3a

#include <xc.h>
#include<stdio.h>
#include<stdlib.h>
#include <time.h>
#define _XTAL_FREQ 1000000

#pragma config OSC = INTIO67    // Oscillator Selection bits (Internal oscillator block, port function on RA6 and RA7)
#pragma config FCMEN = OFF      // Fail-Safe Clock Monitor Enable bit (Fail-Safe Clock Monitor disabled)
#pragma config IESO = OFF       // Internal/External Oscillator Switchover bit (Oscillator Switchover mode disabled)

// CONFIG2L
#pragma config PWRT = OFF       // Power-up Timer Enable bit (PWRT disabled)
#pragma config BOREN = ON       // Brown-out Reset Enable bits (Brown-out Reset enabled and controlled by software (SBOREN is enabled))
#pragma config BORV = 3         // Brown Out Reset Voltage bits (Minimum setting)

// CONFIG2H
#pragma config WDT = OFF        // Watchdog Timer Enable bit (WDT disabled (control is placed on the SWDTEN bit))
#pragma config WDTPS = 32768    // Watchdog Timer Postscale Select bits (1:32768)

// CONFIG3H
#pragma config CCP2MX = PORTC   // CCP2 MUX bit (CCP2 input/output is multiplexed with RC1)
#pragma config PBADEN = OFF     // PORTB A/D Enable bit (PORTB<4:0> pins are configured as digital I/O on Reset)
#pragma config LPT1OSC = OFF    // Low-Power Timer1 Oscillator Enable bit (Timer1 configured for higher power operation)
#pragma config MCLRE = ON       // MCLR Pin Enable bit (MCLR pin enabled; RE3 input pin disabled)

// CONFIG4L
#pragma config STVREN = ON      // Stack Full/Underflow Reset Enable bit (Stack full/underflow will cause Reset)
#pragma config LVP = OFF        // Single-Supply ICSP Enable bit (Single-Supply ICSP disabled)
#pragma config XINST = OFF      // Extended Instruction Set Enable bit (Instruction set extension and Indexed Addressing mode disabled (Legacy mode))

// CONFIG5L
#pragma config CP0 = OFF        // Code Protection bit (Block 0 (000800-001FFFh) not code-protected)
#pragma config CP1 = OFF        // Code Protection bit (Block 1 (002000-003FFFh) not code-protected)
#pragma config CP2 = OFF        // Code Protection bit (Block 2 (004000-005FFFh) not code-protected)
#pragma config CP3 = OFF        // Code Protection bit (Block 3 (006000-007FFFh) not code-protected)

// CONFIG5H
#pragma config CPB = OFF        // Boot Block Code Protection bit (Boot block (000000-0007FFh) not code-protected)
#pragma config CPD = OFF        // Data EEPROM Code Protection bit (Data EEPROM not code-protected)

// CONFIG6L
#pragma config WRT0 = OFF       // Write Protection bit (Block 0 (000800-001FFFh) not write-protected)
#pragma config WRT1 = OFF       // Write Protection bit (Block 1 (002000-003FFFh) not write-protected)
#pragma config WRT2 = OFF       // Write Protection bit (Block 2 (004000-005FFFh) not write-protected)
#pragma config WRT3 = OFF       // Write Protection bit (Block 3 (006000-007FFFh) not write-protected)

// CONFIG6H
#pragma config WRTC = OFF       // Configuration Register Write Protection bit (Configuration registers (300000-3000FFh) not write-protected)
#pragma config WRTB = OFF       // Boot Block Write Protection bit (Boot block (000000-0007FFh) not write-protected)
#pragma config WRTD = OFF       // Data EEPROM Write Protection bit (Data EEPROM not write-protected)

// CONFIG7L
#pragma config EBTR0 = OFF      // Table Read Protection bit (Block 0 (000800-001FFFh) not protected from table reads executed in other blocks)
#pragma config EBTR1 = OFF      // Table Read Protection bit (Block 1 (002000-003FFFh) not protected from table reads executed in other blocks)
#pragma config EBTR2 = OFF      // Table Read Protection bit (Block 2 (004000-005FFFh) not protected from table reads executed in other blocks)
#pragma config EBTR3 = OFF      // Table Read Protection bit (Block 3 (006000-007FFFh) not protected from table reads executed in other blocks)

