#include <htc.h>
__CONFIG(INTIO & WDTDIS & PWRTDIS & MCLRDIS & UNPROTECT & BORDIS & IESODIS & FCMDIS);
#define bitset(var,bitno) ((var) |= 1 << (bitno))
#define bitclr(var,bitno) ((var) &= ~(1 << (bitno)))

void io_port_setup(void)
{
	// Sets all bits for port C for output
    TRISC = 0b00000000;

	// All bits for port C are off
    PORTC = 0b00000000;

	// Sets all bits for port A for input
	TRISA = 0b00111111;

	ADON = 1;

	// RA0/AN0 connected to the A/D
	ANSEL = 0b00000001;
	ANSELH = 0b00000000;

	// The result will be left aligned in ADRESH
	ADFM = 0;
	// We are using VCC as reference
	VCFG = 0;
	// We are sampling AN0
	ADCON0 = ((ADCON0 & 0b11000011) | 0b00000000);
	// Clock source is F/2
	ADCON1 = ((ADCON1 & 0b10001111) | 0b00000000);	

	// Clears A2D interrupt flag
	ADIF = 0;
	// Allows A2D to trigger an interrupt 
	ADIE = 1;
	// Allows for PE interupts
	PEIE = 1;
	// Start a conversion
	GODONE = 1;	
}

void PWM_setup(void)
{
	// Select PWM mode, P1D active high;
	CCP1CON = ((CCP1CON & 0b11110000) | 0b00001100);
	// Select Single output
	CCP1CON = ((CCP1CON & 0b00111111) | 0b00000000);
	// Steer the output to P1C or RC3
	STRC = 1;

	// No post-scaler
	T2CON = ((T2CON & 0b10000111) | 0b00000000);
	// 16 as a prescaler
	T2CON = ((T2CON & 0b11111100) | 0b00000011);
	// Frequency: 61 Hz
	PR2 = 0xFF;

	// Duty cycle: 0 (OFF)
	CCP1CON = ((CCP1CON & 0b11001111) | 0b00000000);
	CCPR1L = 0;	
	
	// Timer is ON!
	TMR2ON = 1;
}

static void interrupt interupt_handler(void)
{
	// Was the interrupt generated by A2D?
	if (ADIF == 1)
	{
		// Update the Duty Cycle
		CCPR1L = ADRESH;
		CCP1CON = ((CCP1CON & 0b11001111) | ((ADRESL & 0b11000000) >> 2));
		GODONE = 1;	
		ADIF = 0;
	}
}


void main( void)
{
	// set the oscillator speed to 1 MHz
	OSCCON = ((OSCCON & 0b10001111) | 0b01000000);

	// setup the ports
	io_port_setup();

	// setup PWM
	PWM_setup();

	// Interrupts are on
	GIE = 1;

	// Loop forever
	while (1)
	{
	}
}