what you have in the buffer as best you can. (Or maybe you don't want a timeout; it's your call.)
Probably best to have a stroke that says "disregard the previous stroke"
Probably best to have a stroke that says "completely clear the buffer without outputting anything"
Consider doing something in hardware that emulates a usb (or ps/2?) keyboard. You will no longer be dependent on a specific OS, or specific OS API. A hardware solution will stand the test of time. Don't be stuck using an old API in Windows 7 when everyone else is running Windows 11! Arduino is pretty easy to learn.
Arduino MIDI hardware is available off of the shelf
Arduinos have been used to emulate keyboard devices
There is a ton of info and help out there for Arduino. It is a hardware hacking platform built for newbies. It will only get bigger now that Google is pushing Arduino.
EDIT: Virtual USB Keyboard software and hardware
It sounds to me like you're looking less for advice on how to build this yourself and more asking what resources are already out there to accomplish what you want. Depending on your OS, there are many ways to accomplish this without having to write your own program from scratch:
MIDI Stroke
Free. For Mac OS X 10.3 and up. This one specifically comes with "the ability to use any MIDI keyboard as a full blown computer keyboard replacement."
Bome's MIDI Translator
Free/Postcardware (it's a bit odd). For Windows 2000 and up, and Mac OS X. It initially appears to be more geared towards AutoHotkey-type usage, but on further looking I think it could do what you want nicely.
Max and aka.keyboard
Free. For Mac OS X. Not exactly a "ready out of the box" solution, but if you are comfortable with basic device configuration, it shouldn't be too bad.
You can access the hardware with source code samples in .NET in MIDI DotNet.
A complete working sample as sourcecode to create MIDI notes data stream is in VB 5/6-Tipp 0521: MIDI-Töne erzeugen (Visual Basic 6.0, somewhere is .NET version too)
A way to simulate keyboard strokes is in VB 5/6-Tipp 0155: Tastaturereignisse simulieren (Visual Basic 6.0, somewhere is .NET version too)
And recognize keystrokes is describedin Tipp-Upload: VB.NET 0266: Globaler KeyHook.
Then, just use a good working matrix for a piano player
On piano and when you're a good player, you can have 10 fingers on the keyboard and if the matrix is usable you can be much more quickly that any computer keyboard user I think. :-)
In that case, if I understand your question right, it should not be a big thing.
I studied piano performance in college and then got into interaction design, programming, and using Vim, so I have actually spent a lot of time prototyping things like this.
You can get this working pretty quick in Linux by using the graphical programming language for multimedia artists, "Pure Data," along with the x11key external by Alex Andre.
On Mac, you can use MidiStroke. I believe a method on Windows involved the MidiOx and AutoHotKey tools. At another time I had a version going using the Java plugin for Max/MSP. I believe Patrice Colet made a windows external for Pure Data that worked as well, but I can't seem to locate it anymore. Also, there's an external for MaxMSP that can do this on Windows. Finally, the non-free but awesome Osculator can do what you want - see the features page.
When I got it working, I never stuck with it, because I couldn't stop tooling with the layout. It was cool just having my monitor on my electric keyboard, though! Good luck.
About MIDI
You stated that you "know nothing at all about MIDI". MIDI technology is fairly straight-forward once you grasp it, but it can be confusing at the outset. One of the resources that has been tremendously helpful for me in understanding the foundations for MIDI (which are certainly necessary if you want to program MIDI interactions), is a book called MIDI for the Technophobe. It's an easy book to read and is very helpful.
Pure Data & Max
In my experience developing interactive multimedia, there are two very similar programs I have encountered that facilitate connecting and mapping signals/inputs from any device.
These are Max for a Mac environment and Pure Data for a PC environment. Both have a plethora of online documentation and YouTube tutorials. The video Max/MSP Tutorial 1 - using your computer keyboard as midikeyboard (ableton style) demonstrates a program built in Max that maps a computer keyboard to a MIDI keyboard's inputs (which is basically the exact opposite of what you are trying to do). You could get your intended results by using the same pattern, but reversing the signals/mappings.
