scruss

The Quirkey: chording USB keyboard

This may not look much, but it’s a test build of Vik Olliver’s Quirkey USB chord keyboard. I didn’t quite build it to Vik’s specs, which are here:

The Microwriter was a late 1970s/early 1980s gadget that was essentially a portable word processor. Unusually, its keyboard was a single-hand 6 key layout — the thumb did double duty — that was operated by chording multiple keys at the same time. Later on in the Microwriter’s life it evolved into the Quinkey, a chording adaptive keyboard for computers of the time.

Technology has moved on a bit, and the ability to wire up a cheap USB-capable microcontroller and 3d print your own case is here. I used an Arduino Micro on a breadboard and six Omron momentary buttons.

I didn’t quite wire it the way that Vik intended:

Note lifted pins to prevent useless buttons

The buttons are wired like this:

Pin      Button
=======  =======
 D8       Control
 D7       Thumb
 D6       Index
 D5       Middle
 D4       Ring
 D3       Pinkie

This requires changing line 22 of Vik’s code from:

const int keyPorts[] = {8, 7, 6, 5, 4, 9};

const int keyPorts[] = {8, 3, 4, 5, 6, 7};

While there are great tutorials on “microwriting” in the original manuals on Bill Buxton’s site, here are the basic alphabetic set derived from Vik’s code:

Thumb
|Index
||Middle
|||Ring
||||Pinkie
●○○○○ : Space
○●○○○ : e
●●○○○ : i
○○●○○ : o
●○●○○ : c
○●●○○ : a
●●●○○ : d
○○○●○ : s
●○○●○ : k
○●○●○ : t
●●○●○ : r
○○●●○ : n
●○●●○ : y
○●●●○ : .
●●●●○ : f
○○○○● : u
●○○○● : h
○●○○● : v
●●○○● : l
○○●○● : q
●○●○● : z
○●●○● : -
●●●○● : '
○○○●● : g
●○○●● : j
○●○●● : ,
●●○●● : w
○○●●● : b
●○●●● : x
○●●●● : m
●●●●● : p

The astute reader may note that these are binary values (low bit to high) of the character positions in Vik’s alphaTable variable. And yes, that’s supposed to be preformatted text.

Happy microwriting!

Tact & Buttons

The right and wrong ways to connect buttons

Buttons, Tactile switches, Momentaries, Clickies, SPST-NO; call ’em what you will, but my world seems to be full of them right now. Wiring them or breadboarding them may not be as simple as they look.

Whether they are the tiny 6 mm ones of the less-easily-lost 12 mm ones, both types typically have four pins or legs, two on the top and two on the bottom. If your appear to have the legs on the sides, flip ’em 90°: they won’t fit in breadboard sockets the wrong way.

The pins on the left and right side are common, so connecting top left to bottom left won’t ever change state if you press the button. So use either the pins both on the same side or those diagonally opposed if you want the switch to work.

You can use these buttons on a common breadboard rail. You must remember to have only one button pin connecting to the rail; lift the other pin so it won’t connect. You can then use just one wire connected diagonally across the the common rail pin and you’ve got a working button. This is especially useful when using a microcontroller with built-in pull up resistors (that’s most of them these days).

If you connect both pins to a common rail, you’ve just made a SPST-AO (single pole, single throw – always open) switch. Those aren’t much use at all.