#include <C8051F020.H>
#include <stdio.h>

/* Sine Wave Value Table */
unsigned char idata sintab [] = {
0x00, 0x01, 0x03, 0x04, 0x06, 0x07, 0x09, 0x0A, 
0x0C, 0x0E, 0x0F, 0x11, 0x12, 0x14, 0x15, 0x17, 
0x18, 0x1A, 0x1C, 0x1D, 0x1F, 0x20, 0x22, 0x23, 
0x25, 0x26, 0x28, 0x29, 0x2B, 0x2C, 0x2E, 0x2F, 
0x30, 0x32, 0x33, 0x35, 0x36, 0x38, 0x39, 0x3A, 
0x3C, 0x3D, 0x3F, 0x40, 0x41, 0x43, 0x44, 0x45, 
0x47, 0x48, 0x49, 0x4A, 0x4C, 0x4D, 0x4E, 0x4F, 
0x51, 0x52, 0x53, 0x54, 0x55, 0x57, 0x58, 0x59, 
0x5A, 0x5B, 0x5C, 0x5D, 0x5E, 0x5F, 0x60, 0x61, 
0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 
0x6A, 0x6B, 0x6C, 0x6C, 0x6D, 0x6E, 0x6F, 0x70, 
0x70, 0x71, 0x72, 0x73, 0x73, 0x74, 0x75, 0x75, 
0x76, 0x76, 0x77, 0x77, 0x78, 0x79, 0x79, 0x7A, 
0x7A, 0x7A, 0x7B, 0x7B, 0x7C, 0x7C, 0x7C, 0x7D, 
0x7D, 0x7D, 0x7E, 0x7E, 0x7E, 0x7E, 0x7F, 0x7F, 
0x7F, 0x7F, 0x7F, 0x7F, 0x7F, 0x7F, 0x7F, 0x7F };

static unsigned char DA_next_out;
static unsigned int i;

void timer0_isr (void) interrupt 1
{
/* Output D/A Value */
DAC0L = 0x00;
DAC0H = DA_next_out;

/* Calculate next D/A Value */

if (i++ >= 511) i = 0;

if (i >= 384)
  DA_next_out = 127 - sintab[127 - (i % 128)];  /* 180 - 270 quadrant */
else if (i >= 256)
  DA_next_out = 127 - sintab[i % 128];          /* 90 - 180 quadrant  */
else if (i >= 128)
  DA_next_out = 128 + sintab[127 - (i % 128)];  /* 0 - 90 quadrant    */
else
  DA_next_out = 128 + sintab[i];                /* 270 - 0 quadrant   */
}

void main ( void )  {

/*     Watchdog Timer Disable     */
EA = 0;
WDTCN= 0xDE;
WDTCN= 0xAD;
EA = 1;

/*	        Init DAC	            */

REF0CN = 0x03;            /*  Enable DAC Bias Generator, Internal Ref Buffer        */
DAC0CN = 0x87;	 					/*  Enable DAC 0, Update on Write to IDA0H, 2.0mA current	*/


/*	Initialize Timer 0 Interrupt	*/

TMOD  = 0x02;               /* TMOD: Timer 0, mode 2, 8-bit reload        */
TH0   = 240;                /* TH0:  Reload value                         */
TL0   = 251;                /* TL0:  Reload value                         */
ET0   = 1;                  /* ET0:  Enable timer 0                       */
TR0   = 1;                  /* TR0:  Timer 0 run                          */
EA    = 1;                  /* EA:   Enable interrupts                    */

while (1);
}