AutoHotKey
AutoHotKey is a free open source utility for Windows that allows you to remap keys and buttons on your devices to macros. It natively supports QWERTY keyboards, joysticks and mouse macros.
However, I was able to find an implementation supporting the specific mapping you are looking for. These two threads explain the process:
MIDI IN support in AutoHotkey , the discussion of the use case. The author was looking for a program that could detect MIDI IN input and translate that to keypresses.
MIDI input library , the solution to the author's problem and the posted code/patch to AutoHotKey which actually implements your intended result.
Basically, it looks like AutoHotKey, along with this user's custom patch, will provide exactly what you need to create a mapping from a MIDI keyboard to a QWERTY keyboard's input signal. All you would have to do is install, configure and define your mappings.
Anything else?
Some of the other answers have given you much more extensive information on MIDI and MIDI programming, in general, but as your post states that doesn't seem to be quite what you are looking for. I would like to help you more if possible, but it would be easier if you could be more specific about the type of information you are looking for. For instance, are you more interested in how to convert a MIDI keyboard's input signals to a QWERTY keyboard's signals, or is your primary interest finding an out of the box solution to your specific problem? What are you looking for that has not yet been addressed?
You could hack your own USB keyboard pretty quickly using a Teenys micro controller.
In fact, they have example code for how to make a USB keyboard.
You could approach this two ways:
Get an old piano and wire up switches directly to the teensy
Add the additional logic to connect to the MIDI port and necessary decoding.
Actually, I worked on this a while ago, trying to capture Rock Band drum inputs into my computer (making a little Java homemade drum emulator) Anyway, I asked a question on here about that, Time delay problem (there is polling code in there, along with what I was attempting to do.). And if I can find my program I can give you the code, it uses a third-party API (JInput).
Good luck either way.
Try Bome's MIDI translator.
It works cross platform, can convert any MIDI input to a keystoke easily, quick to setup and configure, plus it's free for personal use.
There is a tutorial, Quick Tip: MIDI Translation – MIDI to Keystrokes, of how to easily set it up:
Basically, there are infinite possibilities of what you can do, including chording and modifier keys. I use it for my live audio rig to control my DAW using my piano and have never had an issue.
In Java, you can use JMF (Java Media framework) to convert MIDI signals.
Basic of keyboard design is easy to use, that is, the user interface; and place frequently used charcter/symbol handy.
The sample code and API in Java Sound Resources: Examples: Digital Signal Processing (DSP) help to understand how to process the signal.
Some more references:
Processing Audio with Controls
Digital Audio Signal Processing, 2nd Edition
A good library in .NET with full midi support (BASS), go to http://www.un4seen.com.
And for the other part, translating keyboard midi notes to keys and more, I would go for AutoItX, the ActiveX/COM and DLL interface to autoIt. Info and download, go to http://www.autoitscript.com/site/autoit/
No need to write keyboard driver.
There is a program called GlovePIE. You can program it in a simple scripting language, and I believe it supports MIDI. I'm not sure if this fits under the "Java" category, but still, it is a great program. I've used it to control robots using PS3 controllers. It's very powerful.
Many keyboards have a serial port (RS-232) connector to send MIDI signals to the computer. I use a program called Girder to convert serial port communication into keyboard strokes.
Girder has a "mapping" feature that lets you map each key, one by one, to the corresponding keystroke.
This might be the simple solution you're looking for!
Just learn stenography!
It's clear from all the discussion on your part. You don't want to re-invent any wheels, from a technical standpoint. But once you have a connection made (what this question is asking) and up and working, you still have most of the work ahead of you: You have to train your brain. You also have to invent the cleverest, most efficient way to do that - a design issue totally out of the rhealm of computer techies. You or any of us would fall short.
Fortunately, the problem has been solved and honed though centuries of maturing...
Learn stenography!
Yes, this will set you back some jack. But what are hundreds of hours of your own time worth, with at the end, a less favorable result? Besides, the stenography Wikipedia article says, 'it looks more like a piano keyboard'.
Unless, of course, you want to have a sideshow effect going. I would have to admit, I never thought of this possibility, it it would be really entertaining to see somebody bust out a text from a piano keyboard!