// CONFIG7H
#pragma config EBTRB = OFF      // Boot Block Table Read Protection bit (Boot block (000000-0007FFh) not protected from table reads executed in other blocks)


#pragma config OSC = INTIO67  //OSCILLATOR SELECTION BITS (INTERNAL OSCILLATOR BLOCK, PORT FUNCTION ON RA6 AND RA7)
#pragma config WDT = OFF      //Watchdog Timer Enable bit (WDT disabled (control is placed on the SWDTEN bit))
#pragma config PWRT = OFF     //Power-up Timer Enable bit (PWRT disabled)
#pragma config BOREN = ON     //Brown-out Reset Enable bits (Brown-out Reset enabled in hardware only (SBOREN is disabled))
#pragma config PBADEN = OFF   //PORTB A/D Enable bit (PORTB<4:0> pins are configured as digital I/O on Reset)
#pragma config LVP = OFF      //Single-Supply ICSP Enable bit (Single-Supply ICSP disabled)
#pragma config CPD = OFF      //Data EEPROM Code Protection bit (Data EEPROM not code-protected)

void __interrupt(high_priority)H_ISR(){
    
    //step4
    int value = (ADRESH<<2)|(ADRESL>>6) ;
    value = (int)(value/(1024/64));
    CCPR1L = value>>2;
    CCP1CONbits.DC1B = value%4;
    __delay_ms(1);
    //do things
    
    
    //clear flag bit
    PIR1bits.ADIF = 0;
    
    ADCON0bits.GO = 1;
    
    //step5 & go back step3
    /*
    delay at least 2tad
    ADCON0bits.GO = 1;
    */
    
    return;
}

void main(void) 
{
    //configure OSC and port
    OSCCONbits.IRCF = 0b100; //1MHz
    TRISAbits.RA0 = 1;       //analog input port
    
    //step1
    ADCON1bits.VCFG0 = 0;
    ADCON1bits.VCFG1 = 0;
    ADCON1bits.PCFG = 0b1110; //AN0 ?analog input,???? digital
    ADCON0bits.CHS = 0b0000;  //AN0 ?? analog input
    ADCON2bits.ADCS = 0b000;  //????000(1Mhz < 2.86Mhz)
    ADCON2bits.ACQT = 0b001;  //Tad = 2 us acquisition time?2Tad = 4 > 2.4
    ADCON0bits.ADON = 1; //enable A/D
    ADCON2bits.ADFM = 0;    //left justified 
    
    
    //step2
    PIE1bits.ADIE = 1; //enable A/D interrupt
    PIR1bits.ADIF = 0; //clear A/D interrupt bit
    INTCONbits.PEIE = 1; //enable peripheral interrupt
    INTCONbits.GIE = 1; //enable interrupt


    //step3
    ADCON0bits.GO = 1; //set go/done bit
    
    //init
    TRISC = 0;
    LATC = 0;
    T2CONbits.TMR2ON = 0b1;
    T2CONbits.T2CKPS = 0b01;

    // Internal Oscillator Frequency, Fosc = 125 kHz, Tosc = 8 ?s
    OSCCONbits.IRCF = 0b001;
    
    // PWM mode, P1A, P1C active-high; P1B, P1D active-high
    CCP1CONbits.CCP1M = 0b1100;
    
    // CCP1/RC2 -> Output
    TRISC = 0;
    LATC = 0;
    
    // Set up PR2, CCP to decide PWM period and Duty Cycle
    /** 
     * PWM period
     * = (PR2 + 1) * 4 * Tosc * (TMR2 prescaler)
     * = (0x9b + 1) * 4 * 8?s * 4
     * = 0.019968s ~= 20ms
     */
    PR2 = 0x9b;
    
    /**
     * Duty cycle
     * = (CCPR1L:CCP1CON<5:4>) * Tosc * (TMR2 prescaler)
     * = (0x0b*4 + 0b01) * 8?s * 4
     * = 0.00144s ~= 1450?s
     */
//    CCPR1L = 8;
//    CCP1CONbits.DC1B = 0;

    
    
    
    
    while(1);
    
    return;
}