3KM

Three key Madness (3KM) is a short C code based on the Techkeys.us 3-key business card firmware for minimal keyboards.

main features

1. short/long press deffrentiation - two different macros per key per mode (see below)
2. two modes - holding all three keys will change modes - two entire sets of macros ("mode changed" will be printed to context)
3. mode LED support - connect LEDs from PD4 to ground and from PD5 to ground to see what mode you are in (you may then also want to disable the mode change print)

Configurimg with your macros

1. clone/download the code
2. in the file main_techkeys.c you'll find arrays of keys named keys1..keys3 - 1,2&3 is the index of the button (they are numberd left to right) and without any suffix it will denote what happens on a short press in the default mode. The _long suffix is used to mark the macro for long presses and _b marks that this macro belongs to the second mode.
3. the key consts are listed in the file usb_keyboard.h
4. to hold shift on a certian charecter (for capital letters, '~', ':', etc.) add KSHIFT as the key previus to the key you want capitalized - so K2 will produce '2', but KSHIFT, K2 will produce '@'

example

uint8_t keys3_b_long[] = {KC, KD, KSPACE, KSHIFT, KTILDE, KSLASH, KS, KR, KC}; will produce cd ~/src when holding the rightmost button in mode 2

Deploy The Firmware to the chip

1. Create a firmware using make

2. Put your keyboard into bootloader mode

3. Program your .hex file (replace device type as necessary, your file should be in the ./bin dir)

    sudo dfu-programmer atmega16u2 erase
    sleep 10
    sudo dfu-programmer atmega16u2 flash /path/to/firmware.hex
   

AVR-dude may also be used on Linux, as explained here.