DAC转换输出波形

使用DA转换输出正弦波，三角波，锯齿波

（1）仿真电路图

（2）源代码

absacc.h

‘‘absacc.h’’ 文件通常是keil C51编译器的一个头文件，用于访问特殊功能寄存器和实现对底层硬件的底层控制。这个头文件为底层寄存器提供了直接访问，允许程序员对特殊功能进行底层的控制。其中包含特殊的宏定义和内联汇编，用于直接操作芯片的寄存器。

#ifndef __ABSACC_H__
#define __ABSACC_H__

#define CBYTE ((unsigned char volatile code  *) 0)
#define DBYTE ((unsigned char volatile data  *) 0)
#if !defined (__CX2__)
#define PBYTE ((unsigned char volatile pdata *) 0)
#endif
#define XBYTE ((unsigned char volatile xdata *) 0)

#define CWORD ((unsigned int volatile code  *) 0)
#define DWORD ((unsigned int volatile data  *) 0)
#if !defined (__CX2__)
#define PWORD ((unsigned int volatile pdata *) 0)
#endif
#define XWORD ((unsigned int volatile xdata *) 0)


#if defined (__CX51__) || defined (__CX2__)
#define FVAR(object, addr)   (*((object volatile far *) (addr)))
#define FARRAY(object, base) ((object volatile far *) (base))
#define FCVAR(object, addr)   (*((object const far *) (addr)))
#define FCARRAY(object, base) ((object const far *) (base))
#else
#define FVAR(object, addr)    (*((object volatile far *) ((addr)+0x10000L)))
#define FCVAR(object, addr)   (*((object const far *) ((addr)+0x810000L)))
#define FARRAY(object, base)  ((object volatile far *) ((base)+0x10000L))
#define FCARRAY(object, base) ((object const far *) ((base)+0x810000L))
#endif

#if defined (__CX2__)
#define HBYTE ((unsigned char volatile huge *)  0)
#define HWORD ((unsigned int volatile huge *)  0)
#define HVAR(object, addr)   (*((object volatile huge *) (addr)))
#define HARRAY(object, base) ((object volatile huge *) (base))
#endif

#define CVAR(object, addr)   (*((object volatile code *) (addr)))
#define CARRAY(object, base) ((object volatile code *) (base))
#define DVAR(object, addr)   (*((object volatile data *) (addr)))
#define DARRAY(object, base) ((object volatile data *) (base))
#define XVAR(object, addr)   (*((object volatile xdata *) (addr)))
#define XARRAY(object, base) ((object volatile xdata *) (base))

#endif

math.h

#ifndef __MATH_H__
#define __MATH_H__

#if defined __CX2__ && (__CX2__ >= 558 || __CX2__ == 556 && __CX2_MINOR__ >= 207)
#ifndef HUGE_VAL
#define HUGE_VAL __inf__
#endif // HUGE_VAL

#ifndef NAN
#define NAN __nan__
#endif // NAN

#pragma SAVE
#pragma FUNCTIONS(STATIC)
/* intrinsic functions are reentrant, but need static attribute */
extern int    abs  (int   val);
#pragma RESTORE
#endif

#pragma SAVE
#pragma REGPARMS
#if !defined (__CX2__)
extern char  cabs  (char  val);
extern int    abs  (int   val);
extern long  labs  (long  val);
#endif

extern float fabs  (float val);
extern float sqrt  (float val);
extern float exp   (float val);
extern float log   (float val);
extern float log10 (float val);
extern float sin   (float val);
extern float cos   (float val);
extern float tan   (float val);
extern float asin  (float val);
extern float acos  (float val);
extern float atan  (float val);
extern float sinh  (float val);
extern float cosh  (float val);
extern float tanh  (float val);
extern float atan2 (float y, float x);

extern float ceil  (float val);
extern float floor (float val);
extern float modf  (float val, float *n);
extern float fmod  (float x, float y);
extern float pow   (float x, float y);

#if defined (__CX2__)
extern float frexp (float val, int *exp);
extern float ldexp (float val, int exp);
#endif

#pragma RESTORE

#endif

main.c

#include<reg51.h>	    
#include<absacc.h>
#include<math.h>

#define PI 3.1415926

sbit CS=P2^7;
sbit WR12=P3^6;

//正弦波函数
void sine_wave_da(void)
{
	unsigned int i;
	for(i=0;i<255;i++)
	{
		XBYTE[0x7fff] = 127+127*(sin(2*PI*i/127));
	}
}

//三角波函数
void triangular_wave_da(void)
{
	unsigned int i;
	for(i=0;i<255;i++)
		XBYTE[0x7fff] = i;
	for(i = 255;i > 0; i--)
		XBYTE[0x7fff] = i;
}

//锯齿波函数
void sawtooth_wave_da(void)
{
	unsigned int i;
	for(i=0;i<255;i++)
		XBYTE[0x7fff] = i;
}

void main()
{
	CS=0;
	WR12=0;
	
	while(1)
	{
		//输出正弦波
		sine_wave_da();  
		//输出三角波
		triangular_wave_da();
		//输出锯齿波
		sawtooth_wave_da();
	}
}

（3）实验结果

正弦波仿真结果

三角波仿真结果

锯齿波仿真结果