You could start with a USB keyboard with touchpad (or a pointing stick would be more ergonomic?), use Plover to translate it (I'm sure it can be configured to let the non-letter keys retain their functionality as they are critical for programming), or, follow the thread Re: Plover keyboard to roll your own USB stenography keyboard, or, buy a stenotype.
Good luck!
Take a look at MAME arcade gaming. They have built hardware devices to allow input from any number of different items. The iPac, for example, converts signals from input devices into USB that the computer can then use to emulate keys. You could use any combination of input devices arranged any way that seems comfortable with no crazy programming logic required--because the software to interpret input is already done and well tested.
I've seen flight simulator cockpit inputs, custom kiosks, and voting systems built in this method.....and the price is right!
To solve this you will need a few things:
A way to capture MIDI data from your keyboard. Depending upon the interface: MIDI interface (classic) or USB MIDI interface (modern) the most likely interface is to a computer as it provides the most options. USB host microcontrollers are not as simple as just using a computer.
A scheme to convert MIDI data into keystrokes. Like one user pointed out, chords are the way to go as the number of keys will not be dependent upon the number of piano keys.
A way to inject a key into the operating system. This will require a low-level driver to be accurate. I have played around with applications that inject keyboard and mouse data into applications in Windows 7, and it can be flaky and depend upon whether an application is currently in focus. This is hardest part of the interface. What may work is to create a HID USB keyboard microcontroller that also has a serial interface.
The serial interface would create a virtual serial port. The software that reads the MIDI data and produces the keystrokes could send a serial message to the virtual serial port. The microcontroller would send a keystroke so it would look like a standard keyboard input. This would allow interfacing both MIDI ports and USB MIDI keyboards.
Hmmm, with this type of interface you could also simulate a mouse and use some piano keys setup for the mouse axis and buttons. The pressure could be used to determine mouse pointer velocity. So you could eliminate the mouse as well. Another benefit of this approach is any type of input device you connect could talk to the virtual serial port to produce keyboard and mouse events. So if you wanted to add other hardware such as drum pedals or a joystick it would be a matter of adjusting the program that talks to the serial interface.
Another take on the above is like some posted above to use an Arduino, but also include USB Host Shield from Sparkfun to handle USB based music keyboards. This allows the Arduino to be programmed as a keyboard or keyboard mouse combo in the boot loader chip and allows the device to act a USB host for the USB based music keyboard. Then you are covered for both types. Although, I still think the virtual serial port method is more flexible and would be easier to program in the long run. The Arduino device will be harder to change than a desktop program or service.
There is another possibility:
Chorded one handed keyboards already exist. I have seen videos on them, but you would have to determine if those hurt your hands or not.
It should be fairly easy using something like the .NET DirectSound interface to hook into an MIDI device. You will need to identify your target MIDI device and then get the code to listen in on the incoming messages (there are articles about doing this via Google).
Since you are using the MIDI in as a keyboard there are basically only two MIDI messages that you need to detect, namely note on and note off. The MIDI message is three data bytes specifying the command, the note and the velocity. The note off is just the note number (sometimes 'bad' MIDI stacks send a note on with zero velocity which you also have to expect).
Once you have the messages translating them the keyboard output should be fairly simple from .NET.
There is plenty of advice in the other answers about the technicalities; I just wanted to give you an idea of the actual MIDI messages. Good luck!
You'll get better and happier results (regardless what operating system and/or DAW program you like to use) by playing any external MIDI keyboard as a controller through your sound card. Then route that into your GB software (or whatever) and tone generate the many sounds they have supplied you that way in real-time.
If your sound card does not support MIDI I/O's (ins / outs /thrus), that's not a problem. You can consider researching and investing in an external MIDI table top converter. Many are equipped to further convert MIDI outs to USB 2.0 (by- passing an existing sound card altogether).
For example: it's pretty tough getting "human like" grace note results via a Z and X change key option using a computer keyboard and pencil tool. When, instead, your own fingers can just play that with a MIDI keyboard from its own physical octave register ranges—immediately!
