avr_ps2 - C library for PS2 input on AVR

PS2 keyboard clock and data wires should be connected to the uc.
Clock will trigger PCINT interrupts, and the library then reads pressed key from the data wire. ASCII code of the pressed key will be pushed in a buffer, that can be red from outside of interrupt vector.

avr_ps2 supports different keymaps, configured at compile time by including the corresponding keymap header file, for example for us keymap:
#include "ps2_keymap_en.h"

Pins and other settings can be configured in a conf.h file in your source files.
Default is PORTC, pin PC0 for PS2 clock and pin PC1 for PS2 data.

Tested on atmega328p.

See example.c for an example of use.


=== References ===

= Tuto
2011, Vladimir Milosavljevic http://www.electronics-base.com/projects/complete-projects/108-avr-ps2-keyboard-key-readout
http://extremeelectronics.co.in/avr-tutorials/ps2-keyboard-interface-with-avr-mcu/
http://playground.arduino.cc/Main/PS2Keyboard
http://retired.beyondlogic.org/keyboard/keybrd.htm
    assembly
https://www.avrfreaks.net/forum/ps2-lcd-interfacing
    interesting post from Simonetta

= Libs
https://github.com/PaulStoffregen/PS2Keyboard
http://www.technoblogy.com/list?1H0V
https://github.com/techpaul/PS2KeyAdvanced
Watch PS/2 keyboard signals to add extra keyboard noise with relays (AVR / Arduino)
        https://gist.github.com/stecman/89ba440e97c8bafe8d1bb0ebe02025dc
https://github.com/das-labor/legacy/tree/master/microcontroller/src-atmel/playground/gauselmann
        hard to use

= Usb - ps2 pinout
http://pinouts.ru/InputCables/usb_ps2_mouse_pinout.shtml
	Some USB keyboard firmwares support PS2 fallback, in use with a USB-PS2 adapter (usually passive, just wires)