demos/STM32/RT-STM32F334-DISCOVERY

# Quantum Hand-Wiring Guide

Parts list:
* *x* keyswitches (MX, Matias, Gateron, etc)
* *x* diodes
* Keyboard plate (metal, plastic, cardboard, etc)
* Wire (strained for wiring to the Teensy, anything for the rows/columns)
* Soldering iron set at 600ºF or 315ºC (if temperature-controlled)
* Rosin-cored solder (leaded or lead-free)
* Adequate ventilation/a fan
* Tweezers (optional)
* Wire cutters/snippers

## How the Matrix Works (Why We Need Diodes)

The microcontroller (in this case, the Teensy 2.0) will be setup up via the firmware to send a logical 1 to the columns, one at a time, and read from the rows, all at once - this process is called matrix scanning. The matrix is a bunch of open switches that, by default, don't allow any current to pass through - the firmware will read this as no keys being pressed. As soon as you press one key down, the logical 1 that was coming from the column the keyswitch is attached to gets passed through the switch and to the corresponding row - check out the following 2x2 example:

        Column 0 being scanned     Column 1 being scanned
                  x                                   x
                 col0     col1              col0     col1
                  |        |                 |        |
        row0 ---(key0)---(key1)    row0 ---(key0)---(key1)
                  |        |                 |        |
        row1 ---(key2)---(key3)    row1 ---(key2)---(key3)

The `x` represents that the column/row associated has a value of 1, or is HIGH. Here, we see that no keys are being pressed, so no rows get an `x`. For one keyswitch, keep in mind that one side of the contacts is connected to its row, and the other, its column.

When we press `key0`, `col0` gets connected to `row0`, so the values that the firmware receives for that row is `0b01` (the `0b` here means that this is a bit value, meaning all of the following digits are bits - 0 or 1 - and represent the keys in that column). We'll use this notation to show when a keyswitch has been pressed, to show that the column and row are being connected:

        Column 0 being scanned     Column 1 being scanned
                  x                                   x
                 col0     col1              col0     col1
Mode	Name	Size
-rw-r--r--	.cproject	4797	log stats plain
-rw-r--r--	.project	1182	log stats plain
-rw-r--r--	Makefile	6148	log stats plain
-rw-r--r--	chconf.h	16842	log stats plain
d---------	debug	82	log stats plain
-rw-r--r--	halconf.h	12120	log stats plain
-rw-r--r--	main.c	2607	log stats plain
-rw-r--r--	mcuconf.h	7571	log stats plain
-rw-r--r--	readme.txt	1081	log stats plain