I realize budgetary constraints may be involved. But, some of these seemingly cheap "Casio" type 5 octave keyboards sold at Radio Shack for under $100.00 U.S. Dollars (*or less) is all you would need (plus, some of their on-board sound patches and sequencer modules sound and handle amazingly well for other things too).
RadioShack MIDI keyboard options.
As for external MIDI converters for existing sound cards, I've run some Google searches for you as follows with Mac platforms specifically in mind:
A lot of this external MIDI conversion information may be cumbersome to you at first, so I've broken down things more as "user friendly" for your considerations & budget:
MIDI sound cards
There's nothing wrong with facilitating virtual keyboards as VST's when using DAW. They have their place.
But, you sound like an accomplished keyboardist. So, why not consider the external MIDI conversion / keyboard options I just mentioned for yourself?
Good luck and I hope this gave you some ideas that can and will work for you!
If you don't want to do any programming yourself but just want the problem solved you can just buy a USB-MIDI-keyboard where you can re-assign any key to send a QWERTY keyboard output signal instead of a MIDI-output, for example M-Audio Axiom Pro
This method will work with any OS and any computer that supports standard USB-keyboards since the MIDI-keyboard will identify itself as a standard QWERTY keyboard.
You can use a simple AutoIt script to both read MIDI events, see MIDI Input.
You'll also need MIDI UDF and simulate key presses.
Reading MIDI events should be easy, but different MIDI controllers (instruments) have different features. Try to find out what your MIDI piano can do first, then see how you can best map those features to simulated QWERTY-keyboard presses.
If you want, you could have something on screen or in the tray to help you see what you are doing (that is, for Shift, Ctrl and Alt simulation).
You might take a look at chorded keyboards. They have the advantage that you don't need to write a driver for them before you can use them, and some are similar to the layout of a piano keyboard.
If you know coding in Java, you could use this way:
First, implement a javax.sound.midi.Receiver with a send(..) method that is mapping the 'Note on' events to keystrokes like you want.
You would need to get the MidiMessage's content with its getMessage method and intepret it in your fashion. The meaning of the message bytes can be found in MIDI Messages.
After receiving a 'note on' or 'note off' for a certain keyboard key, you may map that to a key you like by assigning it a constant of the KeyEvent class, something like C#4 -> KeyEvent.VK_A and so on. This key code can then be used by java.awt.Robot's keyPress and keyRelease methods to actually send the keystroke to the OS and thus to other applications.
I agree with Brian O'Dell's answer - if this were my project, I'd do it in hardware. It has the advantage of being platform and hardware independent - your box replaces the need for a MIDI-USB interface and a PC API.
mbed is a fast-prototyping platform that is very easy to learn, and has multiple advantages over Arduino IMHO (online compiler, 512 KB flash, 96 MHz, C++ language). It has a USB keyboard interface and a USB Midi interface pre-written for you.
The community is very friendly and willing to help, and there are a lot of existing projects using both MIDI and USB hid emulation - search Youtube for "mbed MIDI" or similar.
If you use Linux have a take at Footware.
It should be exactly what you're looking for - if you adjust the MIDI pitches to a keymapping of your liking...
I never thought this could be useful for anyone but me ;o)
Try using a microcontroller-based system, like Arduino.
This wouldn't be too tough.
I'm assuming you're on Windows, not sure about that though. I've written a MIDI sequencer, http://pianocheetah.com, in plain old C++, and it lets you use the piano keyboard to run commands. There isn't any reason you couldn't do the same thing to push keys
into the keyboard input stream.
But come on now. You remember how long it took you to learn
the keyboard in the first place, right?
Are you willing to go through that again?
And are you willing to pollute your blessed keyboard with
a bunch of stupid looking key symbols all over it?
You'll need to use at least 26 alpha, 10 numeric, 11 punctuation,
and at least 12 function keys AND their shifted states.
So that's 60 keys plus shifted states.
That'll burn up a full 5 octaves of keys.
You will be doing piano "hops" =all= the time.
Say goodbye to touch typing.
You may save yourself from RSI, but you've created another
different type of nightmare for yourself.
And good luck getting your boss to buy you a MIDI keyboard at work.
If you've learned to truly play piano, you've learned
how to play stress free. Do that on the QWERTY keyboard.
