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https://gitlab.com/evils/waad

Getting my feet wet on keyboards, een voor de hand liggend project.
https://gitlab.com/evils/waad

capacitive dvorak keyboard plover qwerty steno stenography touch

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Getting my feet wet on keyboards, een voor de hand liggend project.

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README 

        
= waad steno keyboard

Evils 

:homepage: https://gitlab.com/evils/waad

:license: CERN-OHL-W-2.0

:keywords: steno, stenography, capacitive, touch, keyboard, plover, dvorak, qwerty

:toc2:

:sectanchors:

:sectlinks:



== Requirements

=== Hardware

* split unit from one 100x100mm PCB

* capacitive touch keys

* at least 22 keys for steno

* micro sd card slot

* all solder joints reworkable with iron

* at least 1 RGB status LED



=== Software

* output over USB as a HID

* raw key press output option



== Problems

* a chord consists one or more keys, possibly pressed by the same finger

** includes pressing multiple keys in a column

*** and pressing 2-4 of the outer pads at once (`H-*`, `-TD`, maybe `-TSDZ`)

* a word, phrase or character is a value in a dictionary the key for which being a sequence (length 1 to at least 11) of chords

* there are implicit rules (in plover) for appending common suffixes (like 'ing' or 's' for pluralization) to dictionary entries

* keeping the dictionary on the chip is not practical, external RAM could work, but price (and loading time?) rule that out



== Approaches

=== Hardware

==== Mechanical

* 100x100mm PCB (plus some compensation for the milled slot if the manufacturer allows it)

* single sided load

** USB type C on the bottom of one (left?) half

*** requires feet high enough to clear the cable

*** rules out through hole mechanical pins?

** interconnect, capacitive sense chip(s) and (minimal) MCU on top on the other half

* homing

** notch at the edge between the thumb pads as a resting spot

*** leave complementary bump at pinky?

*** these may need a dead zone / cut corners, to allow resting

** crosses/blobs of silicone on the nodes may help to detect a near miss

*** if these are thick enough, and the signal of a normal touch large enough, they may be a dead zone and allow for resting and dead reckoning

**** cutting corners under these may help

*** `-TSDZ` may also be needed, prefer not to make that a dead zone / resting position



=== Electrical



=== Software

* expand dictionary to make suffix rules etc. explicit

* retrief dictionary entries at decode time from sd card



== Rev 0 goals

* try out an MCU with integrated cap touch sensing

* try out USB Type C

* try out microSD card

* try out a recent board/pad design

** try at least the "dumb" row split (straight line, no interdigitation)

*** maybe try out {tilde}3mm truncated zigzag interdigitation with minimal clearance (0.2mm?)

** feel the thumb notch on a 1.6mm board on rubber feet

* try 20% hatched and solid ground fill behind pads

* trial having the MCU under pads

* find out if routing sense traces under pads is a problem



== Wanted Features

=== Hardware

* all components on top of both halves, to lay flat

** not possible with skewed split from 1 PCB

*** 2x left from 1 PCB, 2x right from 1 PCB would work

**** may still lack board area

* fallback to microswitches, if pad design and sensing allow it



=== Software

* multiple optional filter definitions

. map from available hardware pads (board specific naming) to something standardized

*** 22-32 capacitive pads to 22 steno keys or to qwerty/dvorak/whatever

. map chords to words

*** steno decompression / lookup in an (expanded) dictionary

. map words to an output format

*** to allow dealing with host side remapping (dvorak on qwerty main keyboard)

* "paper" output (display at least the buffered chords)

** separate output, maybe an emulated serial port? (mirror on hardware?)

* dotterel style sticky keys to build up a chord

* keep steno and qwerty keyboard connected to a PC set to remap qwerty to dvorak and use either without reconfiguring the PC

* steno standard output like `Gemini PR` or `TX Bolt`

* near infinite undo

* usage statistics

** error statistics

** problem: passwords

* fallback to raw output when sd card is missing



=== Both

* use either side standalone

* break out pins for PS/2 touchpad/trackpoint and/or GPIO

* break out pins for a display for the "paper" output

* DIP switches / solder blob programming

** 2 bits to set e.g.: `qwerty / no / azerty / dvorak` HID output

*** to compensate for what the receiving device expects

** 2 bits to set `60% emulation / steno / raw / arbitrary` pad to keystroke mapping

** 1 bit power switch

** 1 bit for firmware flashing or recovery

** 1 user bit



== Speculation

* quick estimate, 1M entries per language, 500 bytes per entry, 4 languages (and assuming none of these have any chords in common) and a doubling in size after pre-digesting to apply `-ing`, `-s`, etc rules

** that's 4gb, 32gb microsd card is < €10

* longest combo in the plover supplied dictionary is 11 chords (allow for at least 20?)

* a chord is defined by the keys pressed within the span of the first key being pressed pressed and the last being released?

** finger repositioning should be possible, especially with capacitive sense

** keys that were pressed some time before all are released



== Notes

* IME (Input Method Editor) is a portable OS native path to implementing the translation



== Copyright and License

This work is: +

Copyright 2020, evils. +

Licensed under CERN-OHL-W v2 +

(SPDX identifier: {LICENSE}) +

Source Location: {homepage} +

(Please keep that link available if you modify this work.)



== Links

=== Hardware

* {homepage}

** this project, experimental unrealized hardware

* https://www.st.com/en/microcontrollers-microprocessors/stm32f072rb.html

** all the touch related Application Notes in the resources

* Microchip, Renesas, Cypress, Semtech all have touch related ANs, i may link some here if i read any and find them useful



=== Software

* https://github.com/crides/steno

** reuses some stuff from dotterel

** expands dictionary with rules, collapses it to a tree

** runs on a 32u4 with an sd card, bottlenecked on output to computer

** dedicated hardware included

* https://github.com/nimble0/dotterel

* https://github.com/mike-ady/Stenokey

* https://github.com/StarGazer1258/Charadriidae

** a steno engine written in C from scratch

* https://github.com/CharleyShattuck/myforth-arduino

* https://github.com/stanographer/plover-pi/blob/master/plover_raspbian.sh

* https://github.com/FromtonRouge/qmk_firmware/tree/master/users/fromtonrouge

** uses several regex rulesets

* https://www.mykeyboard.co.uk/keyswitches/