/*********************************************************************
*                                                               		*
*   Filename:      led_toggle.c													*
*   Date:          03/01/2013                                        *
*   Version:  		 1.0                                             	*
*   Author:        Goran Ljubic		                                 *
*                                                                    *
**********************************************************************
*                                                                    *
*   Architecture:  Microchip PIC Enhanced Mid-range Core             *
*   Processor:     16F1827                                           *
*   Compiler:      MPLAB XC8 v1.12 (Free mode)                       *
*                                                                    *
**********************************************************************
*                                                                    *
*   Description:    Primer 3				                              *
*                                                                    *
*  U primeru je obradeno citanje stanja tastera TA1 i prikazivanje   *
*  ovog stanja ukljucivanjem i iskljucivanjem LED1.                  *
*                                                                    *
*********************************************************************/


#include <xc.h>

#define _XTAL_FREQ  4000000     // frekvencija na kojoj radi interni oscilator. Neophodno definisati zbog delay() funkcija

/******************************************************************************************************************************
																																										*
CONFIGURATION WORDS																																				*
Watchdog timer is disabled, Internal RC oscillator I/O function on CLKIN pin, MCLR/VPP pin function is digital input, 			*
Program memory code protection is enabled, Brown-out Reset disabled, Power-up timer enabled, 											*
Data memory code protection is enabled, CLKOUT function is disabled. I/O or oscillator function on the CLKOUT pin,				*
Internal/External Switchover mode is disabled, Fail-Safe Clock Monitor is disabled, 														*
000h to FFFh flash memory write protected, 4x PLL disabled, Stack Overflow or Underflow will not cause a Reset,					*
High-voltage on MCLR/VPP must be used for programming																									*
																																										*
******************************************************************************************************************************/

   __CONFIG(WDTE_OFF & FOSC_INTOSC & MCLRE_OFF & CP_ON & BOREN_OFF & PWRTE_ON & CPD_ON & CLKOUTEN_OFF & IESO_OFF & FCMEN_OFF); 
   __CONFIG(WRT_ALL & PLLEN_OFF & STVREN_OFF & LVP_OFF); 


#define TA1_ON		RA4 == 0
#define TA1_OFF	RA4 == 1
#define LED1_ON	LATB0 = 1
#define LED1_OFF	LATB0 = 0

#define PRESSED	1
#define RELEASED	0


unsigned char dbc;

struct
{
	unsigned TA1_STATE:1;		// status bit tastera TA1 : 1 - PRESSED, 0 - RELEASED		
   unsigned TA2_STATE:1;		
   unsigned TA3_STATE:1;		
   unsigned TA4_STATE:1;		
   unsigned fill:4;
}CTRL;



/******************************
*	   	MAIN PROGRAM			*		
******************************/
void main(void)
{

/******************************
*		INITIALISATION				*
******************************/
	OSCCON = 0b01101010;		// 4x PLL is disabled, 4 MHz HF Internal oscillator block 

	ANSELA = 0; 				// Svi pinovi porta A onfigurisani kao digitalni I/O
	TRISA = 0b11111111;		// Svi pinovi porta A konfigurisani kao ulazni

	ANSELB = 0; 
	TRISB = 0b11111110;		// Pin RB0 konfigurisan kao izlazni
	LATB = 0b00000000;		// LED1 ugašena.

	dbc = 0xFF;

/******************************
*  		MAIN LOOP				*
******************************/

	while(1)
	{

		__delay_ms(1);          // Uzimanje uzorka obavlja se svake milisekunde

		dbc <<= 1;					// pri cemu se najpre pomocna promenljiva dbc pomera za jedno mesto ulevo.

		if(TA1_OFF)					// Ukoliko taster nije pritisnut na mesto bita najmanje težine upisuje se jedinica
			dbc |= 1;

		if(dbc == 0)				// Ako je dobijeni rezultat 0x00 znaci da smo za najmanje 8 ciklusa imali
		{								// stanje stabilne logicke nule
			CTRL.TA1_STATE = PRESSED;		// pa cemo kontrolni flag tastera TA1 postaviti u stanje PRESSED
			dbc = 0xFF;				// a kontrolnu promenljivu dbc postaviti ponovo na pocetnu vrednost.
      } 								// Ovime su prakticno postavljeni uslovi za novi ciklus ocitavanja stanja tastera.
		else if(dbc == 0xFF)		// Ukoliko je dobijeni rezultat 0xFF to znaci da smo imali stabilno stanje logicke jedinice
				CTRL.TA1_STATE = RELEASED;		// i da je taster otpušten pa je kontrolni flag postavljen u stanje REALASED

		if(CTRL.TA1_STATE == PRESSED)		// Ovaj deo koda se odnosi na vizuelno obeležavanje stanja tastera TA1 pa ukoliko je taster pritisnut
			LED1_ON;							// svetlece LED1
		else									// a ukoliko je otpušten
			LED1_OFF;						// LED1 ce biti iskljucena.

	}
}