No tension. Start slow.

USB interface barcode scanners

Not exactly a programming question, but close. I'll try my luck anyway.
The keyboard wedge
barcode scanner inserts the
translation device between the reader
and the keyboard. Data sent through a
wedge appears as if it was typed into
the computer, while the keyboard
itself remains fully functional.
Because a computer using a keyboard
wedge can't tell the difference
between data that is entered by a
scanning device, or data that is
entered by keyboard typing, a wedge
can be used to easily add barcode
reading capability to an existing
computer without modifying software
applications.
I'd like to know if all USB interface barcode scanners automatically translate digital signals from a barcode reader into keyboard strokes for a applications just like wedge or is USB different from wedge?
Many thanks
There are all sorts of API to access barcode scanners -- by no means do they all work by making believe they're "the keyboard"!-) For example, here you can find a reasonable summary of possibilities (the classic rs232 approach, the "wedge" one, and USB-interface ones) albeit for a single firm producing them. Depending on what programming you're willing and able to do, your best choice might be any of these approaches, or others yet.

Program for HID USB Scale [closed]

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I'm looking for a program that can read the weight on a USB scale, namely the Pelouze 10lb USB Portable Scale. I thought it would have a virtual COM port driver but instead, it uses HID drivers. I've been searching for a whole month for a program that can help me transfer the reading of the scale to Microsoft Excel. Can someone help me out or point me in the right direction? I am absolutely illiterate to programming. Much gratitude any help given.
I can offer some helpful links.
The scales use the "HID point of sale" USB spec, a link to which can be found in the comments section of the blog post I mention below. I'd link direct, but the spam prevention mechanism prevents me.
There's a blog post on addressing the 25lb version of the scale from C#, here: http://nicholas.piasecki.name/blog/2008/11/reading-a-stamps-com-usb-scale-from-c-sharp/
The comments on that post are helpful - that's where you find the USB spec, there's also a comment showing how to get at the data without using the full HID library.
Good luck with your project!
I wrote some code to read from a Dymo USB scale using Python. It requires libusb and PyUSB.
This code is pretty general; it should work with any HID device that has just one configuration:
import usb.core
import usb.util
VENDOR_ID = 0x0922
PRODUCT_ID = 0x8003
# find the USB device
device = usb.core.find(idVendor=VENDOR_ID,
idProduct=PRODUCT_ID)
# use the first/default configuration
device.set_configuration()
# first endpoint
endpoint = device[0][(0,0)][0]
# read a data packet
attempts = 10
data = None
while data is None and attempts > 0:
try:
data = device.read(endpoint.bEndpointAddress,
endpoint.wMaxPacketSize)
except usb.core.USBError as e:
data = None
if e.args == ('Operation timed out',):
attempts -= 1
continue
print data
For the DYMO M10 scale I'm using, the data packet is a 6-element array like this array('B', [3, 2, 11, 255, 0, 0]).
The last two elements are used to calculate the weight.
In kg mode grams = data[4] + (256 * data[5]), and in pounds/ounces mode ounces = 0.1 * (data[4] + (256 * data[5])).
More info on my blog post.
The first question that you will need to answer is the exact HID use. USB describes a wide family of related protocols. USB HID is a subset, but this still covers a large array of devices. The HID specs defines a 32 bits "usage" identifier supporting up to 4 billion different types of HID devices, although only a fraction of those values have been assigned so far.
The Windows API you'll probably need is Raw Input. Unfortunately, this is not an interface for the programming illiterate.
For USB devices not supported directly by the O/S, you either need to be a programmer, or you need a program supplied by the device vendor. In this case, as it sounds like you're not a programmer, you should contact the manufacturer to see if they can provide any diagnostic or testware programs that could be used to read and capture the scale data. If you're lucky, such a program can be "batched" and it's output redirected, or something like that. Good luck.
