timer.c

来自「在ccs上使用定时器实现一个数字震荡器的代码.产生的是正弦波波形。」· C语言 代码 · 共 92 行

/* ============================================================================*/ 
/*          Copyright (C) 2004 YINXING TECHNOLOGY CO., LTD                     */ 
/*                          All Rights Reserved.                               */ 
/* ----------------------------------------------------------------------------*/ 
/* ============================================================================*/ 



#include "stdio.h"

#define IMR 0
#define ST0 6
#define ST1 7
#define TIM 0x24
#define PRD 0x25
#define TCR 0x26
#define PMST 29

extern int counter = 25;
extern int flagxf = 0;
int con_buf=0;
float buf[128];           /*  save out wave buffer !  */

float y0;
float y1=0.30901699;
float y2=0.58778525;     /*  y2= y1*A */
const float aa=1.90211304;
const float bb=-1.;

                        
main()
{
  const int flag = 1;
  int *dest;

  dest = (int *)IMR;
  *dest = 0;

  dest = (int *)PMST;
  *dest = 0x1020;		/*	interrupt vector at 0x1000 */
  
  dest = (int *)TCR;
  *dest = 0x0010;

  dest = (int *)PRD;
  *dest = 2499;

  dest = (int *)IMR;
  *dest = 0x0008;			/* enable timer0 TINT0  */ 

  dest = (int *)TCR;
  *dest = 0x0030;
  *dest = 0x0000;

  asm (" rsbx intm");

  while ( flag )
  {
    if ( flagxf	== 0 )
      {
	asm( " RSBX XF");
	asm( " nop" );
	asm( " nop" );
	asm( " nop" );
      }
    else 
      {
        asm(" SSBX XF");
	asm( " nop" );
	asm( " nop" );
	asm( " nop" );
      }

  }

}


void interrupt tint()
{   

	y0 = aa*y1 + bb*y2;
	y2 = y1;
	y1 = y0; 
	
	buf[con_buf]=y0;
	con_buf++;
	if(con_buf == 128)
	    con_buf=0;            /* set breakpoint to show wave ! */
	
}