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Datahand Keyboard Resurrection

Discussion in 'Sensors and Actuators' started by mikeincousa, Apr 4, 2019.

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  1. mikeincousa

    mikeincousa

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    Sep 5, 2016
    I purchased a Datahand keyboard ca 1999. With a rebuild maybe seven years ago it served me well. I purchase it as a prosthetic device. It helped me greatly with coordination and composition. I achieved a high level of words per minute with very high accuracy.

    Datahand suddenly went out of business some time after that. I am more or less a disaster with a standard QUERTY keyboard. The oversized ones help some but I do not come close to what I could achieve on the Datahand. I put a link at the bottom that will give the background. There multiple images in Googlel

    A little over a year ago the left thumb switch quit working properly. Then I thought it a problem with the IR relay. That key is the most used one and it could have simply worn out. I can get it to toggle one way once but it gets stuck somehow. I can manually reset and but I can only do it once again. It is has been over a year since I tired to use it so I am a bit rusty on the details.

    I later thought there could be something wrong with one of the IC's further into the circuit? I am sure they are primitive given today's technology. But I would think the device does not need the latest and greatest to function like new with a repair of some sorts?

    Along the way I have thought that replacing the relay or installing a TTL gate could fix the problem?

    I have not engaged in any serious bread-boarding for several decades. A few years ago I purchased an Arduino Uno but did not get past the basics. I thought that if push comes to shove the Uno or a device like it could bypass the stall.

    I had reason to think about extracting firmware a few months ago and that got to again think about resurrecting the Datahand.

    I need a lot of guidance and direction on this so I will appreciate any thoughts or experiences you might kindly provide. I have a lot of very technical / legal writing ahead of me. It would be very helpful to do that with the Datahand.

    Thanks for any thought or suggestions.

    https://en.wikipedia.org/wiki/DataHand
     
  2. wejn

    wejn

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    Apr 4, 2019
    If you search for “lalboard” and “Jesusfreke” in your favorite search engine, you will find an opensource datahand clone.

    All you need is a 3D printer and some soldering skills.
     
  3. mikeincousa

    mikeincousa

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    Sep 5, 2016
    I am looking for a repair,not a replacement. This is major project beyond my skills and interests and time availability.
     
  4. JesusFreke

    JesusFreke

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    1
    Nov 28, 2020
    Apologies for resurrecting a dead thread, I just randomly ran across this :) No idea if you still need help, but I'm the lalboard guy wejn mentioned -- but I'm also quite familiar with datahand internals and could probably help diagnose/fix the issue.
     
    Martaine2005 likes this.
  5. mikeincousa

    mikeincousa

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    Sep 5, 2016
    What a nice surprise! Not hearing anything I had given up on the post. Thank you for making the connection.

    Talking off the top of my head the critical failure is that one of the thumb keys (left I think) is not engaging properly.

    As I recall I can get it to toggle once from a start-state but then it goes dead. What do you suggest that I do?

    Thanks for any thoughts.
     
  6. JesusFreke

    JesusFreke

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    Nov 28, 2020
    Is it the "shift/capslock" key that you press in a downward direction? And if so, is it the first detent for shift, or the full press for capslock that is the problem?

    Does it work again (once?) after replugging the keyboard?
     
  7. mikeincousa

    mikeincousa

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    Sep 5, 2016
    I have the DataHand out of storage.
    I have to admit that I am quite rusty with it. I went over the manuals and that quick review brought back some of the operations.

    Just completed a quick first run.

    It powers up.

    The only functionality I have found so far is the toggle between the NAS mode and Mouse mode.
    I did not get any keys to work in this mode, but I am recalling that some other operation is needed besides the toggle?

    The connecting cable is tight. I have a series of adapters for creating the cabling into my USB hub. All the supplied connects are PS/2 predating the USB era. I am thinking that maybe I will need to purchase a more direct patch cord? In contract if they were impaired some how I would not be able to mover the cursor?

    All the lefthand keys seem totally dead save for moving the cursor with the paddles, likely in the mouse mode?

    My next step will be opening up the right and left cases and blowing them out well.

    Maybe you have some thoughts on this first stall at this point?

    I will add to this reply after I compete the internal cleaning.

    I am recalling that when I put it away the problem was with what the manuals and training show as the "N" key. (Left thumb up). I may be wrong on that though?

    So far have not been able to find any mention of the functionality of that key in the manuals.

    I need to quit this for now and may not be able to get back to it until the middle of the coming week.

    I use Skype and Google Talk: if you feel a need to talk in real-time I will pass back my access numbers. BTW I am at UTC-7.
     
  8. mikeincousa

    mikeincousa

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    Sep 5, 2016
    I had forgot your instruction so I powered-up again.

    The Normal (green) light came on. I was able to do a limited amount of typing with either hand. Somehow in typing I did something that brought up the NAS light. I could not toggle back to Normal. Not sure what I did and do not have the focus to sort it out any further right now.

    When I rebooted the keyboard the Normal light reappeared: I could type letters again with either hand. I did this a couple of times with the same results.

    I think this is what you were looking for?
     
  9. JesusFreke

    JesusFreke

    3
    1
    Nov 28, 2020
    It sounds like at a minimum, there is probably an issue with the left-hand "up" key (the N key you mentioned - "N" for "Normal"). That's the key that switches back to normal mode.

    I think the first thing to try would be to take it apart and unplug/replug and just generally "jiggle" the cable connecting the thumb cluster to the main board in the back of the left hand unit. Loose wire connections were a fairly common problem with my datahand at least.

    If that doesn't work, there are a few places that might be the problem. The only problem I can think of offhand that would cause *only* that single button to stop working would be if the LED or phototransistor for that key stopped working.

    To check if the LED itself is working, you should be able to see the IR from the LED with your phone's camera. There's an LED and phototransistor on either side of the base of that key. The LED will be the one that's nearest to you, when the keyboard is in a normal typing position. You'll need to peek in at the LED from the back side, since the LED is shining towards the back. You'll need to be in dim light, and the IR will show up as a purple glow.

    lit.jpg dim.jpg

    The only way I can think to diagnose a phototransistor failure would be to check it with a scope, or maybe a multimeter. I'm not sure if the duty cycle would be high enough to get much averaged voltage with a multimeter.

    Other than that, there are 3 ICs on the main board for that hand that could fail. A buffer for driving the LEDs, a multiplexer for scanning through the keys, and a schmitt trigger for debouncing the keys. Any problems with those components would almost certainly cause problems with multiple keys. So it's probably worth checking each key, and see if that normal mode key is the only one that doesn't work, or if there are any others. In particular, looking at my notes, the other key in the same scanning matrix "row" is the return key for that thumb.

    But yeah, the datahand never had proper USB functionality. They just included a ps/2 to usb adapter.
     
  10. mikeincousa

    mikeincousa

    8
    0
    Sep 5, 2016
    Thank you so much for all your sage comments. I will start working through them late this week.

    Looking for a loose/ cracked wire is certainly like the first place to start, following the classic axiom the device has to be plugged in to work!

    I do not own an oscilloscope right now but I know there are on-line apps that function like one.

    I have been considering trying those or purchasing a simple used one for an Arduino project. Maybe you would have an interest in it?

    The essence of the project is inflating and deflating a Blood Pressure cuff and data logging the points for unfiltered/ massaged file for graphing and calculations. The commercial units do not provide such data. Instead they engage multiple smoothing routines that, to me, obfuscate critical data and trends,

    Thanks again for your insights and guidance. I will report back when I have made some progress...
     
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