Elane sells a line of USB HID scales and also has a Windows program to read the weight. Unfortunately, because of Stamps.com, that program is no longer free. At $15.50, it's not necessarily something I'd want to blindly try, but here it is:
http://www.elane.net/index.php?go=USB_pcsoftware
if you want to play detective this guy's advice might help :
http://nicholas.piasecki.name/blog/2008/11/reading-a-stamps-com-usb-scale-from-c-sharp/
Just ordered a DYMO scale myself so will post findings
http://r.lagserv.net/scalereader.htm
This is great code to get started with for C# and a Dymo scale using HidLibrary.
Just change the vendor ID to match that of your scale.
You can be up and running in a few minutes.
I used it with a Dymo S400.
I wrote my nodejs version and shared the code at https://github.com/PhantomRay/dymo-scale-nodejs.
It is only tested in Windows 10. Also, it has a simple web socket server mode built to it so that any web page can connect to it to read data.
I would assume that output from a USB HID device like this should appear to the USB host exactly as if the input was typed on a keyboard, i.e. on the scale stabilising, the weight would be sent over USB. This is the way most USB barcode scanners work.
If this is the case then the scale should just fire across the weight and it would appear in whatever application was active; Excel if that is where you wanted the input to end up.
However, I've looked over the specs and manual for the scale you specify and, unless I'm looking at the wrong model, although it is powered by USB I don't see any mention of the fact that it also communicates over USB. Do you have a URL or part number?

What's the *best* wireless keyboard / mouse set for programmers? [closed]

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Closed 9 years ago.
I've considered the following:
Logitech Desktop MX 5500
Microsoft Wireless Entertainment Desktop 8000
But I'd like see what other programmers would recommend.
I know you're looking for a set, but these two topics might be of interest:
https://stackoverflow.com/questions/687/keyboard-for-programmers
https://stackoverflow.com/questions/53132/mouse-for-programmer
Personally, I prefer to buy my stuff separately so I can find the best of both. For example, I'm currently using an Apple Keyboard and a Logitech MX Revolution mouse and I've been very impressed with both.
Being a 60 wpm typist on average, I can assure you that a wireless keyboard will only cause you frustration in the long run. It's gotten to the point where I actually swapped back in a wired keyboard because I have yet to find a wireless keyboard that can keep up with me.
Maybe it is because I have always loved the happy hacker keyboard, but I really like the very compact Apple's Bluetooth Keyboard (which does work with windows). But I really dig it's sleak design, and standard(ish) layout. The layout which matches my laptop, so that I can continue to touch type backslashes. for a mouse I am admitaditly less picky, and use either a mighty mouse or a Logitech V270 Bluetooth Travel Mouse.
I've used several, and the most durable bulletproof so far has been my Dell bluetooth pair. It's the same physical setup as the industrial-grade connected units. The bluetooth transmitter has been compatible for other devices as well. Good battery life, two AA's for the mouse and 3 AAA's for the keyboard - at least 6 weeks for a set of NiMH's.
I throw them in my backpack and take an extra bluetooth transmitter and they invariably work on clients' computers.
(source: dell.com)
All the logitechs, microsofts, and probably a half-dozen other off-brands haven't compared.
I use KeyTweak for the Ctl/CapsLock swap - actually I don't swap them - I have no use for a Caps Lock key.
I would avoid the Logitech MX5000/MX5500. If you can get something that is not Bluetooth, that would be best. The Bluetooth stack that Logitech uses is buggy. The keys like to get "stuck" which means they will act like they are pressed even when you release. That is especially bad if the key that gets stuck is backspace or delete. I've never had problems with their non-Bluetooth stuff.
Not a recommendation, as such, but a bit of guidance: many (but not all) wireless keyboards and mice "swallow" the first keystroke or split second of movement when you activate them after being idle. It's almost as though they go to sleep or something.
I've seen this with both Logitech and Microsoft wireless kit, as well as a third (relatively unknown) brand.
Your usage style might not be affected - but the missed mouse clicks and keystrokes drive me bonkers whenever I'm using a colleagues PC. Pause for thought, deside what to do next and then lose my train of thought when the machine doesn't respond. Arrrggh!
My advice: Whatever kit you settle upon, make sure you have the chance to try it out properly - in person - before committing your hard earned cash
I don't think there is a "best" here. I think you have to scope out components that feel right to you, perform well, and are in your price range.

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