PS2IntDecoder.c

This program decodes the key strokes from a PS/2 keyboard, connected to a PS/2 click module. It echoes each pressed key to the UART          terminal and stores on a rx buffer. When the ENTER key is pressed, a line feed together with the content of the rx buffer are sent to the UART terminal, as a demonstration purpose.

It doesn´t sends commands to the keyboard; SHIFT, CAPS LOCK and ENTER keys are functional as expected when using a keyboard.

This program is based on the following:
Original title: keyboard_pc_to_rs232.c
Description: Interface between an AT keyboard and a RS232C port.
Date: Abr-2005. Author: XP8100 (xp8100@gmail.com)

Based on the AN AVR313: Interfacing the PC AT Keyboard from ATMEL.
Adapted for a 16F628A by Redraven. Link (in Spanish):
http://picmania.garcia-cuervo.net/proyectos_teclado_ps2.htm

Describes the functioning of the Ps/2 keyboard, codes, commands and connections. Also describes in detail the communication protocol and implements the code for a PIC 16f628.

Adapted for the MikroC compiler and PIC18F45K22 by AlexBG.

The array of n rows by 3 columns for the scan codes, comes from:
http://www.lucadavidian.com/2017/11/15/interfacing-ps2-keyboard-to-a-microcontroller/

The code for using two pointers to the buffer comes from:
https://libstock.mikroe.com/projects/view/641/serial-to-glcd-for-easypic7

Hardware and connections.
You can use the Mikroe PS/2 click (https://www.mikroe.com/ps2-click) or build your own based on the schematic for this module; but for this program, do not connect it into the mikro BUS. Use the connections described below.

PS/2 Module       EasyPIC 7
  CS (CLK)              RB0
RST (DATA)            RB3
     VCC                   +5V
     GND                  GND

The reason for these connections is because the sample code provided for the Mikroe PS/2 click module, does not makes use of the external interrupt INT, located at RB0.

This program does use the external interrupt INT, located at RB0. On each falling edge of the clock signal, an interrupt is generated and at     that moment, the level at RB3 pin is checked, for decoding the corresponding value (8 bits) for the pressed key.

EasyPIC V7 settings:
- Enable the USB UART terminal with J3 and J4.
- Select the ON position for SW1.1 and SW2.1.
- Connect your PS/2 click module to any of the external PORTB connectors.