A keyset or chorded keyboard also called a chorded keyset, chord keyboard or chording keyboard is a computer input device that allows the user to enter characters or commands formed by pressing several keys together, like playing a " chord " on a piano. The large number of combinations available from a small number of keys allows text or commands to be entered with one hand, leaving the other hand free. A secondary advantage is that it can be built into a device such as a pocket-sized computer or a bicycle handlebar that is too small to contain a normal-sized keyboard. A chorded keyboard minus the board, typically designed to be used while held in the hand, is called a keyer. Douglas Engelbart introduced the chorded keyset as a computer interface in at what is often called " The Mother of All Demos ".
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A no-compromise, mechanical switch, 6-button chording keyboard, placed on the rear side of a tablet or a mobile phone. Not a member? You should Sign Up. Already have an account? Log In. To make the experience fit your profile, pick a username and tell us what interests you.
We found and based on your interests. Choose more interests. The desired functionality, however, is to be able to write reasonably long and complex texts, such as technical notes from meetings.
I have seen a number of implementations, such as this. The major problem is that Android relies heavily on finger gestures, and the mouse is not exceptionally useful; yet another is that both hands are occupied.
Finally, one-handed chorders are good for typing, but I personally find them difficult for navigation of course, your thumb may do arrows, but The current choice is to integrate. Currently I am undecided. On one hand, Arduino uses mA of power -- the phone screen consumes way more. On the other hand, since the phone has an extra compartment on the back, why not to add a battery? Hey, the keyboard may even charge the phone! Something to be evaluated in the prototypes.
If the former, a separate keyboard battery is a must, and both devices will drain the juice slightly faster. Let it be wired for now.
The plan is to source several different types and evaluate. Standard Tesselated Geometry - View all 8 components. The buttons have inverted force profile: the initial force is 35 gram, then decreases down to 11 gf hold force. The full key travel is 2. Buttons work with a pleasant metal click; at this point no intention to make it quiet let people admire a mechanical keyboard on the smartphone! The keyboard top now looks like this:. My PCBs from Allpcb.
The pin is pulled up by 10K resistor. To test a certain button, Arduino momentarily pulls up the control wire of corresponding LED, waits for 1 ms, then reads voltage on the pin If the switch is "not closed" that is no chopper between the LED and the photo-transistor pin 15 will be low.
If the switch is "closed", wire will be high. After switching the LED off, Arduiono further waits 1 ms, so the photo-transistor can lock completely, after that, the next button is tested, and so on. I fixed this by soldering the 5V wire to the board and cutting the trace to Arduino pin. The second prototype requires only one-sided board. Tracing is done in KiCAD. Based on the evaluation from of the first prototype, the 12 mm dome switches have been scrapped. The second prototype is based around the 6x6 dome switches, which are much lighter than the 12x12 -- only between 15 and 18 gram force is required for closure.
Above the switches, a hinged button is installed. I also finalized the cradle horizontal dimensions and the placement of the thumb Shifters. For faster prototyping, there is no PCB and a lot of wires and hot glue in this version. The switches are covered with hinged caps. Finally, my second working prototype looked like this. And yes, the draft of this text was typed into the phone! Upright view. The case is made of two half-shells, two handles, and six buttons, all printed for now with PLA.
Printer step is 0. Note that I messed the charging port hole slightly and had to do a quick fix with molten filament. Two holes in the bottom are for the buttons' hinges.
Top of the cradle has a separate switch for the keyboard. The phone can be charged while in the cradle. If the charger is inserted, the keyboard is always on, independent of the switch. The buttons provide sufficient tactile feedback, so quick notes can be typed without constantly looking at the screen. Or even without looking at all.
Of course, there are typos, but try this trick on an on-screen keyboard. The prototype dimensions are x80x24 mm including the handles. The cradle is 46 mm longer, 5 mm wider and 14 mm thicker than the selected phone. The initial testing indicates the length of is comfortable for prolonged typing, and the user's hands don't overlap the screen. By using a PCB in the next prototype, the overall cradle thickness should be reduced to 18 mm, making it only 8 mm thicker than the phone.
As expected, the cheap 6x6 dome switches feel The mechanical key caps are far better than silicone pads try typing on a TV remote! For now, I will "type the prototype" and wait on the photo-interrupters from Aliexpress.
Yes, the next version will have an optical keyboard! The purpose of this was to check the software with real buttons and simultaneously evaluate the 12x12 mm tactile switches. A quick 3D print was made to hold the switches in the wanted positions:. The phone was held by two rubber bands. The schematics is as following:. The mouse can be added later if I decide on an Raspberry Pi build. This mode is activated by the left Shifter press and indicated by the left LED.
This mode is activated by the left Shifter double press and deactivated by the left Shifter. Left LED is lit Probably will make it blink in the future. This mode is activated by the right Shifter press. Right LED is lit. This mode is activated by the double right Shifter press. Both LEDs are lit. To cancel the mode back to 0, press any Shifter.
Additionally, the keyboard handles Russian alphabet, simulating the de-facto standard JCUKEN layout, so Android does not need to deal with any special phonetic keyboards. Arduino remembers if the current national layout has been activated and if the user moves to the "number" mode switches back to English. After the number mode is deactivated, the national symbol mode is automatically restored. It prevents the telephone on-screen keyboard popping up if one switches between input fields.
The whole sketch is in the project files. If somebody is interested, I can make an English-only version. View all 6 project logs. Create an account to leave a comment. Eduardo Zola. Christoph Tack.
Anthony DiGirolamo. Mattia Dal Ben. Become a member to follow this project and never miss any updates. About Us Contact Hackaday. By using our website and services, you expressly agree to the placement of our performance, functionality, and advertising cookies. Learn More. Yes, delete it Cancel. Hack a Day Menu Projects.
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