#include <p18cxxx.h>
#include <delays.h>
#include <timers.h>   

#pragma config FOSC = HSPLL_HS
#pragma config WDT = OFF
#pragma config PLLDIV = 3
#pragma config CPUDIV = OSC1_PLL2
#pragma config USBDIV = 2
#pragma config FCMEN = OFF
#pragma config PWRT = ON
#pragma config BOR = OFF
#pragma config BORV = 2
#pragma config LVP = OFF
#pragma config VREGEN = ON
#pragma config MCLRE = OFF
#pragma config PBADEN = OFF

#define SF        100000     // Sampling Frequency
#define ACCU    65536   // Accumulator

const unsigned char sinewave[] = // sine wave 256 values
{
0x80,0x83,0x86,0x89,0x8c,0x8f,0x92,0x95,0x98,0x9c,0x9f,0xa2,0xa5,0xa8,0xab,0xae,
0xb0,0xb3,0xb6,0xb9,0xbc,0xbf,0xc1,0xc4,0xc7,0xc9,0xcc,0xce,0xd1,0xd3,0xd5,0xd8,
0xda,0xdc,0xde,0xe0,0xe2,0xe4,0xe6,0xe8,0xea,0xec,0xed,0xef,0xf0,0xf2,0xf3,0xf5,
0xf6,0xf7,0xf8,0xf9,0xfa,0xfb,0xfc,0xfc,0xfd,0xfe,0xfe,0xff,0xff,0xff,0xff,0xff,
0xff,0xff,0xff,0xff,0xff,0xff,0xfe,0xfe,0xfd,0xfc,0xfc,0xfb,0xfa,0xf9,0xf8,0xf7,
0xf6,0xf5,0xf3,0xf2,0xf0,0xef,0xed,0xec,0xea,0xe8,0xe6,0xe4,0xe2,0xe0,0xde,0xdc,
0xda,0xd8,0xd5,0xd3,0xd1,0xce,0xcc,0xc9,0xc7,0xc4,0xc1,0xbf,0xbc,0xb9,0xb6,0xb3,
0xb0,0xae,0xab,0xa8,0xa5,0xa2,0x9f,0x9c,0x98,0x95,0x92,0x8f,0x8c,0x89,0x86,0x83,
0x80,0x7c,0x79,0x76,0x73,0x70,0x6d,0x6a,0x67,0x63,0x60,0x5d,0x5a,0x57,0x54,0x51,
0x4f,0x4c,0x49,0x46,0x43,0x40,0x3e,0x3b,0x38,0x36,0x33,0x31,0x2e,0x2c,0x2a,0x27,
0x25,0x23,0x21,0x1f,0x1d,0x1b,0x19,0x17,0x15,0x13,0x12,0x10,0x0f,0x0d,0x0c,0x0a,
0x09,0x08,0x07,0x06,0x05,0x04,0x03,0x03,0x02,0x01,0x01,0x00,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x00,0x00,0x00,0x01,0x01,0x02,0x03,0x03,0x04,0x05,0x06,0x07,0x08,
0x09,0x0a,0x0c,0x0d,0x0f,0x10,0x12,0x13,0x15,0x17,0x19,0x1b,0x1d,0x1f,0x21,0x23,
0x25,0x27,0x2a,0x2c,0x2e,0x31,0x33,0x36,0x38,0x3b,0x3e,0x40,0x43,0x46,0x49,0x4c,
0x4f,0x51,0x54,0x57,0x5a,0x5d,0x60,0x63,0x67,0x6a,0x6d,0x70,0x73,0x76,0x79,0x7c,
};

unsigned int delta;
unsigned char pos;
unsigned int phe;

#pragma interrupt isr save = PROD

#pragma code isrcode = 0x000008
void isr_direct(void)
{ 
    _asm  
        goto isr  
    _endasm
}

#pragma code
void isr(void)
{
    PIR1bits.CCP1IF = 0;
    phe += delta;
    pos = phe >> 8;
    PORTB = sinewave[pos];
}

void main (void)
{
    unsigned long freq;

    TRISB = 0;
    TRISC = 0;
    LATB = 0x00;

    T1CON = 0b11000001;
    CCP1CON = 0b00001011;
    PIE1bits.CCP1IE = 1;

    CCPR1L = 0x77;        // 50khz=ef 80khz=95 100khz=77 160khz=4a 200khz=3b
    CCPR1H = 0x00;

    INTCONbits.PEIE = 1;
    INTCONbits.GIE = 1;

    freq = 20000;
    delta = freq * ACCU / SF;

    while(1) {
        Delay10KTCYx(100);
        LATC ^= 0xff;
    }
}